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The difference between Johansson's (1932) series (IBU-old) and the newly obtained dates: a comparison with respect to each event, that is, (a) when the ice started melting (IBU1), (b) when the river was free of ice (IBU2) and (c) the arrival of the Halinen ice (IBU3).
Source publication
Ice breakup (IBU) observations have been recorded for Aura River in Turku, southwest Finland, since the mid-18th century. The latest long-term investigation covered the period 1749–1906, but the series contains several biases. In this article, we present a fully revised and extended IBU series (1749–2018) of Aura River for climate research purposes...
Contexts in source publication
Context 1
... more detailed comparison (Figure 3) between the IBU records showed that the IBU-old dates were identical to our new IBU1, IBU2 and IBU3 dates in 16, 86 and 17 out of 95, 156 and 57 cases, respectively. That is, in 55% of the cases, the IBU-old record agreed with our IBU2 dates. ...
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Citations
... Today, with global warming in mind, one of the key topics in potamology (the study of rivers) is the assessment of changes in thermal conditions and the occurrence of ice phenomena, as confirmed by numerous publications on the subject [11][12][13][14]. ...
In the context of ongoing environmental changes, particularly against the backdrop of global warming, significant attention is being given to areas of exceptional natural value that, in many aspects, retain a pristine character. One such area is the Biebrza River in northeastern Poland, which, together with the wetlands in its basin, forms one of the most valuable ecosystems of its kind in Europe. This study analyses the changes in the thermal and ice regime for two hydrological stations, Sztabin and Burzyn, in the period from 1959 to 2023. It was found that the average annual water temperature in this period for the Biebrza River increased by 0.28 °C/decade, and in the case of ice phenomena, statistically significant changes for both stations showed a decline, with an acceleration of the ice cover disappearance by an average of 3 days/decade. These recorded changes should be considered unfavourable, as they will affect the transformation of both the biotic and abiotic characteristics of the river itself, as well as the natural elements associated with it.
... In winter, river discharge decreases as temperatures drops and snow accumulates, leading to ice coverage. While rivers usually freeze annually, recent years have witnessed open-channel periods lasting through winter (Norrgård and Helama, 2019). The wintertime is succeeded by spring snowmelt, causing a peak in runoff and discharges. ...
... It is possible that in December it was difficult to reach the island, whereas in February the sea ice could be strong enough to allow the relatives to reach the island by sledge and hold the funeral. Although there is some evidence of the climate beginning to warm in Southwestern Finland in the 18th century (Norrgård & Helama, 2019), there are no precise climate records from the period. It is therefore impossible to say whether winter temperatures were significantly different at the time of each burial. ...
Moilanen, U. & Paasikivi, S. 2023. Source discrepancies in post-medieval archaeology – a case study of crypt burials at Seili church, Finland. Mortality, https://doi.org/10.1080/13576275.2023.2174840
The island of Seili, in the south-western archipelago of Finland, is famous for its history as a leprosy colony and mental asylum. The island formed a small, hierarchical community run by priests and hospital officials. In this article, we examine the history of the burial crypt in Seili church by comparing information from historical documents and observations made during archaeological fieldwork. The material gathered from these two sources is conflicting, suggesting an interesting history in the use of the burial crypt. It seems that women’s coffins could easily be moved elsewhere from the crypt when new coffins belonging to males were interred. It is argued that identifying the buried individuals would be necessary
for a taphonomic study of the mummification processes and ensuring that the information about the crypt is based on facts. However, the identification is difficult due to inconsistent historical records. This underlines the importance of Post-Medieval archaeology in studying sites connected to family histories.
... While not analyzed on the large scale yet, extensive compilations of ice phenology of water bodies from the Russian Empire dating back to 1530 (Daugava River, Riga) exist. Some of the 30 therein included ice-break-up series like the Tornio River (Loader et al., 2011) or the Aura River (Norrgård and Helama, 2019) are well known and investigated. However, most of them are entirely novel discoveries with great potential for future research (Rykachev, 1886;Shostakovich, 1909). ...
Climatic variations have impacted societies since the very beginning of human history. In order to keep track of climatic changes over time, humans have thus often closely monitored the weather as well as natural phenomena influencing everyday life. Resulting documentary evidence from archives of societies enables invaluable insights into the past climate beyond the timescale of instrumental and early instrumental measurements. This information complements other proxies from archives of nature such as tree rings in climate reconstructions, as documentary evidence often covers seasons (e.g., winter) and regions (e.g., Africa, Western Russia, and Siberia, China) that are not well covered with natural proxies. While a mature body of research on detecting climate signals from historical documents exists, the large majority of studies is confined to a local or regional scale and thus lacks a global perspective. Moreover, many studies from before the 1980s have not made the transition into the digital age and, hence, are essentially forgotten. Here, I attempt to compile the first-ever systematic global inventory of documentary evidence related to climate extending back to the Late Medieval Period. It combines information on past climate from all around the world, retrieved from many studies on historical documentary sources. Historical evidence range from personal diaries, chronicles, administrative/ clerical documents to ship logbooks and newspaper articles. They include records of many sorts, e.g., tithes records, rogation ceremonies, extreme events like droughts and floods, as well as weather and phenological observations. The inventory, published as an electronic supplement, comprises detailed event chronologies, time series, proxy indices, and calibrated reconstructions, with the majority of the documentary records providing indications on past temperature and precipitation anomalies. The overall focus is on document-based time series with significant potential for climate reconstruction. For each included record series, extensive meta information and directions to the data (if available) are given. To highlight the potential of documentary data for climate science three case studies are presented and evaluated with different global reanalysis products. This comprehensive inventory promotes the first-ever global perspective on historical documentary climate records and, thus, lies the foundation for incorporating historical documentary evidence into climate reconstruction on a global scale, complementing early instrumental measurements as well as natural climate proxies.
... the Aura River series from southern Finland (Norrgård and Helama, 2019), but the series has not yet 65 been compared to any other ice phenology series. The Torne River and Aura River series are unique in comparison to the Finnish lake-ice series because of their length. ...
... Structures such as bridges, industrial outlets and the use of ships to break the ice may advance or delay the ice breakup process (e.g. Norrgård and Helama 2019;Sharma et al., 2016;Kajander, 1993). Moreover, while lake ice breakup 100 dates are mainly determined by temperature the breakup process in rivers link to both temperature and precipitation. ...
... Within the city limits, the width of Aura River varies between 35 and 100 meters. The Aura River series depicts the ice-off date, which is when the river is ice free between the mouth of the river and Halinen dike (Norrgård and Helama, 2019). The dike is situated six kilometres from the mouth of the river and it is mentioned for the first time in the 14 th century. ...
In Finland, ice breakup observations have been recorded for centuries for Aura River (1749–2020), Torne River (1693–2020) and Kokemäki River (1793–2020). The Kokemäki River is a newly revised, extended, and updated ice breakup series from Pori. The Spearman analysis shows that the correlation between Aura and Kokemäki rivers is strong, while the correlation between the two southern rivers (Aura and Kokemäki) and Torne River is weaker. The difference is attributed to the longitudinal distance between the rivers. Temperature correlations are strong for all three rivers and the long-term trends towards earlier breakups are statistically significant. Aura and Kokemäki rivers show considerable changes. Aura and Kokemäki river have had two respectively three years without a complete ice cover in the 21st century. These are the first non-freeze events in over 270 years of recorded observations. In Torne River, however, the earliest recorded breakup date has changed only marginally the last 100 years. Moreover, the earliest recorded breakup date in the 21st century occurred only five days earlier than the earliest breakup date in the 18th century. Kokemäki River did not escape the hydroelectric power plant boom in the mid-1900s, and this has speeded up the breakup process. A qualitative analysis shows that exceptionally late ice breakups occurred in all three rivers in 1807, 1810 and 1867. There are noticeable clusters of late events in the early 1800s in all three series, while an exceptionally early breakup event occurred in Aura and Kokemäki rivers in 1822.
... Our aim is to provide a better understanding of Leche's background and his climatic interest, which we also believe explains his dendroclimatological perspective and reasoning. Previous research has focused on Leche's achievements in botany, agriculture, and horticulture (Väre 2008); his general studies in climatology (Johansson 1913;Holopainen 2004;Holmberg 2012); and his contributions to phenology (Väre 2008) and cryophenology (Norrgård and Helama 2019). Here, however, we will discuss Leche's dendrochronological insights, which, to our knowledge, have never been cited. ...
Cross-dating is considered one of the most important principles of dendrochronology. The first known cross-dating attempts, conducted between the years 1737 and 1783 by independent researchers in France, Germany, and Sweden, were related to the identification of growth rings believed to have formed during the harsh winter of 1708–1709. In this paper, we present a novel perspective on the birth of dendrochronology and cross-dating in the 1700s. We focus on the ideas and experimental studies of one of the lesser known pioneers, Johan Leche (1704–1764), the Professor of Medicine at the Royal Academy (Turku, Finland). Instead of winter harshness, Leche was fascinated by the drought that killed and damaged several trees and tree species in the summer of 1757. Leche conducted several dendrochronological and field experiments described only in his unpublished manuscript filed in the National Archives in Sweden. Reviewing Leche’s measurements of ring-width series of multiple radii and his comparisons between the radii, it seems only fair to include him in the long list of natural historians who made important contributions to the field of dendrochronology. His manuscript was never published, which is why Leche’s dendrochronological experiments and recommendations never reached a wider audience.
... More generally, the signals of spring advance have been reported in Finnish phenological studies for trees, shrubs, grasses, agricultural plants, migratory birds, and insects (Lappalainen et al. 2008;Linkosalo et al. 2009;Holopainen et al. 2013) as well as for lake and river ice breakups Korhonen 2019;Norrgård and Helama 2019). Obtained from data representative of plant and animal kingdoms, biotic and abiotic phenomena and over various time intervals, these studies add to the accumulating evidence suggesting various types of natural systems being largely driven by a common climatic forcing. ...
Plant phenological dataset collected at 42 sites across the mainland of Finland and covering the years 1997–2017 is presented and analysed for temporal trends. The dataset of n = 16,257 observations represents eleven plant species and fifteen phenological stages and results in forty different variables, i.e. phenophases. Trend analysis was carried out for n = 808 phenological time-series that contained at least 10 observations over the 21-year study period. A clear signal of advancing spring and early-summer phenology was detected, 3.4 days decade−1, demonstrated by a high proportion of negative trends for phenophases occurring in April through June. Latitudinal correlation indicated stronger signal of spring and early-summer phenology towards the northern part of the study region. The autumn signal was less consistent and showed larger within-site variations than those observed in other seasons. More than 60% of the dates based on single tree/monitoring square were exactly the same as the averages from multiple trees/monitoring squares within the site. In particular, the reliability of data on autumn phenology was increased by multiple observations per site. The network is no longer active.
... Turcotte et al. [48] have stated that future earlier spring snowmelt periods influence the break-up process as the ice cover is less exposed to short-wave radiation (the sun angle increases over time) when the discharge begins to rise. Based on long-term data sets, changes towards earlier break-up dates have also been observed in Northern (polar/subarctic region) and Southern Finland (boreal region) [49][50][51]. Thus, an increasing potential for mechanical break-ups and higher ice-jam-induced water levels are expected [48]. ...
Predicting the future changes in river ice development and impacts on seasonal sediment transport requires more in-depth examination of present river ice cover growth processes. This paper therefore investigates: (1) the impacts of hydro-climatically varying years on river ice development in a Scandinavian subarctic meandering river and (2) the accuracy of existing analytical models for predicting ice thickness growth and ice decay. Stefan’s ice growth equation (version by Michel et al.) and Bilello’s ice decay equation are applied to varying hydro-climatic conditions experienced in the years 2013–2019. Estimates from these equations are compared with observed field conditions such as ice thicknesses, ice clearance dates and freeze-thaw days. Overall, the equations were most accurate in the winter of 2016–2017 when the maximum mid-winter snow thickness value was high, the number of freeze-thaw days was the closest to the long-term average of northern Scandinavia, and the rate of thermal snow-melt in the subsequent spring was slow. The equations would need to be adjusted to take into account expected future changes to conditions such as shorter winters, less snow formation and increased frequency of air temperatures crossing 0 °C.
Libraries have a direct influence on digital humanities (DH) research projects that utilize digitized newspapers from their collections. However, a library’s level of participation in a project will vary and may range from resource provider to active collaborator. Libraries must manage the different expectations of each project; thus, a variety of services are needed.
The National Library of Finland continuously aims to improve its services and provide researchers with broader access to digitized collections. The library’s DH research team has extensive experience in research projects, and they actively support the work of DH researchers. In this paper, I present an overview of the experiences of the DH research team. I focus on projects that have used digitized historical newspapers and journals, and I outline a range of potential problems and suggest possible solutions.
At high latitudes, long-term changes in riverine ice break-ups are exemplary measures of climatic change and variation. This study compares cryophenological trends, patterns and changes for the rivers Aura (1749–2020), Torne (1693–2020) and Kokemäki (1793–2020); all sites are located in Finland. The Kokemäki River series is a new series from the city of Pori. The findings show statistically significant cross-correlations between the Aura and Kokemäki rivers but weaker cross-correlations with the Torne River. We attribute the latter to climatic differences caused by the higher latitude of the Torne River. Taken together, the many results of this study suggest that the spring climate in the south has changed more rapidly and become less predictable than in the north. Climatic extremes – warmer and wetter winters – in the 2000s resulted in the first recorded no-freeze events on the Aura and Kokemäki rivers. This was the culmination of a rapid increase in early ice break-up events and interannual variability over the last 30 years. The number of early events has increased in all three rivers since the early or mid-1900s, but the earliest recorded break-up day on the Torne River has changed only marginally in the last 100 years. Our dynamic temperature analysis shows that the ice break-up on the Torne River requires higher temperatures than in the south, and future changes in the timing of the break-up depend on April temperatures. In the south, on the other hand, future changes concerns the return period of no-freeze events, which depend on temperature and precipitation during winter.
