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Extreme dry and wet spell analysis across Europe. (a), (b) Duration of extreme dry (wet) spells. (c), (d) Changes in the duration of extreme dry (wet) spells as percentage change per decade with reference to the duration in 1958. (e), (f) Average within-year timing of extreme dry (wet) spells in the period 1958–2017. (g), (h) Changes in the within-year timing of extreme dry (wet) spells as days per decade with reference to the timing in 1958. Results of (c), (d), (g) and (h) are shown as means across hexagons. Black dots represent the rain gauges examined with locally significant (green) and field significant (magenta) sites.
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Dry spells are sequences of days without precipitation. They can have negative implications for societies, including water security and agriculture. For example, changes in their duration and within-year timing can pose a threat to food production and wildfire risk. Conversely, wet spells are sequences of days with precipitation above a certain thr...
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Citations
... The occurrence of periods with no precipitation has many harmful effects on the population, including on water security and agriculture. As evidenced by many researchers [8][9][10], an understanding of changes in their duration and in the annual cycle is necessary to control ...
This study provides a climatological analysis of annual and long-term variability of dry days and sequences of dry days in the Polish Carpathians between 1986 and 2020. The input data for the research was compiled from the daily precipitation totals from 17 meteorological stations and the T. Niedźwiedź catalogue of circulation types over southern Poland. The frequency of sequences of dry days of different duration has been presented. The incidence of long-term periods has been related to the atmospheric circulation. The number of dry days and the averages of both the number and of the duration of sequences of dry days were analysed for the study period. This yielded an average annual number of dry days ranging from 142 to 195 (39–53% of days in a year), depending on the altitude above sea level and longitude. A general pattern emerged in which the number of dry days increased from west to east. At most stations, there were no statistically significant trends with respect to the dry day characteristics analysed. This is an obvious result of high year-to-year variability, which means that only large changes can achieve statistical significance. Dry days have been evidenced to relate to circulation types. The vast majority of dry days are related to anticyclonic systems, particularly the anticyclonic wedge (Ka) and western anticyclonic (Wa) situations. On the other hand, no clear-cut relationship was established between an increase in air temperature and the occurrence of dry days.
... Further, the recent multi-season drought episodes of 2016-2018 in southern India were found to be associated with unprecedented low northeastern monsoon rainfall (Mishra et al., 2021). Using a homogeneous global station-based daily precipitation dataset (Global Historical Climatology Network Data-GHCN-Daily) of over 5000 rain gauges during 60 years (1958─2017), Breinl et al. (2020) reported that the duration of annual maximum dry spells showed an increasing trend across several locations, while the shift in dry spell timings are field significant. In their study, however, no records were available for the Indian sub-continent. ...
Knowledge of drought onset and its relationship with drought severity (deficit volume) is crucial for providing timely information for reservoir operations, irrigation scheduling, devising cropping choices and patterns and managing surface and groundwater water resources. An analysis of the relationship between drought onset timing and deficit volume can help in drought hazard assessments and associated risks. Despite its importance, little attention has been paid to understand the drought onset timing and its potential linkage with deficit volume for effective drought monitoring and its impact assessment. Further, only a few studies have explored the role of environmental controls, encompassing the interaction between climate, catchment and land-surface processes in influencing streamflow droughts and associated characteristics such as onset time and severity. This study leverages quality-controlled stream-flow observations from 1965 to 2018 to unveil regional patterns of streamflow drought onset, at-site trends in deficit volume and detect non-linear relationships between onset timing and deficit volume across 82 rain-fed catchments in peninsular India (8-24 N, 72-87 E). We show that around 12% of catchments show an earlier onset of streamflow droughts in conjunction with a decreasing trend in deficit volume. Further, approximately one-third of the catchments show a significant non-linear dependency between drought deficit volume and onset time. Among catchment controls, such as soil and topographic properties, we found soil organic carbon stock and stock as dominant drivers controlling the streamflow drought onset time. Likewise, sand content and vertical distance to channel network control the stream-flow deficit volume. Finally, the linkages between inferred dominant low-flow generation mechanisms and the specific combinations of environmental controls are synthesized in a conceptual diagram that might assist in developing appropriate models for low-flow simulations and predictions, especially across ungauged sites.
... Extreme dry spells contribute to meteorological, agricultural, and hydrological droughts. Dry spells negatively affect water quality, and in combination with high temperatures, they can cause toxic algal blooms, which also decrease the oxygen content in the water [11][12][13], threatening the lives of fish and other aquatic organisms. Prolonged wet weather, on the other hand, may favor flooding. ...
... However, in the Netherlands, dry periods are longer during both the warm and cold seasons. Breinl et al. [11] analyzed the most extended dry spells in Western, Southern, and Northern Europe. They have shown that the declining trends dominate in Northern Europe, while in Southern and Central Europe they are very diverse. ...
The aim of this study is to present the spatial and temporal variability of the frequency of dry and wet days and dry and wet spells against the background of changes in precipitation and atmospheric circulation. The study is based on daily precipitation totals from 46 meteorological stations in Poland from 1966 to 2023. Additionally, seven circulation indices were used, namely GBI, NAO, AO, EA, EA/WR, SCAND, and AMO. Dry days are defined as days without precipitation. Wet days are days with at least 1 mm of precipitation. It was shown that dry spells are much more common than wet spells, are longer, and cover larger areas. Long-term changes in the annual characteristics of dry and wet days and spells are not statistically significant. Only the length of the most extended dry spell in the year increases. However, there are significant changes in their annual cycles. Spring is drier; in summer, precipitation decreases in the south and increases in the north; November and December, symbols of gloomy rainy weather, are increasingly drier; and rainy weather has shifted to January and February. The impact of circulation varies according to the season, with the NAO, AO, SCAND, and GBI indices having the greatest influence.
... 2.2.1. The Determination of Dry/Wet Days and Warm/Cold Seasons Dry days are characterized by daily total precipitation amounts less than 0.1 mm, while wet days refer to periods when the daily total precipitation is 0.1 mm or more [59]. In this study, a threshold of 0.1 mm has been employed to classify wet and dry days. ...
This study aims to reveal the long-term station-based characteristics of precipitation in Istanbul, a mega city located on the continents of Europe and Asia, with complex topography and coastline along the Marmara and Black Seas. Using data from five different stations, three located in the European continent and two in the Asian continent, with measurement periods ranging from 72 to 93 years, wet and dry days have been identified, statistics on precipitation conditions during the warm and cold seasons have been generated, categorization based on precipitation intensities has been performed, and analyses have been conducted using extreme precipitation indices. At stations located in the northern part of the city, higher annual total precipitation has been observed compared to those in the south. A similar situation applies to the number of wet days. While during the cold season, the wet and dry day counts are nearly the same across all stations, this condition exhibits significant differences in favor of dry days during the warm season. Apart from dry conditions, "moderate" precipitation is the most frequently observed type across all stations. However, "extreme" events occur significantly more often (6%) during the warm season compared to the cold season (2%). Long-term anomalies in terms of annual precipitation totals have shown similarity between stations in the north and south, which has also been observed in longitudinally close stations. Despite the longer duration of the cold season and stronger temperature gradients, extreme rainfall events are more frequent during the warm season, primarily due to thunderstorm activity. While trend analyses revealed limited significant trends in precipitation intensity categories and extreme indices, the study highlights the importance of comprehensive examination of extreme rainfall events on both station-based and regional levels, shedding light on potential implications for regional climate change. Lastly, during the cold season, the inter-station correlation in terms of annual total precipitation amounts has been considerably higher compared to the warm season.
... Extreme dry spells contribute to meteorological, agriculture and hydrological droughts. Dry spells negatively affect water quality, and in combination with high temperatures, they can cause toxic algal blooms, which additionally result in the oxygen content decrease in the water [11][12][13], threatening the live of fishes and other aquatic organisms. Prolonged wet weather, on the other hand, may favor flooding. ...
... Zolina et al. [10] have found that the duration of dry spells decreases over Scandinavia and in southern Europe in both winter and summer, but over the Netherlands dry periods are longer also during both warm and cold seasons. Breinl et al. [11] analysed the longest dry spells in western, southern and northern 2 Europe. They have shown that in northern Europe decreasing trends dominate, in southern Europe on Peninsula increasing trends dominate and in central Europe the picture is very diverse. ...
The aim of this study is to present the spatial and temporal variability of the frequency of dry and wet days and dry and wet spells against the background of changes in precipitation and atmospheric circulation. The study is based on daily precipitation totals from 46 meteorological stations in Poland for the years 1966-2023. Additionally seven circulation indices were used: GBI, NAO, AO, EA, EA/WR. SCAND ana AMO. Dry days are defined as days without precipitation. Wet days are days with at least 1 mm of precipitation. It was shown that dry spells are much more common that wet spells, are longer and cover larger areas. Long term changes in annual characteristics of dry and wet days and spells are statistically insignificant. Only the length of the longest dry spell in the year increases. However, there are significant changes in their annual cycles. Spring is drier, in summer months, precipitation decreases in the south and increases in the north, November and December, symbols of gloomy rainy weather, are increasingly drier, rainy weather moved to January and February. The impact of circulation varies with seasons and NAO, Ao, SCAN and GBI indices have the strongest impact.
... According to Breinl et al. (2020), dry areas mean low soil moisture that cannot support agriculture hence calling for planned and targeted application of adaptation measures by stakeholders. The variation in drought events across the study districts could be explained by difference in altitude where Nakasongola is at a lower altitude and whose location has been projected to experience reduction in annual and seasonal rainfall especially under RCP4.5 (Mulinde et al. 2022). ...
The cattle corridor in Uganda is known for its vulnerability to unpredictable rainfall patterns, recurring and severe droughts, all of which lead to water scarcity and crop failures. Therefore, to gain a deeper understanding of these drought characteristics, three districts were selected within the cattle corridor: Rakai in the South, Nakasongola in the Central, and Nabilatuk in the North. An analysis of historical and near future meteorological drought changes in the cattle corridor using SPI from the Coordinated Regional Downscaling Experiments (CORDEX) for the historical periods 1981–2010 and 2031–2060 (RCP 4.5 and 8.5). Trends in SPI values were assessed using the Sen slope estimator and Mann–Kendall test at 0.05. Results suggest ongoing drought occurrences, even during traditionally wet periods, especially during La Niña period. Nakasongola district experienced more frequent droughts, with 25 in the historical period and 26 in the near future compared to Rakai and Nabilatuk districts. Historically, the districts had average drought spans of 7–9 months and maximum spans of 23–36 months. Under RCP4.5, durations ranged from 6 to 11 months (average) and 34–60 months (maximum), while under RCP8.5, from 8 to 13 months (average) and 23–41 months (maximum). Drought severity and duration were expected to increase across all districts, with Rakai district facing the longest historical (January 2007–December 2009) and the projected (April 2054–March 2059) droughts. Additionally, Nabilatuk showed negative and significant SPI trends historically (Sen’s slope = − 004, p value = 0.004). Hence, tailored interventions are crucial for stakeholders managing drought to build resilience.
... Inorganic compounds of concern include iron and manganese that can originate from the source water and/or be released from the pipe wall due to corrosion reactions or hydraulic events [53]. Organic substances may be a result of heavy precipitation following long dry periods [54][55][56]. Prolonged dry spells cause the soil to become compact and retain contaminants, which when followed by an intense rainfall event, allows for overland runoff into sources of drinking water, increasing turbidity and pathogen loads [57][58][59]. Such events have the potential to overwhelm drinking water treatment processes, allowing pathogens to pass through to the distribution system and ultimately to residents' homes where they are ingested [12,60]. ...
Extreme precipitation events are occurring more intensely in Canada. This can contaminate water sources with enteric pathogens, potentially increasing the risk of acute gastrointestinal illness. This study aimed to investigate the relationship between extreme precipitation and emergency department (ED) visits for acute gastrointestinal illness in Toronto from 2012 to 2022. Distributed lag non-linear models were constructed on ED visit counts with a Quasi Poisson distribution. Extreme precipitation was modelled as a 21-day lag variable, with a linear relationship assumed at levels ≧95th percentile. Separate models were also conducted on season-specific data sets. Daily precipitation and gastrointestinal illness ED visits ranged between 0 to 126 mm, and 12 to 180 visits respectively. Overall, a 10-mm increase in precipitation >95th percentile had no significant relationship with the risk of ED visits. However, stratification by seasons revealed significant relationships during spring (lags 1–19, peak at lag 14 RR = 1.04; 95% CI: 1.03, 1.06); the overall cumulative effect across the 21-day lag was also significant (RR = 1.94; 95% CI: 1.47, 2.57). Extreme precipitation has a seasonal effect on gastrointestinal health outcomes in Toronto city, suggesting varying levels of enteric pathogen exposures through drinking water or other environmental pathway during different seasons.
... Increased rainfall variability includes increases in extreme daily precipitation (e.g. R95pTOT, RX1day and RX5day) across the globe (Alexander et al., 2006;Min et al., 2011;Kharin et al., 2013;Westra et al., 2013Westra et al., , 2014Donat et al., 2016) and increased length and frequency of dry spells in eastern, central and southern Europe, western and south-western United States, South America, parts of Asia and parts of Africa (Bouagila & Sushama, 2013;Jacob et al., 2014;Singh et al., 2014;Marengo et al., 2016;Breinl et al., 2020). Increased rainfall variability may also interact with increased temperatures and evapotranspiration (ET) to further compound changes in water availability (Konapala et al., 2020). ...
... The majority of the savanna biome's global distribution has highly variable rainfall, both within and across years, and this variability is predicted to increase with climate change (Krishna Prabhakar, 2022). Studies across the globe (Jacob et al., 2014;Singh et al., 2014;Marengo et al., 2016;Breinl et al., 2020), including Africa (Usman & Reason, 2004;MacKellar et al., 2014;Mengistu et al., 2021), have shown a decrease in the number of rainy days and an increase in the frequency of growing season dry spells. While the mechanisms of how prerain green-up provides an opportunity for trees to grow without competition from grasses (temporal niche separation) and contributes to tree-grass coexistence have been relatively well documented in savannas (Scholes & Walker, 2004;Higgins et al., 2011;, only a few studies have explored how treegrass interactions are likely to be affected by the increased variability in rainfall patterns expected with climate change. ...
Increasing rainfall variability is widely expected under future climate change scenarios. How will savanna trees and grasses be affected by growing season dry spells and altered seasonality and how tightly coupled are tree–grass phenologies with rainfall?
We measured tree and grass responses to growing season dry spells and dry season rainfall. We also tested whether the phenologies of 17 deciduous woody species and the Soil Adjusted Vegetation Index of grasses were related to rainfall between 2019 and 2023.
Tree and grass growth was significantly reduced during growing season dry spells. Tree growth was strongly related to growing season soil water potentials and limited to the wet season. Grasses can rapidly recover after growing season dry spells and grass evapotranspiration was significantly related to soil water potentials in both the wet and dry seasons. Tree leaf flushing commenced before the rainfall onset date with little subsequent leaf flushing. Grasses grew when moisture became available regardless of season.
Our findings suggest that increased dry spell length and frequency in the growing season may slow down tree growth in some savannas, which together with longer growing seasons may allow grasses an advantage over C3 plants that are advantaged by rising CO2 levels.
... Dry spells pose a threat to food production, water quality, and drinking water for local communities, and would increase desertification in Nigeria, especially in the southwestern area where it is more intense. Dry spells lower river flows, reduce velocities, and enhance the potential for toxicity (Breinl et al., 2020). ...
The little dry season (LDS), a phenomenon of interest in West Africa is associated with a dry spell amid the wet season and is consequential to agriculture and global food production. However, the current literature suffers a knowledge gap on rainfall extremes and trends during this period. This study examined the rainfall extremes and trends during the LDS in Nigeria using daily and monthly rainfall data from 19 synoptic stations for the period 1960 to 2020. The Kendal tau correlation, Standardized Precipitation Index (SPI), and descriptive statistics were employed for the study. The result showed the LDS reduction from the western area eastward and northward. The LDS is more intense in August than in July and is characterized by drought, ranging from mild (74.34%) to extreme (2.64%). The droughts fluctuate with wet conditions. The severe and extreme drought was mostly confined to the southwestern area. Lagos observed the highest drought occurrences, 50% of below 10‐mm rainfall and prolonged dry spells. Shaki recorded 13.73% of the total severe droughts while Osogbo recorded 43.33% of extreme drought events. The mean SPI is majorly distributed in space as mild drought and mildly wet respectively, except for a few stations where it ranged from moderate to extreme. A significant trend was negative at Bida ( p ≤ .01), positive at Iseyin ( p ≤ .05), Abeokuta ( p ≤ .01), and Akure ( p ≤ .01) in July, and Bida ( p ≤ .05) in August. The LDS period is associated with hardship through prolonged dry spells and drought. This study explains the extreme rainfall and trends during the LDS to water management and suggests agricultural planning, forecasting, and mitigation of drought impacts.
... The term "dry spell" refers to an extended period of unusually low rainfall and abnormally dry weather conditions, lasting longer than typical but not as severe as a full-fledged drought (Barron et al. 2003;Sawa and Ibrahim 2011;Fall et al. 2021). Dry spells manifest as consecutive days without any precipitation (Breinl et al. 2020). Specifically, a dry spell is officially recognized when there is an absence of rain for three or more days within the wet season (van Fox and Rockström 2003;Traore et al. 2017;Bako et al. 2020). ...
... Specifically, a dry spell is officially recognized when there is an absence of rain for three or more days within the wet season (van Fox and Rockström 2003;Traore et al. 2017;Bako et al. 2020). In addition to limiting soil moisture for millet cultivation, dry spells pose a significant threat to nutrient uptake, thereby having a detrimental impact on millet yields (Paudyal et al. 2016;Breinl et al. 2020). In many instances, the occurrence of dry spells not only reduced millet yields in the region but also led to complete crop loss during the prolonged periods of occurrence, effectively resulting in drought conditions. ...
Climate change has impacted agricultural production systems, especially in the Sahel region, which is fragile climatically, politically, and economically. This region is of particular concern due to its rising population and strategic importance on the African continent. Our review focused on the impact of climate change on millet production in the Central Sahel and aimed to identify adaptation strategies by the farmers. This review shows that increased temperature has a negative impact on millet yield and growth parameters. Other climatic factors significantly affecting millet production in the Central Sahel include drought, desertification, dry spells, rainfall variability, and wind. Projected data suggests a decline in millet production in northern, central, and western Mali by 21%, 20%, and 18%, respectively, by 2030. Additionally, there is an anticipated 17% decrease in pearl millet production in Sub-Saharan Africa by 2050 under future climate change projections. Nevertheless, farmers in the Central Sahel have devised a variety of indigenous climate change adaptation strategies to sustain millet production. These adaptation strategies encompass Zai, half-moon, stone-line, and intercropping. These adaptation practices have proven effective in mitigating the effects of climate change on millet production in the Sahel region. This review suggests strengthening farmers' adaptive capacity to climate change, promoting regional knowledge, integrating millet as a fundamental crop group for food security in the Central Sahel, adopting zero-tillage or minimum-tillage practices during crop production, diversifying crops, and providing heat- and drought-tolerant crop varieties.
Impact of climate variables on millet production