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The final stage of the Little Ice Age in Europe was characterised by strong climatic variability. New documentary sources containing information referring to weather and climate are used in this study to reconstruct and to describe climate conditions in Portugal during the 18th century, mainly in the 1780s. Indexation of documentary data concerning hydric and thermal conditions was based on C. Pfister's methodology and early instrumental data (1780s and 1790s) were used to verify the reconstruction. Precipitation and temperature were highly variable throughout the 18th century: an alternation of extremely hot to extremely cold months was found. Very cold years occurred mostly in the first 2 decades of the 18th century, but several other cold winters were also detected. Precipitation information is far more frequent than for temperature, and allowed yearly and seasonal indexations. The highest variability was de tected in the 1730s and the 1780s. The early 1780s were very dry: during the winter and spring of 1781 and the spring of 1782 several drought episodes occurred, as confirmed by 'pro-pluvia' rogations. In contrast, heavy precipitation prevailed from 1784 onwards. The year 1786 was the rainiest in Portugal, triggering floods in northwestern and central Portugal. The year of 1788 was extremely wet and rainfall caused floods along the largest rivers: Douro, Mondego and Tagus. A storm that struck North - western Iberia between 23 and 24 February 1788 is analysed in detail.
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Clim Res
Vol. 66: 141–159, 2015
doi: 10.3354/cr01337 Published online October 20
According to the IPCC fifth assessment report
(2013) and its ‘Special report on managing the
risks of extreme events and disasters to advance
climate adaptation’ (IPCC 2013), southern Europe
is a climate change hot spot (see also Giorgi 2006),
where the intensity and frequency of climatic
extremes are projected to increase over the next
decades (Kovats et al. 2014). Knowledge from past
climates can help understand climate variability
and change by weighting natural versus external
climatic forcing, thus improving fu ture projections.
Furthermore, the availability of longer climatic
series contributes to a greater understanding of
an thropogenic forcing, particularly at regional scales
(Zorita et al. 2010, Masson-Delmotte et al. 2013),
where additional processes may modulate climate
responses under external forcing (Gómez-Navarro
et al. 2014).
© Inter-Research 2015 ·*Corresponding author:
Climatic extremes in Portugal in the 1780s based
on documentary and instrumental records
Marcelo Fragoso1,*, David Marques1, João A. Santos2, Maria João Alcoforado1,
Inês Amorim3, João Carlos Garcia4, Luís Silva3, Maria de Fátima Nunes5
1Centre for Geographical Studies, Institute of Geography and Spatial Planning (IGOT-UL), Universidade de Lisboa, Lisboa,
2Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB,
Universidade de Trás-os-Montes e Alto Douro, (UTAD), Vila Real, Portugal
3Transdisciplinary Research Centre ‘Culture, Space and Memory’(CITCEM), Faculdade de Letras, Universidade do Porto,
4Centro Interuniversitário de História das Ciências e da Tecnologia (CIUHCT), Universidade de Lisboa, Lisboa, Portugal
5Universidade de Évora, (IHC-CEHFCi.UE), Évora, Portugal
ABSTRACT: The final stage of the Little Ice Age in Europe was characterised by strong climatic
variability. New documentary sources containing information referring to weather and climate are
used in this study to reconstruct and to describe climate conditions in Portugal during the 18th
century, mainly in the 1780s. Indexation of documentary data concerning hydric and thermal con-
ditions was based on C. Pfister’s methodology and early instrumental data (1780s and 1790s) were
used to verify the reconstruction. Precipitation and temperature were highly variable throughout
the 18th century: an alternation of extremely hot to extremely cold months was found. Very cold
years occurred mostly in the first 2 decades of the 18th century, but several other cold winters
were also detected. Precipitation information is far more frequent than for temperature, and
allowed yearly and seasonal indexations. The highest variability was de tected in the 1730s and
the 1780s. The early 1780s were very dry: during the winter and spring of 1781 and the spring of
1782 several drought episodes occurred, as confirmed by ‘pro-pluvia’ rogations. In contrast, heavy
precipitation prevailed from 1784 onwards. The year 1786 was the rainiest in Portugal, triggering
floods in northwestern and central Portugal. The year of 1788 was extremely wet and rainfall
caused floods along the largest rivers: Douro, Mondego and Tagus. A storm that struck North -
western Iberia between 23 and 24 February 1788 is analysed in detail.
KEY WORDS: Climate variability · Little Ice Age · Extreme events · Storm · Portugal
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Clim Res 66: 141–159, 2015
Previous climate studies of Europe (Alcoforado et
al. 2000, Barriendos & Llasat 2003, Diodato 2007,
Camuffo et al. 2010, 2013, Luterbacher et al. 2012)
have identified a lack of instrumental data in Iberia
during the Early Instrumental Period (EIP: 1780−
1830; Xoplaki et al. 2001) compared to other Euro-
pean regions (Brázdil et al. 2005, 2010a). Over the
last decades there has been a growing interest in his-
torical climatology in Iberia. Natural proxies, namely
tree-rings (Dorado-Liñán et al. 2015, Santos et al.
2015), documentary sources (Alcoforado et al. 2000,
Taborda et al. 2004, Domínguez-Castro et al. 2008,
2012, Rodrigo et al. 2012, Domínguez-Castro et al.
2014) and early instrumental data (Alcoforado et al.
2012, Domínguez-Castro et al. 2013, Fernández-
Fernández et al. 2014) are being used to reconstruct
past climate.
The final stage of the Little Ice Age (LIA) period
in Europe was characterised by strong climatic varia -
bility (Kington 1988, Pfister et al. 1998, Brázdil et al.
2010b), particularly in the western Mediterranean
basin between 1760 and 1800 (the ‘Maldá anomaly’;
Barriendos & Llasat 2003). In Iberia, this hydromete-
orological anomaly was characterised by a sequence
of either severe droughts or intense precipitation and
floods. Additionally, temperature extremes were also
identified, such as the severe cold winter of 1788−89
(Taborda et al. 2004). This strong variability was also
evident in Portugal, with severe dry years occurring
in 1779 and 1781 and a rainy period during 1783−
1789 (Taborda et al. 2004). Moreover, the Lakagígar
volcanic eruption, which started in June 1783 and
lasted until February 1784, also influenced weather
and climate worldwide (Highwood & Stevenson
2003, Thordarson & Self 2003, Trigo et al. 2010, Alco-
forado et al. 2012).
The vast majority of European countries were al -
ready carrying out meteorological observations in
the second half of the 18th century (Kington 1988,
Brázdil et al. 2005, 2010a). Portugal took part in this
progress, with instrumental measurements begin-
ning in the last quarter of the 18th century (Alco-
forado et al. 2012). These early meteorological ob -
servations allow for a characterisation of climatic
variability in Portugal, particularly in the 1780s,
which is the decade with the most valuable and reli-
able instrumental data of the 18th century. In addi-
tion to the availability of instrumental re cords, the
finding of relevant documentary sources and the
identification of the 1780s as a decade with numer-
ous climatic extremes in Portugal were further
important motivations to undertake the present
research. There remain important gaps in the un -
derstanding of climatic variability in Southwestern
Europe during the final stage of LIA. The present
study aims to address this knowledge gap, by ana -
lysing early meteorological observations and docu-
mentary sources. The 3 specific objectives of the
present study are:
(1) To use new documentary data from different
historical sources with climate-related evidence for
the 1700s in Portugal, covering several locations
(2) To carry out a climatic reconstruction and an
identification of extremes for the 1780s in Portugal,
based on documentary sources and early meteoro-
logical records
(3) To analyse and discuss the meteorological con-
ditions and impacts of a particularly violent storm in
northwestern Iberia (23−24 February 1788).
2.1. Documentary data
The present study is partly based on new descrip-
tive documentary sources, collected under the frame-
work of the KlimHist project (Alcoforado et al. 2015) .
This database as sembles hand-written and printed
information on weather and climate from 1645 to
1815 in Portugal. It allows for systematic queries of its
records, classified according to their level of reliabil-
ity, type of reported event, date and location. Fur-
thermore, metadata re ferring to sources (e.g. type of
source, archives, collections, library codes) and rele-
vant transcriptions are included. A synthetic presen-
tation of the historical sources (HS) used for the cli-
mate reconstruction in Portugal is depicted in in
the Appendix, where they are classified using an
adapted version of the Brázdil et al. (2010a) classifi-
cation. The number of available sources increases
markedly from the 17th to the 18th century. The doc-
umentary sources of the 18th century are briefly
described below and a summary of the sources con-
cerning the 1780s is shown in Table 1. The documen-
tary proxy data used consist mainly of individual and
institutional sources (Brázdil el al. 2010a).
Individual sources include memoirs, newspapers
and voyage books. Memoirs contain descriptions
of events directly or indirectly related to weather
and climate, (sometimes with comparisons with what
would be expected as ‘normal’ atmospheric condi-
tions); information is found in texts reporting wars,
diseases, mortality or revealing agricultural losses,
harvests dates or other phenological aspects of crops.
After the development and diffusion of handwritten
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Fragoso et al.: Extremes in 18th century Portugal
and printed press in the 17th century in Portugal,
several newspapers divulge information on weather
and climate, particularly citing extreme events and
associated impacts on health and agriculture. The
dissemination of quantitative meteorological data in
printed newspapers only started in the 19th century,
with the publication of the Franzini meteorological
observations (Alcoforado et al. 2015). Voyage books
of foreigners visiting Portugal provide useful infor-
mation through their descriptions of meteorologi -
cal conditions and their comparison with weather
and climate in their countries of origin. International
interest in Portugal increased after the 1755 Lisbon
earthquake, and subsequent writings of philosophers
such as Voltaire.
Institutional sources include records maintained
by hospitals, bishoprics, municipalities and military
au thorities. These documents were created to com-
pile a record of activities and notable facts and/or to
permit later inquiries or audits. This led to a certain
level of organisation of the records and, conse-
quently, these sources offer more reliable and
homogenous information compared to individual
sources. Ecclesiastical and civil documentary sources
provide the most useful proxy data. Numerous
minutes of the cathedrals and official letters of pre -
lates contain information on anomalous weather
and climate conditions and news on processions and
‘pro-pluvia’ and ‘pro-serenitate’ ceremonies (to ask
God for rain, or to stop the rain, respectively) (Alco-
forado et al. 2000, Barriendos & Llasat 2003, Bar-
riendos & Rodrigo 2006). Regarding civil sources,
the minutes of town-halls also give indirect infor -
mation on weather extremes, since municipalities
occasionally had to limit water consumption (e.g. in
case of drought events), or had to support public
works to reconstruct damaged infra structure (e.g.
due to floods and storms), or needed to react to
price rises due to poor harvests caused by adverse
meteorological/climatic episodes.
Document type Title/description (source) 1780 1785 1790
Individual Sources
Memoirs Memórias (HS3)
Várias notícias de casos (HS18)
Lembranças (HS17)
Descrição topográfica … (HS35)
Poem Mondegueida Poema… (HS37)
Voyage books Três Diários de Viagem em Portugal (HS38)
Viagem a Portugal (HS44)
Viagens a Portugal (HS38)
Private Correspondence Letter by João Pereira (HS10)
Newspapers Gazeta de Lisboa/ Supl. (HS25−33)
O Tripeiro (HS20, HS36)
O Conimbricense (HS24)
Curiosidades de Guimarães (HS21)
Almanach de Lisboa (HS40−42)
Institutional Sources
Civil Livro dos Termos (HS4)
Actas da Vereação (HS5)
Memoria sobre os dannos do Mondego… (HS22)
Livro das Cartas de D. José I (HS2)
Ecclesiastical Assentos do Cabido (HS7−9)
Livro das Procissões (HS1)
Cartas do Cabido da Sé (HS6)
Early meteorological data J.Veiga (HS14)
J. Pretorius (HS12, HS40−43)
J. Velho (HS15−16, HS45−48)
H. Schulze (HS13)
Table 1. Main documentary and early instrumental sources used for climate reconstruction in mainland Portugal. References
in brackets are to historical sources (HS) listed in the Appendix. Orange: documentary sources available; red: annual data;
yellow: monthly data; green: daily data; grey: data presumed to exist, but not found
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Clim Res 66: 141–159, 2015
In order to evaluate the quality of the compiled
information and the reliability of the descriptions,
a cross-comparison of sources was carried out;
biographical examinations (e.g. instruction level
and scientific skills) of every individual record
were useful to estimate the relevance of the de -
scriptions. Furthermore, each report introduced
in the database was classified according to its
reliability, from Level 1 (low quality) to Level 3
(high quality), in order to select the most accurate
and useful proxy data, based on a quality control
of all gathered documentary information.’
2.2. Instrumental data
As instrumental data are already described in
detail by Taborda et al. (2004) and Alcoforado et
al. (2012), only a brief summary is given here (cf.
Table 2). The earliest records began in 1770 in
Lamego in northern Portugal (Fig. 1) and were
carried out by J. B. Veiga. During the 1780s, J. A.
Velho, J. C. Pretorius and H. Schulze conducted
meteorological observations in the Lisbon region.
Velho made 3 daily weather observations in
Mafra, 30 km northwest of Lisbon, from 1783 until
1787. Detailed metadata are provided (Table 2).
Data from Pretorius’ station in Southwestern Lis-
bon are available from 1781 to 1785 and for 1793
(although others must have existed), whereas
data measured by Schulze are only available for
1789. Velho and Pretorius described in detail
their instruments and, along with Veiga, were
also members of the Lisbon Royal Academy of
Sciences. Parts of their data were published by
this institution.
2.3. Methods
2.3.1. Documentary data retrieval and
The KlimHist database currently contains 3045
entries extracted from 263 different sources. The
most reliable qualitative data were transformed
into semi-quantitative information, commonly
known as climatic indices, expressed at monthly
or seasonal scales. Following Taborda et al. (2004,
p. 16), it should be stated that the documentary
records ‘were based on extreme situations with
socio-economic impact, the indices are inter-
preted as a measurement for the behaviour of
(Real Colégio de Mafra) (Real palácio de Nossa (Alcântara)
Senhora das Necessidades)
Weather observer João Borges Joaquim da Jacob Chryso- Henrique Schulze
da Veiga Assunção Velho stomo Pretorius
Location of observations
Latitude N ? 38° 57’ 20’’ 38° 42’ 23’’ (?) ?
Longitude W ? 8° 47’ 30 9° 10’17’’ (?) ?
Altitude ? 500−600 ft (162−194 m) 45−50 m (?) 6 fathoms (13.2 m)
above sea level
Observation period(s) 1770−1784 1783−1787 1777, 1781−1785,1793 1794 1789
Temporal resolution Annual 3 daily observations Monthly Monthly
Observed parameters / Units of Measurement
Atmospheric pressure French system French system French system French system
Temperature °F °F °F °F
Precipitation French system French system French system French system
Wind direction √√ √ √
Wind velocity x 5 grades from 1 (no/adj.) to Handspan s−1, foot s−1, Fathom s−1
5 (very strong stormy wind) inch s−1, fathom s−1
Humidity x x 24 level scale 24 level scale (?)
Cloudiness 3 grades Various adjectives 3 grades 3 grades
Severe weather events Snow, thunderstorm, storm, etc. Thunderstorm, storm, etc.
Table 2. General description of the instrumental data collected for the 18th century in Portugal (adapted from Taborda et al. 2004). Ticks: available data; crosses: unavailable
data; question marks: unknown or not confirmed information. no/adj.: no wind/undetectable
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Fragoso et al.: Extremes in 18th century Portugal
extreme phenomena (intense and prolonged rainfall
or droughts), rather than for the average precipita-
tion’. Therefore, the methodology proposed by Pfis-
ter (1992) and also applied by other authors (Alco-
forado et al. 2000, Rodrigo & Barriendos 2008) was
used to reconstruct hydric conditions in the 1700s. A
monthly Precipitation Index (PI) for Portugal was
obtained through the quantification of descriptive
documentation. The value −1 corresponds to a ‘dry’
month and +1 to a ‘wet’ month; 0 values represent
either ‘normal’ (average) months or those with un -
clear information. As recommended by previous
studies (Alcoforado et al. 2000, Rodrigo & Barriendos
2008), summers (June−August) were excluded from
the analysis, as summertime precipitation in Portugal
is typically very low. Winter is defined as Decem-
ber−February, spring as March−May and autumn as
September−November. Seasonal and annual indices
were then obtained through algebraic sums of monthly
indices. Thus, seasonal indices vary between −3 and
+3 and annual indices between −9 and +9. Overlap-
ping short periods between documentary and instru-
mental data allowed for the verification of the climate
reconstruction. The scarcity of documentary evidence
for temperature throughout the 1700s, however, does
not allow for its indexation. Nevertheless, a recon-
struction methodology using the same principles as
used for hydric indexation was applied to tempera-
ture variability in the 1780s, taking advantage of the
higher amount of retrieved documentary evidence
for this period.
2.3.2. Early instrumental data
Besides documentary descriptions, the other main
source of information used in this research is early
instrumental data. Monthly temperature and precip-
itation series from the 3 available observation sites
were used to characterise the 1780s. Given the differ-
ent locations and measurement conditions of these
early observations, their climatic meaningfulness must
Fig. 1. Location of the meteorological stations in the 1780s (a) in Portugal and at (b) Lamego, (c) Mafra and (d) Lisbon in rela-
tion to the hypsometry of the area. ( , ) Meteorological station in the 1780s, with name of the observer; ( ) location of
the nearest modern meteorological station for each site, indicating the period of observations
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Clim Res 66: 141–159, 2015
be carefully interpreted. Hence, the analysis should
preferably be based on anomalies (differences to
local average values). These anomalies may be
expressed in standard deviation units from long-term
means (e.g. the 1901−1960 baseline; Brázdil et al.
2005). However, due to the absence of long climatic
series, it was only possible to compute these anom-
alies by comparison with the nearest modern stations
(Alcântara/Lisboa, Mafra and Lamego; Fig. 1b−d, re -
spectively). The closest stations with available cli-
matic normals were then chosen as a baseline (Lis-
boa/Geofísico, Mafra-Tapada and Peso da Régua,
Figs. 1b−d, respectively). The 30 yr period 1931−1960
was chosen as a baseline, being the only period
with climatic normals available for the 3 selected ref-
erence stations. The sensitivity of the precipitation
index to the chosen baseline period cannot thereby
be tested due to the lack of data. Furthermore, these
normals are only for precipitation, since Mafra-
Tapada and Peso da Régua are rain gauge stations.
These restrictions lead to another method for the esti-
mation of anomalies. They were obtained by dividing
monthly, seasonal and annual rainfall totals, re -
corded in each station during the 1780s, by the corre-
sponding mean amounts (1931−60 normal) of the
reference station. Positive anomalies are therefore
expressed by non-dimensional values: >1 for wet,
1 for near-average and <1 for dry conditions.
As stated above, the available temperature obser-
vations for the 1780s did not permit an estimation of
anomalies. The Mafra temperature series (the single
location with daily records and restricted to 1783−
1787 period; Table 2) was used to evaluate the fre-
quency of cold and hot days, at seasonal scale, by
selecting, respectively, days with minimum (maxi-
mum) temperature below (above) 6°C (25°C). These
limits chosen correspond to temperature thresholds
identified by prior regional climatic studies of the
Mafra region (Daveau 1985).
According to documentary sources, the first 2
decades of the 18th century were particularly cold.
‘Between 1720 and 1790, not only did the references
to ‘cold’ diminish, they were also confined to winter
and spring’ (Taborda et al. 2004, p. 16). Several hot
months were detected, related to a positive North
Atlantic Oscillation index (NAO index). In additon,
very cold winters also took place in 1708−09,
1739−40 and 1788−89; they also occurred in several
parts of Europe and were related to negative NAO
index. Available information does not yet permit the
construction of a detailed graph for temperature
during the 18th century (like that shown in Fig. 3d
for precipitation).
The 18th century was characterised by a high pre-
cipitation variability in Portugal (Fig. 2d), particularly
in the first 2 decades, in the 1730s and in the 1780s.
Extensive rains persisted from 1706 until 1709, fol-
lowed by very dry years, particularly from 1712 to
1716. During 1730s, very dry periods (1734, 1737
and 1738, during which pro-pluvia ceremonies took
place) alternated with prolonged rainy periods (1732
and 1736, when pro-serenitate ceremonies are regis-
tered) (Taborda et al. 2004). However, the highest
variability occurred in the 1780s, with very dry years
until 1782, followed by heavy and persistent rainy
seasons until the end of the 1780s (Fig. 2c). This
decade was chosen for a detailed study in this paper
due to its high climatic variability, but also because
early instrumental sources were available (Alco-
forado et al. 2012), permitting validation of informa-
tion extracted from documentary sources and com-
parison of precipitation and temperature values with
present ones. In Fig. 2a the occurrence of successive
hydroclimatic extremes in the 1780s can be ob served.
During the 18th century, based on documentary evi-
dence, only the decade 1700−1709 exhibits a compa-
rable frequency of positive rainfall anomalies (though
with less pronounced extremes). Among the impres-
sive number of extreme climatic events that occurred
in Portugal during the 1780s, we have selected the
violent storm of 23−24 February 1788 as a case study.
3.1. Temperature variability
Fig. 3 summarises temperature variability in Portu-
gal in the 1780s. According to early instrumental data
from Mafra (Fig. 3a), 1784 recorded the lowest mean
annual temperature (13.1°C), while 1785 and 1786
were the warmest years, with annual mean air tem-
perature of 14.7 and 14.8°C, respectively. The mean
annual air temperature in Mafra for 1783−1787 was
14°C. Negative anomalies in air temperature are com-
mon in Iberia during major winter droughts. In fact,
based on documentary sources (Fig. 3b) and some
meteorological observations carried out by Pretorius
in Lisbon (Fig. 3a), the beginning of the decade was
marked by cold and dry winters, particularly in 1782
and 1784. On 13 January 1782, Pretorius re corded 0°C
in Lisbon. The cold spell lasted several days and was
associated with unsettled weather, resulting in a
snowfall event on 19 February in Lisbon. The snow
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Fragoso et al.: Extremes in 18th century Portugal
reached a thickness of 11 cm and remained on the
ground for 2 days’ (HS27). Negative air temperatures
were recorded in December 1784. In addition, Preto-
rius (HS42) states that ‘the coldest weather conditions
(in Lisbon) were felt in the morning of the 4th with
−1.1°C and ice was also formed’, whilst daily mean air
temperature was 4.4°C in Mafra. This station shows
other low daily temperatures(1783− 1787), namely 2.2°C
on 4 January 1786 and 2.8°C on 4 April 1785.
In Portugal, the coldest winter of the decade oc-
curred in 1789 (strongest negative winter anomaly
visible in Fig. 3), with a cold spell in January. The
Fig. 2. Seasonal precipitation reconstruction in Portugal in the 1700s — (a,b) instrumental data; (c,d) documentary information.
(a,b) Rainfall anomalies (positive if value > 1, negative if value < 1) in (a) Mafra and (b) Lisbon. (c,d) precipitation indices in (c)
the 1780s and (d) the 18th century. In all panels, seasonal data are represented by bars and annual data by diamonds. Dot-dash
lines and the dashed line in (c) represent pro-pluvia and pro-serenitate rogation ceremonies, respectively. Shadowed areas in
(a) and (b) indicate gaps in instrumental data
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Clim Res 66: 141–159, 2015
mean monthly temperature for January in Lisbon was
9.9°C (HS13), 2.3°C lower than values collected by
Pretorius in 1784 and 1785 (HS11, HS12). The 1981−
2010 baseline January mean monthly temperature for
the Lisbon/Geofísico meteorological station is 11.6°C.
The maximum intensity of the cold wave reached
−1.7°C in Lisbon on 8 January (HS13), a value that is
lower than the extreme minimum air temperature
recorded in the Lisbon/Geofísico from 1854 until 2014
(−1.5°C). There are also references to very cold and
frosty weather conditions in Coimbra in 1789, with
several reported incidences of damage to crops, and
strong frosts and snowfall on 8−9 January in Chaves
and on 10 January in Oporto (HS33 N°4) (Fig. 1).
Some heat waves were also identified. The August
1784 heat wave was probably one of the most
severe of the 18th century in southern Portugal. Ac -
cording to Pretorius, temperatures reached 41.1°C
on 13 Au gust. This is only slightly lower than the
41.5°C maximum temperature recorded during the
June 1981 heat wave in Lisbon/Geofísico (despite
different kinds of metadata). In Mafra, the highest
record for this day was 33.9°C (HS16), a lower value
owing to its proximity to the Atlantic Ocean. Al -
though lower than the temperature in Lisbon, this
record corresponds to the hottest day in the period
1783−1787. Very high air temperatures also charac-
terised the summer of 1780 (the strongest positive
Fig. 3. Seasonal temperature reconstruction in Portugal in the 1780s. (a) Seasonal frequency of cold and hot days and seasonal
temperature extremes in Mafra. Shadowed areas indicate gaps in instrumental data. (b) Temperature index based on docu-
mentary data. Seasonal values have an all-inclusive range of +3 to −3, and annual values from + 9 to −9 (see Section 2.3.1 for
further explanation)
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Fragoso et al.: Extremes in 18th century Portugal
anomaly in Fig. 3). The scarcity of daily data does
not allow for an accurate assessment of length of the
heat wave. Still, it is possible to identify 2 maxima.
On 24 June at 12:00 h the air temperature was 37°C
and, on the following day, it rose to 40°C. In early
July 1784, the air temperature remained high. On 6
July the maximum temperature was 38.1°C, decreas-
ing to 28.9°C 2 d later.
3.2. Precipitation variability
The anomalous number of strong precipitation
extremes in the 1780s within the context of rainfall
variability in Portugal in the 18th century is clearly
suggested by Fig. 2d.
The evolution of the seasonal precipitation index
during the 1780s is depicted in Fig. 2b. The index
shows prevalent dry conditions until 1782, contrast-
ing with the wetter conditions during the remainder
of the decade. In fact, documentary evidence report-
ing dry conditions during the spring of 1780 was
found, with pro-pluvia rogations being held in
Oporto and Guimarães and decisions of tax credits
(‘quitas’) to farmers in Évora due to the ‘sterility’ of
the year. The following winter and spring of 1781,
and even the spring of 1782, were also characterized
by drought episodes. The rainfall deficits were
roughly estimated using the meteorological data of
Pretorius (only annual totals). In his published mete-
orological summaries, Pretorius stated that (HS40)
from the beginning of the year to 23 March, it hardly
rained (...) motivating our Eminent Prelate to order
public rogations in the churches of this capital’. The
year of 1782, particularly in spring, was the last of the
decade for which we have found documentary evi-
dence for drought, though it is less abundant.
The year of 1783 exhibits (Fig. 2) a transitional
character between the prevalent dryness of the early
years of the decade to the very rainy conditions that
prevailed thereafter. Data from Mafra and Lisbon
reveal no significant anomaly. Nevertheless, there is
documentary evidence suggesting that this year, at
least during the spring, was wet in Northern Portu-
gal, with the occurrence of a flood event in the Douro
River (Oporto) on 9−10 March (HS17).
As shown in Fig. 2, 1784 marked the beginning of a
sequence of very rainy years in Portugal, evident
both in the interannual variability of the precipitation
indices (seasonal to annual scales) and in the avail-
able early instrumental information (weighted total
amounts). The winter was rainy in Mafra and Lisbon,
while spring was even wetter (Fig. 2), triggering
floods and inundations in several regions, such as the
flood along the Douro River in March that was
reported by a contemporary witness (HS17). The
documentary evidence also shows that other cities
were severely affected by abundant rainfall during
the same month, particularly Lisbon and Braga,
where pro-serenitate public rogations were held on
the 16 and 30 of March 1784, respectively. We have
found less documentary information for 1785, though
it was a wet year according to Mafra and Lisbon data
(particularly the 1784−85 winter).
The year of 1786 may have been the rainiest of
this decade in Portugal (Fig. 2). In Mafra, the
annual precipitation was 1429.7 mm, whereas the
average amount in Mafra-Tapada in the period
1931−60 was of only 797.6 mm. In Lisbon, the total
amount was 1082.8 mm, which also represents a
strong deviation from the climate-mean amount of
the corresponding reference station (707.5 mm).
The long-lasting rainfall spells during winter and
spring triggered numerous floods across the coun-
try, some of them with high-impact consequences
in important cities like Braga, Oporto, Coimbra and
Lisbon. From 1 January to 31 May, Mafra records
show 30 d with precipitation above 10 mm, illus-
trating the high frequency of heavy rainfall days.
Throughout these months, numerous accounts of
floods along major Portuguese rivers can be found,
except for February 1786. The manuscript of
Henckel (HS17) reports 5 floods in the Douro River,
with peaks occurring on 14 January, 7 and 18
March, 10 April and 10 May. By 11 May 1786, the
excessive rainfall led the authorities of Braga to
proclaim 3 days of pro-serenitate rogations. In Cen-
tral Portugal, the severest flood occurred towards
the end of May, when 7 people were drowned by
the Mondego River waters (HS30 No. 24). Extensive
damage in the farmlands of the lower Mondego
valley was mentioned by the same source. Further
south, Lisbon was also affected by floods in
January and March (with rogation ceremonies held
on 24 March) (HS30 Supl. Nº12). The end of the
year, particularly November 1786, was again char-
acterised by heavy precipitation.
The following years were also rainy, although a
slight decrease in the seasonal and annual amounts
is suggested by the available sources (Fig. 2). The
documentary evidence referring to 1787 contains 3
descriptions of the impacts of severe thunderstorm
episodes, which in some cases triggered flash-floods.
Among these events, the thunderstorms of 22 May
(that caused severe agricultural damage in Torres
Novas, central Portugal) and 21 August (in Barcelos-
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Clim Res 66: 141–159, 2015
Braga, where several people were killed by lightning
strikes) stand out as the severest hazards. The year
1788 was again wet and there were floods along the
largest rivers: Douro, Mondego and Tagus. The par-
ticular relevance of a storm that occurred in February
1788 is detailed in Section 3.3.
The year 1789 was also rainy in Portugal (Fig. 2).
According to Schulze’s data, the rainiest seasons in
Lisbon were winter and autumn (HS13). The avail-
able documentary data clearly agree on the effects
of abundant rainfall throughout the year, except in
summer. Floods and inundations started early in
the year and occurred in Lisbon on 9 January
(HS33 Supl. Nº2) and in Oporto a few days later,
on 13−14 January (HS17). Several cities were af -
fected by floods later on, namely Coimbra (27 Jan-
uary; first week of May) and Ferreira do Zêzere (9
3.3. The February 1788 violent storm
There are significant gaps in information about
past extreme meteorological events in Portugal,
including those occurring during the 18th century.
Even so, the winter-storm ‘Barbara’ (3−6 December
1739) was a remarkable episode, with disastrous
impacts across mainland Portugal (Taborda 2006,
Pfister et al. 2010). For a better understanding of
storm events and their societal impacts in Portugal
during the Enlightenment period, an extreme storm
that struck northwestern Iberia between 23 and 24
February 1788 is analysed here in greater detail. This
extreme event was selected as a case study because
its impacts were very widespread and costly; in fact it
may have played a key role in the launching of the
national programme of public works during the gov-
ernment of Queen Mary I, as suggested by Martins
Fig. 4. (a) Principal disaster phenomena across Portugal and Spain triggered by the 23−24 February storm in 1788, and prob-
able limits of flooded areas in (b) Oporto (Portugal; according to HS3) and (c) Valladolid (Spain; according to HS38 and HS39)
Author copy
Fragoso et al.: Extremes in 18th century Portugal
(2014). This storm, and the subsequent flooding of
downtown Coimbra, inspired a poet (Francisco Mal-
hão) who witnessed the event, to write and publish a
long and impressive poem (‘Mondegueida’, HS37) on
the destructive effects of the flood. In spite of the
absence of instrumental data to support this case
study analysis, there is significant amount of newly
found documentary evidence reporting the conse-
quences of this high-impact storm, and this moti-
vated its reconstruction. The following description
follows the chronology of these accounts. This
enables a hypothetical reconstruction of the storm
trajectory and evolution, based on facts and details
from sources that are located in time. A summary of
the documentary evidence is presented in Table S2
in the Supplement at articles/
From a dynamical viewpoint, this violent storm
was presumably linked to an intense extratropical
cyclone. Such cyclones typically originate over the
North Atlantic and travel towards Europe. According
to Pinto et al. (2009), the large-scale conditions trig-
gering their development include anomalously strong
baroclinic zones associated with intense jet streams
over vast longitudinal sectors. These cyclones gener-
ate strong winds and extreme precipitation, being
a common feature of mid-latitude winter climates
(Fink et al. 2012).
There is evidence suggesting that the arrival of
this extratropical cyclone onto the Atlantic margin of
Iberia occurred on 19 February 1788, based on ac-
counts mentioning effects consistent with storm surge
conditions. On the night of 19 February 3 shipwrecks
near Caminha (on the northernmost coast of Portugal)
caused an unspecified number of victims. Further-
more, several ships lost their anchorage due to strong
winds in the Lisbon harbour (HS32 Supl. Nº13). The
following day (20 February 1788) was extremely
rainy. From 23 to 24 February the disastrous effects of
the intense rainfall and violent winds are described in
different locations. The reported impacts reveal a
temporal sequence and spatial incidence (Fig. 4) that
clearly suggest a westerly travelling system. The
storm started by crossing over northwest Portugal, af-
fecting Oporto and lower Douro basin, Alcobaça,
Coimbra and the Mondego valley. Shortly afterwards,
it moved on to Spain, passing over Salamanca,
Zamora, Valladolid (the Douro valley in Castilla-León
region), the Cantabrian coast and Navarra. Based on
the deduced storm track, the following analysis of the
impacts refer to 4 of the most affected areas.
(1) Floods and wind damage in the lower Douro
valley (Oporto, Northern Portugal). Between 20 and
22 February, the Oporto area was hit by strong west-
erly winds. Their force and frequency produced
damaging effects, such as uprooted and fallen trees
and the destruction of numerous roofs and skylights
(HS35). Meanwhile, the intensity of the rainfall dur-
ing the same 3 d period was responsible for a steady
rise in water levels of the Douro River in the Oporto
area (HS17, HS35). A newspaper (HS32 Nº11)
reported that between 24 and 25 February, in the
Oporto area, ‘the Douro River rose 31 hand spans
(6.89 m) above its ordinary level’, causing a ‘horrible
flood’. These reports are confirmed by the contempo-
rary descriptions by the wine merchant Henckel,
who stated that ‘we have recorded that in the greater
floods, the river rises up to 22 geometric feet (6.7 m),
measured from the point of the last low tide. The
river rose to nearly such heights during this last for-
midable flood, which occurred on the month of Feb-
ruary of this year of 1788’ (HS35). According to the
same source, the highest level of the flooding in
Oporto occurred during the night of 24 to 25 Febru-
ary when the water ‘rose above the street [alfândega]
and covered the square [terreiro]’. Henckel also
stated that by the afternoon of 25 February, the flood
level started to decrease, a steady trend observed
over the following days. The impacts of this storm on
the Oporto area were ‘very large’ (HS35) and the
periodical Gazeta de Lisboa reported an estimation
of total ‘costs of more than 2 million cruzados to
repair the damages in the city’ (HS32 N°14). A total of
18 streets and over 1000 dwellings were flooded in
downtown Oporto (HS35). Four wine warehouses
were demolished and a others suffered major dam-
age. Descriptions also report that several Oporto
streets (Cais da Ribeira, Rua da Porta Nova, Passeio
de Miragaia) were covered with sand (HS35) and 2
people were drowned in the Douro River.
(2) Floods in the Mondego valley (Coimbra) and
Alcobaça, Central Portugal. The impacts of the storm
were very severe in Coimbra, the largest city of Cen-
tral Portugal, located on the right bank of the Mon-
dego River. The rainfall was so intense during 23−24
February that it caused a huge flood (HS24, HS32
Supl. No. 11; HS37), the ‘largest flood within living
memory’ (HS32 Supl. No. 10). Several streets were
flooded in the downtown area, where ‘the waters
rose up to the Church of Santa Cruz’ (HS32 Supl.
No. 10; Fig. 5). As a result of this flood, the Coimbra
Bridge (built in 1513) was partially destroyed), and
several dwellings and mills were also damaged,
causing death (also in cattle) by drowning in the
Mondego River (HS32, Suppl. 10). Fig. 5 shows a
reconstruction of the destruction caused and proba-
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Clim Res 66: 141–159, 2015
ble flooding limits The exact number of human
deaths is not specified in this written source. In
Alcobaça, 85 km south of Coimbra, the storm caused
flash floods in 2 small catchments (Alcôa and Baça
rivers) (HS11, HS32 Supl. No. 10). Alcobaça is a city
well known for its Cistercian monastery, built in the
12th and 13th centuries. A fully detailed description
of the flooding by an eye witness, Manuel de Fi gu -
eiredo (HS11), vicar and chronicler, states that floods
of the Baça River, on the night of 23−24 February,
caused severe erosion of the riverbanks and the
destruction of several dwellings. On the same night,
the Alcôa River also rose rapidly and inundated
the terrains inside the monastery, causing panic to
the inhabitants. Although this episode did not
cause human casualties, the damage produced by
the flooding of the riverine areas of Alcobaça was
remarkable. Several dwellings were flooded and
walls, bridges and roads were destroyed (HS11).
(3) Flood and wind damage in the Douro valley in
the Castilla-León region of northern Spain. Be tween
24 and 25 February, as the storm moved eastwards,
the impacts of rainfall and wind gusts widened to
northern Spain. The storm triggered floods in the
Douro River in the plateau region of Castilla-León,
affecting the areas of Tordesillas and Valladolid
(HS19). The town of Tudela del Duero suffered major
impacts from flooding on the night of 24 February,
with damage to more than 100 dwellings, of which 30
were totally destroyed. The bridge of Boecillo, a vil-
lage near Tudela del Duero, was also destroyed and
the Monastery of El Abrojo suffered severe damage.
The most noteworthy impacts of this storm were
caused by the floods affecting the city of Valladolid,
located at the confluence of the Pisuerga and Es -
gueva rivers, tributaries of the Douro River. At the
time Valladolid was traversed by 2 branches of the
Esgueva, the main branch passing through the cen-
Fig. 5. Flood in Mondego valley, Coimbra, 24 February 1788 (reconstruction based on HS5, HS13 and HS37). The blue area
shows the probable limits of the flood. The Mondego River covered the Coimbra Bridge, destroying 3 arches (1), flooding the
downtown area of the city, where the waters reached the Santa Cruz Church (2) and damaging several buildings (3). This re-
constitution is overlaid on an engraving of Pieter van den Berg, titled Conimbrica, Lusitaniae urbs ad Mundam, aquaeductu
Sebastiani regis celebres, ca. 1720 (available at, based on Georg Hoefnagel’s drawing
(1566/67) published by Braun in Civitates Orbis Terrarum (Vol. 5, c.1598)
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Fragoso et al.: Extremes in 18th century Portugal
tral area of the city. The floods of 24−25 February
flooded the city centre, destroying or damaging more
than 150 dwellings. Twelve of the 14 bridges of Val-
ladolid were destroyed (HS34, HS49). The severity of
the flood damages was so pronounced that a fully
detailed survey (HS34) of the impacts was conducted
by the local authorities (Chancillería). An appeal was
made to the King to support the reconstruction, the
cost of which was estimated at over 470 000 Reales.
As a consequence of the storm, 6 days of pro-sereni-
tate rogations were ordered in Valladolid (HS49).
(4) Coastal storms on the Cantabrian coast, north-
ern Spain. The same memoir of Valladolid inunda-
tions (HS34) reports contemporary testimonials de -
scribing how the sea tides on 23−24 February ‘were
so high, rapid and impetuous, that the sea reached
distant places’ (HS34).
(5) Floods in Navarra, northern Spain. In Sierra de
Alcarama, the heavy precipitation on 24 February
caused flash floods in 2 river catchments (Añamaza
and Alhama rivers), in the upstream sector of the
Ebro basin (HS32 Supl. Nº13). Once again the ac -
counts make reference to the severity of the storm,
mentioning an ‘impetuous wind, a hurricane that
came from the west (...) and copious rainfall causing
a rise of Añamaza and Alhama rivers that had never
been seen before, leading to a violent deluge that
changed the devastated land’ (HS32 Supl. Nº13).
The geographic extension of the storm’s impacts
is considered to have been properly assessed by
the data presented to this point. Although a search
of documentary and instrumental records was car-
ried out for the same dates, by Mariano Barriendos
in Barcelona, Bilbao, Madrid, Murcia, Santiago de
Compostela, Seville, Toledo and Zamora, and by José
Vaquero in Zafra, no additional evidence of impacts
was found. Thus, we are confident that the storm
only affected northwest and northern Iberia.
Fig. 6. Monthly precipitation totals (contours in mm, with 20 mm interval) for (a) December 1787, and (b) January, (c) February
and (d) March 1788. Corresponding anomalies (colour shading) with respect to their long-term monthly means (baseline of
1773−1803, 31 yr period centred on 1788) are also displayed. Circles indicate gridboxes with statistically significant anomalies
at 95% confidence level. Data Source: Casty et al. (2007)
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Clim Res 66: 141–159, 2015
The consistency between the above-described
documentary sources and the information regarding
large-scale atmospheric flow obtained from an inde-
pendent dataset of atmospheric variables is now ana-
lysed. In order to identify anomalies in the large-
scale atmospheric flow during the 1787−88 winter,
the patterns of monthly precipitation totals and mean
500 hPa geopotential height are analysed for the
December−March period. These variables were ex -
tracted from reconstructions by Casty et al. (2007).
The gridded precipitation and geopotential fields
are defined over a North Atlantic/European sector
(80−30° N, 50° W−40°E) on 0.5° × 0.5° and 2.5° × 2.5°
grids, respectively. For precipitation, only the Iberian
Peninsula is represented. Monthly anomalies in the
2 previous fields were also computed with respect to
their cor responding long-term monthly means over a
31 yr baseline period centred on 1788 (1773−1803).
The statistical significance of the anomalies was also
as sessed by the Student’s t-test at 5% significance
The large-scale fields generally support the docu-
mentary sources, hinting at very high precipitation
values in February 1788, particularly over northwest-
ern Iberia where the storm first impacted the penin-
sula (Fig. 6) with local maxima >340 mm in Galicia,
northwestern Spain. The precipitation anomalies are
>120 mm over a large area extending from central
Portugal to Galicia. However, anomalously high pre-
cipitation totals are depicted over the entire Iberian
Peninsula, which are also statistically significant at
95% confidence level. Furthermore, the monthly
500 hPa geopotential height values clearly reflect the
key role played by large-scale patterns over the east-
ern North Atlantic on precipitation in western Iberia.
The anomalously weak anticyclonic ridge located
westwards of Iberia in February 1788 was accompa-
nied by a largely zonal flow (Fig. 7; note the statis -
tically significant negative anomalies over western
Europe, with a core anomaly <100 geopotential
metres). These conditions clearly suggest the pres-
ence of very strong cyclonic systems over western
Fig. 7. Monthly mean 500 hPa geopotential height (contours in metres) for (a) December 1787, and (b) January, (c) February
and (d) March 1788. Corresponding anomalies (colour shading) with respect to their long-term monthly means (baseline of
1773−1803, 31 yr period centred on 1788) are also displayed. Circles indicate gridboxes with statistically significant anomalies
at 95% confidence level. Data Source: Casty et al. (2007)
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Fragoso et al.: Extremes in 18th century Portugal
Europe that are favour able to the occurrence of pre-
cipitation in Portugal, associated with the passage of
frontal systems.
For the other months, however, there are no statis-
tically significant anomalies in precipitation (Fig. 6),
which reinforces the exceptionality of the conditions
in February 1788. Despite the much less pronounced
features, similar conditions as those in February 1788
can be observed in December 1787 (Fig. 7). Con-
versely, in January 1788, a very strong ridge can be
seen over the North Atlantic, consistent with the
relatively low precipitation values. Lastly, in March
1788, there is still a very strong mean trough in the
500 hPa geopotential height, though eastwardly
displaced with respect to the mean trough in the pre-
vious month. In fact, this result suggests a westerly-
moving trough, which is also in line with the findings
from the documentary sources. As the prevailing
wind over Portugal gradually changed from south-
west to northwest, the rain-generating conditions pro -
gressively weakened, also explaining the decreasing
precipitation anomalies.
The results show a remarkably high frequency and
strength of climatic extremes in the 1780s in Portu-
gal. This is in agreement with Kington’s statement:
‘The 1780s contain a number of outstanding temper-
ature and rainfall extremes, both positive and nega-
tive, which must represent some very pronounced
regional anomalies in the general circulation.’ (King-
ton 1988, p. 2; also cited in Barriendos & Llasat 2003).
According to the chronological sequence of extremes,
considering thermal and hydrometeorological events
separately, the main outcomes of the present study are:
(1) Detection of severely cold seasons in 1782 (win-
ter), 1784 (winter and spring) and 1789 (winter). The
occurrence of snowfall is extremely rare in Lisbon (on
average 0.0 d yr−1 in the 1961−1990 climatic normal),
but 1 event was documented in February 1782. The
winter of 1784 was also very cold in Portugal and
it was widely reported across Europe: in England
(where according to Kington 1980 the Thames River
froze in February), Belgium (Demarée 2006) and cen-
tral Europe (Brázdil et al. 2010b, Glaser et al. 2010).
This cold anomaly might have been driven by the
Lakagígar volcanic eruption. This eruption (occur-
ring from June 1783 until February 1784) was one of
the largest over the last 500 yr (Bradley & Jones 1995,
Trigo et al. 2010). Foggy and hazy days in the 1783
summer and lower than average air temperatures in
1784 were its main consequences in Portugal
(Taborda et al. 2004, Alcoforado et al. 2012). The
1789 winter was also characterised by an intense cold
wave in Portugal (maximum on 8 January), accord-
ing to the available instrumental and documentary
information. Over most of Europe the 1788/89 winter
was also exceptionally cold, with strong and persist-
ent frosts, snowfall in unusual areas and frozen rivers
(Le Roy Ladurie 1983, Barriendos 1997, Xoplaki et al.
2001). According to Barriendos (1997), 2 severe cold
epi sodes were observed in Iberia (26−31 December
1788 and 5−8 January 1789).
(2) Identification of the predominantly dry period of
1779−1782. During this period, 2 particularly severe
droughts were detected in Portugal, namely in the
spring of 1780 and in the winter and spring of 1781.
Due to its Mediterranean-like climate, droughts in
Portugal are mostly related to rainfall deficits dur-
ing the cold semester (October−March). Its dynami-
cal causes are commonly linked to strong and persist-
ent mid-latitude anticyclonic ridges over the eastern
North Atlantic (e.g. Santos et al. 2009). The 1780 and
1781 droughts were indeed a manifestation of large-
scale precipitation anomalies. They were also iden -
tified in Extremadura (Fernández-Fernández et al.
2014), Andalusia (Rodrigo et al. 2012) and central
Spain (Domínguez-Castro et al. 2012). The latter
includes specific references to pro-pluvia rogation
ceremonies, celebrated in the winter, spring and
autumn of 1781 in Seville, Murcia, Zaragoza and
(3) Details of the remarkable rainy period 1783−1789.
Ta borda et al. (2004) and Alcoforado et al. (2012) pre-
viously highlighted this very rainy period in southern
Portugal. The present study demonstrates that wet
conditions also prevailed over northern Portugal. For
7 consecutive years the estimated precipitation index
(PI) was strongly positive, values that are corrobo-
rated by the available instrumental data. At the
annual scale, the highest magnitude of these anom-
alies occurred in 1783/84, 1785/86 (+ 7/9) and 1787/
88 (+5/9). There is also a good agreement between
the detected precipitation extremes and results re -
ported by recent studies in Spain. In Anda lusia (a
region contiguous with Southern Portugal), Rodrigo
et al. (2012) identifies positive precipitation anom-
alies in 1784 and 1786, referring to the occurrence of
pro-serenitate ceremonies in Seville in both years.
Barriendos & Rodrigo (2006, their Fig. 5) also state
that a total of 7 floods in Seville (Guadalquivir River)
occurred during the 1780s. Five of them occurred in
winter and the remaining 2 in spring, though they do
not specify the years of those extreme events. Among
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Clim Res 66: 141–159, 2015
the mentioned rainfall (positive) ano malies, the 1783/
84 hydrological year featured ex ceptionally severe
climatic conditions, with catastrophic and wide-
spread impacts throughout Europe. Brázdil et al.
(2010b) state that the 1783/84 winter was character-
ized by low temperatures, heavy and persistent
frosts, icebound watercourses and high rates of snow
accumulation across extensive regions northwards of
the Alps. These conditions were followed by the most
hazardous floods recorded over the past millennium
in western-central Europe (Glaser & Stangl 2004,
Demarée 2006, Brázdil et al. 2010b). Most of these
floods were triggered by fast snowmelt and ice
breaking-up on frozen rivers (Brázdil& Llasat 2003,
Demarée 2006), thus being driven by different mech-
anisms from those occurring in 1784 over western
Iberia. According to several recent studies (Andrade
et al. 2011, Fragoso et al. 2012), positive anomalies of
winter precipitation in Portugal tend to be generated
by anomalously high frequencies of synoptic distur-
bances over the eastern North Atlantic, which are
also related to the NAO and East Atlantic patterns
(Gomes 2011, Trigo 2011).
(4) Details of the violent storm of February 1788.
The present study provided a more detailed analysis
of a severe Atlantic storm that crossed the northwest-
ern sector of Iberia, producing devastating floods in
the Douro River basin. This extreme event illustrates
the rainy conditions over 1783−1789, but is also evo -
cative of the high impacts of floods and correlated
vulnerabilities in the affected riverside urban centres,
particularly Valladolid (Spain) and Oporto (Portugal).
The present study suggests that strong climatic
variability was experienced in Portugal during the
1780s. Furthermore, it also shows that the excep-
tional atmospheric conditions during this decade over
Portugal are in clear agreement with the results
found by different authors over Spain, as well as over
other European regions. These results are also of rel-
evance for assessing the exceptionality of current or
future climate extremes in Portugal, as they provide
a comparative measure of the magnitude of a given
extreme. Future research will focus on the search for
additional documentary sources in other parts of the
country, improving the current KlimHist database
and providing further insight into the mechanisms
underlying climate variability in Portugal.
Acknowledgements. This study was carried out within the
framework of the KlimHist project ‘Reconstruction and
model simulations of past climate in Portugal, using docu-
mentary and early instrumental sources’ and was supported
by national funds from the Portuguese Foundation for Sci-
ence and Technology (Grant no. PTDC/AAC−CLI/119078/
2010). The authors are very grateful to Mariano Barriendos
and José Vaquero, who provided valuable information on
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Author copy
... Several previous studies have focused on the global climate reconstructions over the past few centuries to millennia Jones & Mann, 2004;Klus et al., 2018;Lamb, 1965Lamb, , 1995Luterbacher et al., 1999Luterbacher et al., , 2001Luterbacher et al., , 2006Mann, 2002;Mann et al., 1999Mann et al., , 2009Maslin et al., 2001;Santos et al., 2015). Evidence of anomalous weather and climate conditions (heavy rainfalls and droughts) appears in many ecclesiastic sources, often recorded as rogation ceremonies, used as documentary proxies to identify wet and dry A h e a d o f P r i n t 28 extremes in many parts of the world (Alcoforado et al. 2000;Bravo-Paredes et al., 2020;Domínguez-Castro et al., 2008, 2011, 2012Fragoso et al., 2015). The past climate reconstruction, based on both documentary sources and natural proxies' indicators, such as tree rings, ice cores, ocean, and coastal sediments, speleothems, corals, and borehole data (Clarke & Rendell, 2006;Jones & Mann, 2004;Luterbacher et al., 2006;Taborda et al., 2004), indicates several abrupt cold events in Europe, characterized by substantial surface cooling, freshening, and severe ice shift advance. ...
... This suggests, that in North and Western Europe, similar trends would be expected, consistent to NAO-mode ( fig. 2). In the Portuguese case, many studies have shown the influence of the NAO on precipitation regime, with rainy periods and storms compatible with NAO-phase, while dryness reflects prolonged NAO+ mode (Fragoso et al., 2015;Luterbacher et al., 2006). According to annual NAOi reconstruction in winter based on Trouet et al. (2009a), the beginning of the 16 th century is consistent with NAO-mode, which shifts to a prolonged NAO+ phase until the 1550s ( fig. 3). ...
... The beginning of the 18 th century exhibits strong climate variability with two first decades particularly cold Tudor, M., Ramos-Pereira, A., Gaspar de Freitas, J. Finisterra, LVI(118), 2021, pp. 25-50 A h e a d o f P r i n t 41 (Fragoso et al., 2015), followed by three rainy years between 1706-1709, and severe droughts in winter of 1711/12 and between the spring of 1714 and autumn of 1715 (Luterbacher et al., 2006). The temporal correspondence of the 1715 drought event and climate seem to be consistent with the end of the MM period and the transition to the subsequent global climate warming (Easterbrook, 2016). ...
Full-text available
The building of dunes and sand drifts along the European coastline are generally related to climatic variability and sea-level fluctuation. The last phase of dunes formation in south-western Europe coincides with the Little Ice Age (LIA) period characterized by pronounced climate variability. Historical sources retrieved from archives also report sand-drift events along the Portuguese coast. The sand invaded many agricultural fields, and settlements, forcing the inhabitants to move elsewhere. The article explores the temporal relationships between sand drift occurrences and climate, as a principal trigger for coastal dune migration. We used historical sources about sand-drift events as documentary proxies to infer the past climate variability on the Portuguese coast. Three spatial scales of climate variability were considered: i) the global climatic variability induced by the cold abrupt events over the last Millennium (LIA); ii) the regional (mesoscale) climate variability (NAO index), and iii) the local climate variability (extreme meteorological events). The paleoclimatic interpretation indicates that drifts in Portugal are related to both NAO modes, providing new insights into coastal dunes dynamics, as a response to natural drivers. However, the analysis of human activity on the coast also allowed us to better understand the relation of the local populations with their environments, highlighting those anthropogenic actions caused an additional disturbance on coastal dune dynamics.
... The manuscript is now lost, but it had fortunately been known to Vasco Valente, former director of Porto's Soares dos Reis Fine Arts Museum (Valente 1962). This Memoirs "Lembranças" de Inácio Henckell (Valente, 1962) ✓ source has been used by several authors (Tato 1966;Fragoso et al. 2015;Amorim et al. 2017;Silva 2019), but the present systematic analysis has revealed precious information about the Douro floods. Henckell (1712-1802) was born in Porto. ...
... At the end of the studied period, there are fewer accounts of floods, but the one in 1798 was considered "catastrophic". Indeed, Alcoforado et al. (2012) and Fragoso et al. (2015), based on the early Portuguese instrumental data, pointed out that the period between 1783 and 1789 was extremely rainy in Portugal. Reliable instrumental data from Porto, carried out by the physician JB Lopes, unfortunately only refer to 1792 and do not contain precipitation data (Alcoforado et al. 2012). ...
... Then the water level lowered so slowly that at the beginning of March it had not yet reached its normal level (Valente 1962). Similar situations occurred in other places in Portugal (Fragoso et al. 2015). There was a lot of damages to buildings, stores, roads and the 114 boats and vessels anchored in the Douro: "81 Portuguese, 28 British and 1 French, among others" (Costa 1789). ...
Full-text available
Extreme meteorological events have had devastating consequences all over the world throughout the ages. In this study, we look into the floods at the mouth of the Douro River (Porto, Portugal) in the eighteenth century to expand the data series of floods in Northern Portugal. Information was gathered mostly from documentary narrative sources, either individual or institutional (administrative and ecclesiastic), some of which include reports of Pro Serenitate ceremonies. A study by the priest Rebelo Costa (1789) and the memories of the merchant Ignacio Henckell from 1717 to 1800 stand out among the individual sources. We concluded that there was great interannual variability in the occurrence of the 54 recorded floods, the highest number of which occurred in the 1780s. The “catastrophic” floods were recorded in 1727, 1739, 1769, 1774, 1777, 1788 and 1798, four of which are studied in detail in this paper. The greatest number of flood events took place in winter and autumn, and most of them lasted between 1 and 3 days. An analysis of the description of the floods, their impacts and the associated meteorological causes was carried out. In most cases, the frontal activity associated with Atlantic cyclonic systems was the cause of positive precipitation anomalies in NW Iberia. The great variability in heavy precipitation was confirmed by the new data. However, hardly any temporal simultaneity was found with other case studies in Southern Europe, except for Spain, especially several localities of Galicia and the mid Douro Valley (Zamora).
... In this work we present a set of observations taken by the same observer in Granada (in the south of the country) some years before, between December 1728 and February 1730. These observations are included in a handwritten book dated to 1732 and kept in the Archive of the Franciscan Order in Cataluña (Gil Albarracín, 1997). The title of the book is Cielo y suelo granadino ('Sky and soil in Granada'; Fig. 1), and it may be regarded as one of the first Spanish medical treatises that followed the neo-Hippocratic hypothesis concerning the influence of climate on human health. ...
... The manuscript is dated to 1732, and although it was not ultimately published, the book was finished and prepared for publication. It is kept in the Library and Archive of the Franciscan Province of Cataluña, Barcelona, and it has been edited recently (Gil Albarracín, 1997). Among the multiple aspects of natural history studied by the author, we are interested in the climatological and meteorological observations. ...
Full-text available
The climatic information recorded by the physician Francisco Fernández Navarrete in Granada (southern Spain) during the first third of the 18th century is analyzed in this work. His observations are included in the book Cielo y suelo granadino ('Sky and soil in Granada'), and consist of qualitative comments relating climatic conditions to illness and diseases from 1706 to 1730, as well as instrumental observations (using an “English barometer” and a “Florentine thermometer”) from December 1728 to February 1730. To the best of our knowledge, these are the earliest instrumental observations recorded in Spain. An alternative methodology to Pfister indices, based on the frequency of extreme events, was applied to study this new set of documentary data. The analysis shows that seasonal mean values of temperature and precipitation during the period 1706–1730 were very similar to those of periods of similar length at the beginning of the 20th century, such as 1906–1930. However, some years were especially extreme, such as the dry first half of the 1720s or the winter of 1728–1729 when a strong cold wave affected the city.
... Las rogativas son una de las fuentes más utilizadas para la reconstrucción del clima histórico. De entre las investigaciones que, con diferentes orientaciones, han analizado el clima del pasado en el sur de la Península Ibérica podemos destacar en el sur de Portugal (Do Ó et al., 2008;Fragoso et al., 2015), sur de Extremadura y Andalucía (Barriendos, 2007;Rodrigo, 2007;2020;Rodrigo et al., 1999;2012;Fernández-Fernández et al., 2014). ...
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Copyright de los autores de cada artículo. Se permite su reproducción y difusión por cualquier medio, siempre que se haga sin interés económico y respetando su integridad Aportación de los "traslados" de la Virgen del Rocío al conocimiento del clima histórico (siglos XVII-XIX) en el SO de la península Ibérica Resumen Una forma particular de rogativa ante la adversidad meteorológica, en el suroeste español, es el traslado de la imagen de la Virgen del Rocío desde su ermita, en el interior de Doñana, hasta la villa de Almonte. Las ceremonias de traslados por sequía están documentadas en las actas capitulares de Almonte desde 1607, aunque no cuantifican la intensidad de cada episodio. Se utilizan cronologías regionales para elaborar índices ordinales comparados de severidad de los sucesos anuales registrados. Por frecuencia e intensidad destaca la incidencia de sequía anual durante los dos últimos tercios del siglo XVIII. Los resultados obtenidos mediante la información de los traslados de la Virgen, contribuyen al conocimiento del clima histórico en el área suroccidental de la península Ibérica. Palabras clave: Rogativas, sequía, Virgen del Rocío, clima histórico, Doñana. Abstract A particular form of the rogation ceremonies in the face of meteorological adversity, in southwestern Spain, is the transfer to the town of Almonte of the image of the Virgen del Rocío from her hermitage, in the interior of Doñana. The ceremonies of transfers due to drought are documented in the capitular acts of Almonte since 1607, although they do not quantify the intensity of each episode. Regional chronologies are used to develop comparative ordinal indices of severity of recorded annual events. Due to frequency and intensity, the incidence of annual drought during the last two thirds of the 18 th century stands out. The results, obtained through the information of the Virgin's transfers, contribute to the knowledge of the historical climate in the southwestern area of the Iberian Peninsula.
... Atmosphere 2020, 11, 282 2 of 15 the rogations can be found where Catholic religion was established and historical manuscripts were preserved, rogations can be found in different parts of the world as Europe (mainly), America, and old colonies (as Philippines) [15][16][17][18][19][20][21]. Pro-pluvia rogations have been studied, among others, to reconstruct periods of drought in the past [17,19,20,[22][23][24][25][26][27]; to reconstruct seasonal and annual rainfall in the Iberian Peninsula (hereafter IP) from 16th century to 20th century [28]; and, to identify climate extremes [16,29]. Also, Vicente-Serrano & Cuadrat [30] used pro-pluvia and pro-serenitate rogations celebrated in Zaragoza (Spain) as a proxy of the North Atlantic Oscillation (NAO) index. ...
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Rogation ceremonies are religious requests to God. Pro-pluvia rogations were celebrated during dry conditions to ask God for rain. In this work, we have recovered 37 pro-pluvia rogations from 14 documentary sources (e.g.,: ecclesiastical manuscripts, books, and different magazines and newspapers). All of the rogations were celebrated in Extremadura region (interior of southwest of Spain) during the period 1824–1931. Climate of Extremadura is strongly dominated by the North Atlantic Oscillation (NAO). Therefore, pro-pluvia rogations have been associated to the NAO index and the relationship between them has been analyzed. The most relevant results are found in the relationship between pro-pluvia rogations in month n and the positive values of the NAO index for months n-1 and n-2, being statistically significant at 95% confidence level. Thus, the results evidence that the rogation ceremonies of Extremadura are a good proxy for the NAO index.
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This study estimates the pluviometric evolution between the 13th and 19th centuries on the southwestern Iberian Peninsula based on the historic records of the impacts of the Guadalquivir River flooding on the city of Seville (Spain). The main documentary source was “Critical history of the floods of the Guadalquivir in Seville”, published in 1878, which compiles news from different observers, who were contemporaries of each event. Regarding the methodology, it was necessary to transfer the information from different documentary sources to ordinal indices, which required developing allocation criteria per flood impact. From the annual assigned flood index, an interannual series was generated. Moreover, for the last decades of the 21st century, quantifying the flooding levels in the records allowed us to relate them directly to instrumental records of rainfall and establish a relationship between these two phenomena. Through interannual weighing of the flooding indices, it was possible to deduce the durations and intensities of sequences of rainy periods between 1250 and 1850. This allowed us to reconstruct the pluviometric evolution. Of the ten floods classified as most destructive during the five centuries analysed, i.e., from 1280 to 1880, five occurred during little more than a century (1598-1701). The obtained results contribute to knowledge on regional rainfall, as well as to historical climatology and hydrology, over multiple centuries.
Arctic is warming at an alarming speed causing accelerated melting of Greenland and rising of sea level, and geoengineering by injecting aerosol into stratosphere (SAI) has been proposed as a backup approach to mitigate warming. However, studies suggest that SAI implementation may have adverse impacts on global especially monsoon precipitation, and Northern Hemisphere high-latitude injections may have disproportionally high effects than tropical injections. The 1783‒1784 CE Laki eruption in Iceland provides an analogy to study the climatic and the subsequent socioecological responses to Arctic SAI, and China possesses a rich legacy of documents recording climatic disasters and describing their direct impacts on agriculture and society. Using the most recent summer precipitation reconstructions and the documentary data, this study presents a systemic analysis of the hydroclimatic anomalies as well as the societal and ecological consequences in China following the 1783‒1784 CE Laki eruption. The results from multi-proxies show severe drought conditions in eastern China during the post-Laki years, accompanied by large scale locust breakout, famine and human pestilence. The drought and associated disasters first emerged in the North China Plain in 1784 CE, intensified and expanded to the middle and lower reaches of the Yangtze River in 1785 CE. The drought and famine stresses in China are part of the very unsettled climate conditions experienced across the Northern Hemispheric world during the 1780s. By isolating the ENSO-induced precipitation from the reconstructed summer precipitation changes, the results indicate that the Laki eruption did cause severe drought in monsoon China during the next three years. The drought responses in 1783‒1784 were largely counter-balanced by the wetting induced by the concurring strong El Niño event. The results help to enhance our understanding of the hydroclimate consequence of the Northern Hemisphere high latitude volcanic eruption in China, and the potential role climate internal variation such as ENSO may play in modifying volcanic-induced perturbation.
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Instrumental meteorological measurements from periods prior to the start of national weather services are designated “early instrumental data.” They have played an important role in climate research as they allow daily to decadal variability and changes of temperature, pressure, and precipitation, including extremes, to be addressed. Early instrumental data can also help place twenty-first century climatic changes into a historical context such as defining preindustrial climate and its variability. Until recently, the focus was on long, high-quality series, while the large number of shorter series (which together also cover long periods) received little to no attention. The shift in climate and climate impact research from mean climate characteristics toward weather variability and extremes, as well as the success of historical reanalyses that make use of short series, generates a need for locating and exploring further early instrumental measurements. However, information on early instrumental series has never been electronically compiled on a global scale. Here we attempt a worldwide compilation of metadata on early instrumental meteorological records prior to 1850 (1890 for Africa and the Arctic). Our global inventory comprises information on several thousand records, about half of which have not yet been digitized (not even as monthly means), and only approximately 20% of which have made it to global repositories. The inventory will help to prioritize data rescue efforts and can be used to analyze the potential feasibility of historical weather data products. The inventory will be maintained as a living document and is a first, critical, step toward the systematic rescue and reevaluation of these highly valuable early records. Additions to the inventory are welcome.
The objective of this work is to present new meteorological data from southern Spain corresponding to the period 1785‐1830. Data sources are early newspapers and medical studies interested in the influence of environment conditions on health and illness. Data correspond to five cities in the area (Cádiz, Seville, Málaga, Granada, and Cartagena). Around 16.000 new meteorological observations (temperature, pressure, number of rainy days, wind direction, and qualitative statements on rainfall, wind force, cloudiness, fog, and storms) were recorded. Data base obtained is a set of scattered meteorological series, with short periods of observation, fragmented and with no homogeneous characteristics. However, these data may offer an overview on the climatic conditions in the area during the studied period, as well as interesting information on extreme events, as for instance floods in the 1780s decade, and the so‐called ‘year without summer’ 1816.
The attention given by the press to meteorological events, especially to climatic extremes, makes this kind of publication a fundamental source to the study of the climate and weather conditions. The quantity and quality of the news, often associated with detailed descriptions of phenomena and damage, and its broad geographical coverage are just some of the advantages we can find in this type of publication. In this paper, we intend to analyze one of the main Portuguese newspapers and the one with most enduring in the history of our press: The Gazeta de Lisboa. We aim to present a qualitative and quantitative study of all the news about meteorological events concerning Portugal, published in this journal between 1715 and 1762, aiming, not only, to establish patterns of perception and registration variables, but also to prove the importance of the periodical press to the study of climate and weather conditions. © 2018 Universidade de Coimbra - Faculdade de Letras. All rights reserved.
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This study aims at assessing the skill of several climate field reconstruction techniques (CFR) to reconstruct past precipitation over continental Europe and the Mediterranean at seasonal time scales over the last two millennia from proxy records. A number of pseudoproxy experiments are performed within the virtual reality of a regional paleoclimate simulation at 45 km resolution to analyse different aspects of reconstruction skill. Canonical Correlation Analysis (CCA), two versions of an Analog Method (AM) and Bayesian hierarchical modeling (BHM) are applied to reconstruct precipitation from a synthetic network of pseudoproxies that are contaminated with various types of noise. The skill of the derived reconstructions is assessed through comparison with precipitation simulated by the regional climate model. Unlike BHM, CCA systematically underestimates the variance. The AM can be adjusted to overcome this shortcoming, presenting an intermediate behaviour between the two aforementioned techniques. However, a trade-off between reconstruction-target correlations and reconstructed variance is the drawback of all CFR techniques. CCA (BHM) presents the largest (lowest) skill in preserving the temporal evolution, whereas the AM can be tuned to reproduce better correlation at the expense of losing variance. While BHM has been shown to perform well for temperatures, it relies heavily on prescribed spatial correlation lengths. While this assumption is valid for temperature, it is hardly warranted for precipitation. In general, none of the methods outperforms the other. All experiments agree that a dense and regularly distributed proxy network is required to reconstruct precipitation accurately, reflecting its high spatial and temporal variability. This is especially true in summer, when a specifically short de-correlation distance from the proxy location is caused by localised summertime convective precipitation events.
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Weather observations in Zafra during the period 1750 to 1840 have been compiled and studied. Zafra was the capital of the Duchy of Feria, located in the southwest of the Iberian Peninsula. The documentary sources used in this work are weekly reports submitted to the Duke (who lived in Madrid) that contain a section describing the weather of the preceding week or less. Regular and updated meteorological information was vital to the government of this Duchy as farming and ranching constituted the bases of the economic activity in this region, allowing the estimation of crop yield and quality and a better management of the trade of agricultural products. Therefore, this documentary source is exceptional to study the climate of SW Iberia due to its continuity, homogeneity and high temporal-resolution.
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A renewed interest on the impacts of climate change has spurred several studies on climate/health relationships. This study aims to detect and explain any changes in the relationships between climate and mortality in Lisbon from 1835 until 2012. The evaluation of mortality seasonal rhythms over time is based on the 100-Index per decades, annual Winter-Summer ratio, as well as other descriptive statistics. A change in the seasonal rhythm of mortality over the last 177 years was found. In the mid-19th century mortality peaked in summer, whereas in the 1890s and the 1900s there was slight monthly variability. On the contrary, a winter maximum has occurred since the 1940s, although a secondary summer peak of mortality may emerge during the most severe heat-waves. Although long term positive temperature trends were confirmed, no systematic positive mortality trends were found in the last three decades. The results suggest that mortality rhythm changes during the 19th and 20th century are not directly related to climatic reasons alone (except in the case of extreme weather events), but rather to improvements in hygienic, sanitary and nutrition conditions and advances in medicine. However, given the possible increase of summer heat waves in the future, and individuals increasing vulnerability, particularly in urban areas, such secondary peaks of mortality will tend to happen more frequently, unless adaptation of populations to hotter conditions takes place and/or measures are taken to protect people from high temperatures.
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A calibration of reconstructed winter, spring and autumn precipitation series in Portugal from 1600 onwards is undertaken in the present study using new instrumental sources for the period of 1815–2012. As summer precipitation in Portugal is scarce and irregular, it is not considered. A consistency analysis of the calibrated time series is then undertaken using: (1) precipitation indices for Portugal in 1675–1799; (2) teleconnections between seasonal precipitation and large-scale atmospheric flow; (3) two paleoclimatic experiments (ERIK1 and ERIK2), generated from a global/regional climate model chain (ECHO-G/MM5); and (4) tree-ring records from oak trees in Portugal (Serra do Buçaco). These are the first multi-centennial records of tree-ring growth in Portugal (the earliest series begin in 1675). General agreement is found between indices and calibrated precipitation for their common period on an annual basis. Overall, the atmospheric teleconnection patterns are dynamically coherent between the inst
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July-to-October temperature variations are reconstructed for the last 800 years based on tree-ring widths from the Cazorla Range. Annual tree-ring width at this site has been found to be negatively correlated with temperature of the previous summer. This relationship is genuine, metabolically plausible, and cannot be explained as an indirect correlation mediated by hydroclimate. The resulting reconstruction (NCZ Tjaso ) represents the southernmost annually resolved temperature record based on tree-rings in Europe and provides detailed information on the regional climate evolution during the Late Holocene in the southeast of the Iberian Peninsula. The tree-ring based temperature reconstruction of Cazorla Range reveals predominantly warm summer temperatures during the transition between the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) from the 13th to the mid of the sixteenth century. The LIA spanned a slightly longer time (1500–1930 CE) than in other European summer temperature reconstructions from the Alps and Pyrenees. The twentieth century, though warmer than the preceding centuries, does not show unprecedented warmth in the last 800 years. Three ensembles of climate simulations conducted with two global atmosphere–ocean general circulation climate models (GCMs), considering different external forcings, were used for comparison: ECHO-G (Erik) and MPI-ESM (E1 and E2). Additionally, individual simulations were available from GCM included in the fifth Coupled Model Intercomparison Project, as well as single-forcing simulations performed with MPI-ESM. The comparison of the reconstructed and simulated temperatures revealed a close agreement of NCZ Tjaso with the simulations performed with total solar irradiance forcing with wider amplitude. Furthermore, the correlations with single-forcing simulations suggest volcanism as the main factor controlling preindustrial summer temperature variations in the Cazorla Range over the last five centuries. The persistent anti-correlation between NCZ Tjaso and simulated temperatures during the MCA–LIA transitional period underlines the current limitations for attributing temperature variations during that period to internal variability or external forcing.
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This chapter reviews the scientific evidence published since the IPCC Fourth Assessment Report (AR4) on observed and projected impacts of anthropogenic climate change in Europe and adaptation responses. The geographical scope of this chapter is the same as in AR4 with the inclusion of Turkey. Thus, the European region includes all countries from Iceland in the west to the Russian Federation (west of the Urals) and the Caspian Sea in the east, and from the northern shores of the Mediterranean and Black Seas and the Caucasus in the south to the Arctic Ocean in the north. Impacts above the Arctic Circle are addressed in Chapter 28 and impacts in the Baltic and Mediterranean Seas in Chapter 30. Impacts in Malta, Cyprus, and other island states in Europe are discussed in Chapter 29. The European region has been divided into five sub-regions (see Figure 23-1): Atlantic, Alpine, Southern, Northern, and Continental. The sub-regions are derived by aggregating the climate zones developed by Metzger et al. (2005) and therefore represent geographical and ecological zones rather than political boundaries. The scientific evidence has been evaluated to compare impacts across (rather than within) sub-regions, although this was not always possible depending on the scientific information available. 23.1.1. Scope and Route Map of Chapter, The chapter is structured around key policy areas. Sections 23.3 to 23.6 summarize the latest scientific evidence on sensitivity climate, observed impacts and attribution, projected impacts, and adaptation options, with respect to four main categories of impacts: • Production systems and physical infrastructure • Agriculture, fisheries, forestry, and bioenergy production • Health protection and social welfare • Protection of environmental quality and biological conservation The benefit of assessing evidence in a regional chapter is that impacts across sectors can be described, and interactions between impacts can be identified. Further, the cross-sectoral decision making required to address climate change can be reviewed. The chapter also includes sections that were not in AR4.
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– Low -frequency variability is a good starting point for modelling the climate system and understanding mechanisms that can give us some indication of future climate evo-lution. this work aims to better understand the degree of association between the atmospheric circulation and precipitation over europe and the iberian Peninsula. to achieve this goal, the standard precipitation anomalies in europe and the anomalies of sea level pressure (sLP) in the north atlantic region during the twentieth century were subjected to Multi -Channel singular spectrum analysis (Mssa). this procedure allows us to measure the degree of association between the sLP and precipitation fields. the identification of common oscillations between the two climatic fields led not only to the confirmation of the physical meaning of these oscilla-tions, but also to the identification of the dynamical evolution of the ocean -atmosphere system in the north atlantic. two oscillations, statistically significant, common to both the precipita-tion field and sLP field were isolated with periods of about 8 years and 5.3 years. the 8 -year oscillation is the most significant and robust of the two climatic fields and exhibits a classic naO pattern, with an out -of -phase variability between northern and southern parts of the do-main. furthermore, it is characterized by a westward propagation of the climate signal and a perfect out -of -phase variability between the precipitation and sLP. the 8 -year oscillation is also very significant in the iberian Peninsula and is associated with dry winters and wet winters, whose sequence was identified for the twentieth century. the 5.3 -year oscillation is related to the east atlantic Pattern that exhibits another dipolar structure, with an out -of -phase variability between southwest and northwest europe. the regularity of the 8 year oscillation can be antici-pated with a degree of certainty, thus permitting a prediction of the occurrence of wet and dry years and allowing for a better management of water resources. Resumo – oscilAções interAnuAis dA PreciPitAção invernAl nA euroPA. o cAso dA Penín‑ sulA ibéricA. a variabilidade de baixa frequência é um bom indicador para modelizar o sistema climático e apreender mecanismos que dêem indicações sobre evolução futura do clima. Com este trabalho pretende -se compreender melhor a relação entre a circulação atmosférica e a pre-recebido: Janeiro, 2010. aceite: fevereiro, 2011.
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Among the different meteorological hazards, droughts are those with the highest socio-economical impact on the Iberian Peninsula. Drought events have been largely studied in the instrumental period, but very little is known about the characteristics of droughts in the preinstrumental period. In this work, several series of rogation ceremonies are used to identify severe droughts within the period 1750-1850. The overlapping of the rogation series with some instrumental series served to identify some climatic characteristics of rogation ceremonies: (a) during spring, rainfall deficits needed to celebrate rogation ceremonies are smaller than in any other season; (b) the hydrological deficit in a particular region increases with the number of locations celebrating rogations simultaneously. On the other hand, it was found that between 1750-1754 and 1779-1783 are probably the driest periods of the 101 analyzed years. Both show an important number of rogations all over Iberia and during all the seasons. The most extended drought of this period occurred during the spring of 1817, affecting 15 of the 16 locations studied. This drought was influenced by the Tambora eruption (1815). The study of the climate footprint of this eruption and its comparison with similar situations in the series suggest that the spring drought of 1824 may be associated with the eruptions of the Galunggung and Usu volcanoes (1822). Further studies are required to confirm this fact and understand the atmospheric mechanisms involved.