Pub Date : 2024-12-16DOI: 10.1016/j.wace.2024.100740
G.A. Torsah, M.A. Osei, J.N.A. Aryee, J.A.A. Oti, L.K. Amekudzi
Due to their rapidly changing atmospheric processes, forecasting thunderstorms resulting from the merger of isolated cells is a complex task for highly-resolved numerical weather prediction models. This study employed a novel approach to establish the processes that drive updrafts and downdrafts in the merger of isolated thunderstorm cells that produced heavy rainfall and flooding in Kumasi and other parts of the Ashanti Region during June 23–24, 2021. We examine the dynamic and thermodynamic factors to determine the processes that led to the heavy rainfall. The study confirms that the established moisture gradient between the south and north of the region leads to differential surface heating that deepens the planetary boundary layer. Additionally, colder air aloft a warmer surface induces atmospheric overturning, impacts the CAPE and produces substantial updrafts. Also, lower equivalent potential temperature values before storm events, coupled with reduced warming and moisture and increased vertical motion, especially in the mid-levels, favor dry air entrainment, thereby enhancing updraft potential in the mid-troposphere. Besides, the study found that strong rainfall during storms correlates with high soil moisture, evaporative fraction, and variable CAPE and updrafts, which prolonged surface convergence and upper-level divergence, leading to sustained convective activity and heavy rainfall. Notably, the study establishes the roles of African Easterly Waves and low-level wind shear in influencing thunderstorm updrafts and rainfall propagation. Furthermore, we found a single-cell thunderstorm with a variable wind pattern that impacted a defined path during the storm progression. These findings provide valuable information to enhance the development of early warning systems for the detection of localized thunderstorm activities during the monsoon period.
{"title":"Triggers of inland heavy rainfall inducing convective storms in West Africa : Case study of June, 2021","authors":"G.A. Torsah, M.A. Osei, J.N.A. Aryee, J.A.A. Oti, L.K. Amekudzi","doi":"10.1016/j.wace.2024.100740","DOIUrl":"https://doi.org/10.1016/j.wace.2024.100740","url":null,"abstract":"Due to their rapidly changing atmospheric processes, forecasting thunderstorms resulting from the merger of isolated cells is a complex task for highly-resolved numerical weather prediction models. This study employed a novel approach to establish the processes that drive updrafts and downdrafts in the merger of isolated thunderstorm cells that produced heavy rainfall and flooding in Kumasi and other parts of the Ashanti Region during June 23–24, 2021. We examine the dynamic and thermodynamic factors to determine the processes that led to the heavy rainfall. The study confirms that the established moisture gradient between the south and north of the region leads to differential surface heating that deepens the planetary boundary layer. Additionally, colder air aloft a warmer surface induces atmospheric overturning, impacts the CAPE and produces substantial updrafts. Also, lower equivalent potential temperature values before storm events, coupled with reduced warming and moisture and increased vertical motion, especially in the mid-levels, favor dry air entrainment, thereby enhancing updraft potential in the mid-troposphere. Besides, the study found that strong rainfall during storms correlates with high soil moisture, evaporative fraction, and variable CAPE and updrafts, which prolonged surface convergence and upper-level divergence, leading to sustained convective activity and heavy rainfall. Notably, the study establishes the roles of African Easterly Waves and low-level wind shear in influencing thunderstorm updrafts and rainfall propagation. Furthermore, we found a single-cell thunderstorm with a variable wind pattern that impacted a defined path during the storm progression. These findings provide valuable information to enhance the development of early warning systems for the detection of localized thunderstorm activities during the monsoon period.","PeriodicalId":48630,"journal":{"name":"Weather and Climate Extremes","volume":"8 1","pages":""},"PeriodicalIF":8.0,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142874080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-09DOI: 10.1016/j.wace.2024.100741
Sebastian Pfautsch, Agnieszka Wujeska-Klause, Judi R. Walters
Rising summer heat and more frequent and intense heatwaves impact countless metropolitan regions, including Greater Sydney, Australia. An analysis of historic air temperature measurements (1859–2020) reveals a notable increase in the number of ‘hot’ (≥35 °C) days during austral summers. While in the first 120 years of records 351 hot days were identified, 478 hot days were recorded during 2000–2020 alone. Trajectories of summer heat until 2060 indicate that maximum air temperatures in Western Sydney could be ≥ 35 °C during 160 days.
{"title":"Spatiotemporal variation of intra-urban heat and heatwaves across Greater Sydney, Australia","authors":"Sebastian Pfautsch, Agnieszka Wujeska-Klause, Judi R. Walters","doi":"10.1016/j.wace.2024.100741","DOIUrl":"https://doi.org/10.1016/j.wace.2024.100741","url":null,"abstract":"Rising summer heat and more frequent and intense heatwaves impact countless metropolitan regions, including Greater Sydney, Australia. An analysis of historic air temperature measurements (1859–2020) reveals a notable increase in the number of ‘hot’ (≥35 °C) days during austral summers. While in the first 120 years of records 351 hot days were identified, 478 hot days were recorded during 2000–2020 alone. Trajectories of summer heat until 2060 indicate that maximum air temperatures in Western Sydney could be ≥ 35 °C during 160 days.","PeriodicalId":48630,"journal":{"name":"Weather and Climate Extremes","volume":"40 2 1","pages":""},"PeriodicalIF":8.0,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-13DOI: 10.1016/j.wace.2024.100738
Jasmin Heilemann , Christian Klassert , Luis Samaniego , Stephan Thober , Andreas Marx , Friedrich Boeing , Bernd Klauer , Erik Gawel
Extreme weather events are recognized as major drivers of crop yield losses, which threaten food security and farmers’ incomes. Given the increasing frequency and intensity of extreme weather under climate change, it is crucial to quantify the related future yield damages of important crops to inform prospective climate change adaptation planning. In this study, we present a statistical modeling approach to project the changes in crop yields under climate change for eight majorly cultivated field crops in Germany, estimating the impacts of nine types of extreme weather events. To select the most relevant predictors, we apply the least absolute shrinkage and selection operator (LASSO) regression to district-level yield data.
The LASSO models select, on average, 62% of the features, which align with well-known biophysical impacts on crops, suggesting that different extremes at various growth stages are relevant for yield prediction. We project on average 2.5-times more severe impacts on summer crops than on winter crops. Under RCP8.5, crop yields experience a mean change from −2.53% to −8.63% in the far future (2069–98) for summer crops and from −0.80% to −2.88% for winter crops, without accounting for CO2 fertilization effects. Heat impacts are identified as the primary driver of yield losses across all crops for 2069–98, while shifting precipitation patterns exacerbate winter and spring waterlogging, and summer and fall drought.
Our findings underscore the utility of LASSO regression in identifying relevant drivers for projecting changes in crop yields across multiple crops, crucial for guiding agricultural adaptation. While the present analysis can identify empirical relationships, replicating these findings in biophysical models could provide new insights into the underlying processes.
{"title":"Projecting impacts of extreme weather events on crop yields using LASSO regression","authors":"Jasmin Heilemann , Christian Klassert , Luis Samaniego , Stephan Thober , Andreas Marx , Friedrich Boeing , Bernd Klauer , Erik Gawel","doi":"10.1016/j.wace.2024.100738","DOIUrl":"10.1016/j.wace.2024.100738","url":null,"abstract":"<div><div>Extreme weather events are recognized as major drivers of crop yield losses, which threaten food security and farmers’ incomes. Given the increasing frequency and intensity of extreme weather under climate change, it is crucial to quantify the related future yield damages of important crops to inform prospective climate change adaptation planning. In this study, we present a statistical modeling approach to project the changes in crop yields under climate change for eight majorly cultivated field crops in Germany, estimating the impacts of nine types of extreme weather events. To select the most relevant predictors, we apply the least absolute shrinkage and selection operator (LASSO) regression to district-level yield data.</div><div>The LASSO models select, on average, 62% of the features, which align with well-known biophysical impacts on crops, suggesting that different extremes at various growth stages are relevant for yield prediction. We project on average 2.5-times more severe impacts on summer crops than on winter crops. Under RCP8.5, crop yields experience a mean change from −2.53% to −8.63% in the far future (2069–98) for summer crops and from −0.80% to −2.88% for winter crops, without accounting for CO<sub>2</sub> fertilization effects. Heat impacts are identified as the primary driver of yield losses across all crops for 2069–98, while shifting precipitation patterns exacerbate winter and spring waterlogging, and summer and fall drought.</div><div>Our findings underscore the utility of LASSO regression in identifying relevant drivers for projecting changes in crop yields across multiple crops, crucial for guiding agricultural adaptation. While the present analysis can identify empirical relationships, replicating these findings in biophysical models could provide new insights into the underlying processes.</div></div>","PeriodicalId":48630,"journal":{"name":"Weather and Climate Extremes","volume":"46 ","pages":"Article 100738"},"PeriodicalIF":6.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.wace.2024.100739
Shijie Tang , Tianjun Zhou , Lixia Zhang , Liwei Zou , Wenxia Zhang , Shijia Liu
The Taklimakan desert, situated in western China and known for its scarcity of precipitation, experienced an unprecedented precipitation event on 13-14th May 2021. However, the moisture sources and the reason for such extreme precipitation in the heart of the desert remain unexplored. Here, leveraging rain gauge observations from Tazhong Station, situated in the heartland of the Taklimakan Desert, we employed the Flexpart Lagrangian model to examine the moisture source and transport path of this exceptional precipitation event. The target region is situated east of the 500 hPa low trough and to the right of the entrance and left of the exit area of the two upper-level jet streams, providing favorable dynamic conditions for extreme precipitation. Our analysis indicates that the water vapor transport from the eastern boundary of the target area, which originates from the westerly wind along the northern side of the Tianshan Mountains and later turns southward to the Tarim Basin, was the decisive factor for this extreme precipitation event. By employing the Flexpart model, we found that the east particles, which bypassed the Tianshan Mountains and entered the target from its eastern boundary contributed 61.7% of the precipitation, while the west particles contributed only 38.3%. Regarding overall moisture sources, southern Xinjiang emerged as the most significant contributor, accounting for 43.0% of the water vapor, followed by northern Xinjiang at 24.7%, and Central Asia at 21.2%. Our findings suggest that water vapor conditions play a more critical role than dynamic factors in driving such extreme precipitation events in the target area. The water vapor associated with the extreme precipitation event in the target area primarily originates from Southern Xinjiang and its adjacent regions. These results can help us improve the understanding of the mechanism behind extreme precipitation events in arid areas, especially in desert areas.
{"title":"Moisture sources for the unprecedented precipitation event in the heart of Taklimakan desert","authors":"Shijie Tang , Tianjun Zhou , Lixia Zhang , Liwei Zou , Wenxia Zhang , Shijia Liu","doi":"10.1016/j.wace.2024.100739","DOIUrl":"10.1016/j.wace.2024.100739","url":null,"abstract":"<div><div>The Taklimakan desert, situated in western China and known for its scarcity of precipitation, experienced an unprecedented precipitation event on 13-14th May 2021. However, the moisture sources and the reason for such extreme precipitation in the heart of the desert remain unexplored. Here, leveraging rain gauge observations from Tazhong Station, situated in the heartland of the Taklimakan Desert, we employed the Flexpart Lagrangian model to examine the moisture source and transport path of this exceptional precipitation event. The target region is situated east of the 500 hPa low trough and to the right of the entrance and left of the exit area of the two upper-level jet streams, providing favorable dynamic conditions for extreme precipitation. Our analysis indicates that the water vapor transport from the eastern boundary of the target area, which originates from the westerly wind along the northern side of the Tianshan Mountains and later turns southward to the Tarim Basin, was the decisive factor for this extreme precipitation event. By employing the Flexpart model, we found that the east particles, which bypassed the Tianshan Mountains and entered the target from its eastern boundary contributed 61.7% of the precipitation, while the west particles contributed only 38.3%. Regarding overall moisture sources, southern Xinjiang emerged as the most significant contributor, accounting for 43.0% of the water vapor, followed by northern Xinjiang at 24.7%, and Central Asia at 21.2%. Our findings suggest that water vapor conditions play a more critical role than dynamic factors in driving such extreme precipitation events in the target area. The water vapor associated with the extreme precipitation event in the target area primarily originates from Southern Xinjiang and its adjacent regions. These results can help us improve the understanding of the mechanism behind extreme precipitation events in arid areas, especially in desert areas.</div></div>","PeriodicalId":48630,"journal":{"name":"Weather and Climate Extremes","volume":"46 ","pages":"Article 100739"},"PeriodicalIF":6.1,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-07DOI: 10.1016/j.wace.2024.100737
Jun Su , Yihui Ding , Yanju Liu , Jing Wang , Yingxian Zhang
Drought to flood abrupt alternation (DFAA) events, as a special category of compound extreme events that suddenly shift from drought to flood conditions, have significantly greater impacts than individual drought or flood events. In this paper, we have utilized a multifactorial drought index and flood index to identify daily DFAA events occurring in mainland China and in major impact areas during the period 1961–2022. Based on drought and flood index, we have used entropy weighting method to measure the intensity of DFAA events. Our findings indicate that China's DFAA events primarily occur in the hotspots of Huang-Huai-Hai River Basin, the middle and lower Yangtze River Basin, the southeastern coastal area, and the southwestern part of the country. The most frequent and intense DFAA events occur from June to September, with varying subseasonal patterns in the frequency and intensity of events in each hotspot. The frequency of DFAA events in mainland China shows a significant decreasing trend declining at a rate of 0.25 per year in year-round. While DFAA events occurring in the warm season tend to decrease more significantly compared to the year-round at a rate of 0.26 per year. However, the intensity of DFAA events is increasing with a rate of 0.1 per decade in both the year-round and warm season. The evolution of DFAA events and their direct causes varies non-uniformly across regions and months. Subseasonally, frequency and intensity trends diverged monthly across regions, notably with the Huang-Huai-Hai Basin and southeast coast experiencing a July decline in frequency but a surge in intensity. Our research deepens the understanding of changes in DFAA events and provides practical reference for preventing and mitigating drought-to-flood disasters in mainland China.
{"title":"China is suffering from fewer but more severe drought to flood abrupt alternation events","authors":"Jun Su , Yihui Ding , Yanju Liu , Jing Wang , Yingxian Zhang","doi":"10.1016/j.wace.2024.100737","DOIUrl":"10.1016/j.wace.2024.100737","url":null,"abstract":"<div><div>Drought to flood abrupt alternation (DFAA) events, as a special category of compound extreme events that suddenly shift from drought to flood conditions, have significantly greater impacts than individual drought or flood events. In this paper, we have utilized a multifactorial drought index and flood index to identify daily DFAA events occurring in mainland China and in major impact areas during the period 1961–2022. Based on drought and flood index, we have used entropy weighting method to measure the intensity of DFAA events. Our findings indicate that China's DFAA events primarily occur in the hotspots of Huang-Huai-Hai River Basin, the middle and lower Yangtze River Basin, the southeastern coastal area, and the southwestern part of the country. The most frequent and intense DFAA events occur from June to September, with varying subseasonal patterns in the frequency and intensity of events in each hotspot. The frequency of DFAA events in mainland China shows a significant decreasing trend declining at a rate of 0.25 per year in year-round. While DFAA events occurring in the warm season tend to decrease more significantly compared to the year-round at a rate of 0.26 per year. However, the intensity of DFAA events is increasing with a rate of 0.1 per decade in both the year-round and warm season. The evolution of DFAA events and their direct causes varies non-uniformly across regions and months. Subseasonally, frequency and intensity trends diverged monthly across regions, notably with the Huang-Huai-Hai Basin and southeast coast experiencing a July decline in frequency but a surge in intensity. Our research deepens the understanding of changes in DFAA events and provides practical reference for preventing and mitigating drought-to-flood disasters in mainland China.</div></div>","PeriodicalId":48630,"journal":{"name":"Weather and Climate Extremes","volume":"46 ","pages":"Article 100737"},"PeriodicalIF":6.1,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-18DOI: 10.1016/j.wace.2024.100736
Thomas H. Ford
Most droughts go unnamed. At the time they are happening, they are generally referred to simply as “the drought.” After the fact, they are typically designated by a year or run of years rather than by a name: 1927–29, for instance. But in recent decades, proper names have increasingly been bestowed on droughts in southeast Australia in an informal although widely accepted practice. Examples include the Federation Drought, the World War II Drought, the Millennium Drought and, most recently, the Tinderbox Drought. This paper positions the practice of naming droughts within a longer history of naming weather extremes. It examines the implications of the naming practice for the investigation of droughts as complex objects of interdisciplinary knowledge that call for analysis from across the sciences, social sciences and humanities. And it considers the qualities and meanings attributed to the drought of 2017-19 by the name “Tinderbox.” Using the word “tinderbox” to describe environmental conditions has been criticised for naturalizing landscape flammability and so effacing human agency. But in fact the name “Tinderbox Drought” potentially enacts a semantic reversal that allows human-caused climate change to be reassociated discursively with recent and future drought events.
{"title":"Naming droughts: Historical perspectives on the scientific coining of “the Tinderbox Drought”","authors":"Thomas H. Ford","doi":"10.1016/j.wace.2024.100736","DOIUrl":"10.1016/j.wace.2024.100736","url":null,"abstract":"<div><div>Most droughts go unnamed. At the time they are happening, they are generally referred to simply as “the drought.” After the fact, they are typically designated by a year or run of years rather than by a name: 1927–29, for instance. But in recent decades, proper names have increasingly been bestowed on droughts in southeast Australia in an informal although widely accepted practice. Examples include the Federation Drought, the World War II Drought, the Millennium Drought and, most recently, the Tinderbox Drought. This paper positions the practice of naming droughts within a longer history of naming weather extremes. It examines the implications of the naming practice for the investigation of droughts as complex objects of interdisciplinary knowledge that call for analysis from across the sciences, social sciences and humanities. And it considers the qualities and meanings attributed to the drought of 2017-19 by the name “Tinderbox.” Using the word “tinderbox” to describe environmental conditions has been criticised for naturalizing landscape flammability and so effacing human agency. But in fact the name “Tinderbox Drought” potentially enacts a semantic reversal that allows human-caused climate change to be reassociated discursively with recent and future drought events.</div></div>","PeriodicalId":48630,"journal":{"name":"Weather and Climate Extremes","volume":"46 ","pages":"Article 100736"},"PeriodicalIF":6.1,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142526698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-18DOI: 10.1016/j.wace.2024.100735
Selma B. Guerreiro , Stephen Blenkinsop , Elizabeth Lewis , David Pritchard , Amy Green , Hayley J. Fowler
Understanding short-duration intense rainfall is crucial for mitigating flash floods, landslides, soil erosion, and pollution incidents. Yet, most observations from rain gauges are only available at the daily resolution. We use the new Global Sub Daily Rainfall dataset to explore extreme rainfall at both daily and sub-daily durations worldwide. Employing Single Gauge Analysis (SGA) and pioneering global-scale Regional Frequency Analysis (RFA), we reveal for the first time how Generalized Extreme Value Distribution (GEV) parameters change across climates and data durations (1h, 3h, 6h, 24h, and daily). This marks the first-ever near-global-scale RFA, made possible by the development of an algorithm that automates RFA on observed rainfall datasets. We compare our results with GEV applied to a gridded rainfall reanalysis (ERA5). Our key findings are that: 1) using ERA5, return levels are significantly underestimated across all climates for 1h rainfall and across all data durations for gauges in the tropical climate region. Even when accounting for differences between point and areal estimates, the median 1h return level estimates are approximately 40% lower compared to RFA. We therefore strongly advise against the use of reanalysis gridded rainfall for studying these extremes. 2) While most gauges show similar return levels with RFA or SGA, some differ significantly, and either method may yield the highest values. Thus, we strongly recommend using both SGA and RFA simultaneously to estimate return levels for a robust risk assessment in flood infrastructure design. 3) The interaction between daily and sub-daily GEV shape parameters varies across climate regions, rendering a universal method for inferring sub-daily rainfall extremes from daily extremes (e.g., using Intensity-Duration-Frequency curves) impractical. Our research provides innovative methodological insights that warrant consideration in future studies on rainfall extremes. Our results not only benefit local stakeholders globally but also serve as a crucial validation tool for the rising number of convection-permitting climate model experiments conducted worldwide.
{"title":"Unravelling the complex interplay between daily and sub-daily rainfall extremes in different climates","authors":"Selma B. Guerreiro , Stephen Blenkinsop , Elizabeth Lewis , David Pritchard , Amy Green , Hayley J. Fowler","doi":"10.1016/j.wace.2024.100735","DOIUrl":"10.1016/j.wace.2024.100735","url":null,"abstract":"<div><div>Understanding short-duration intense rainfall is crucial for mitigating flash floods, landslides, soil erosion, and pollution incidents. Yet, most observations from rain gauges are only available at the daily resolution. We use the new Global Sub Daily Rainfall dataset to explore extreme rainfall at both daily and sub-daily durations worldwide. Employing Single Gauge Analysis (SGA) and pioneering global-scale Regional Frequency Analysis (RFA), we reveal for the first time how Generalized Extreme Value Distribution (GEV) parameters change across climates and data durations (1h, 3h, 6h, 24h, and daily). This marks the first-ever near-global-scale RFA, made possible by the development of an algorithm that automates RFA on observed rainfall datasets. We compare our results with GEV applied to a gridded rainfall reanalysis (ERA5). Our key findings are that: 1) using ERA5, return levels are significantly underestimated across all climates for 1h rainfall and across all data durations for gauges in the tropical climate region. Even when accounting for differences between point and areal estimates, the median 1h return level estimates are approximately 40% lower compared to RFA. We therefore strongly advise against the use of reanalysis gridded rainfall for studying these extremes. 2) While most gauges show similar return levels with RFA or SGA, some differ significantly, and either method may yield the highest values. Thus, we strongly recommend using both SGA and RFA simultaneously to estimate return levels for a robust risk assessment in flood infrastructure design. 3) The interaction between daily and sub-daily GEV shape parameters varies across climate regions, rendering a universal method for inferring sub-daily rainfall extremes from daily extremes (e.g., using Intensity-Duration-Frequency curves) impractical. Our research provides innovative methodological insights that warrant consideration in future studies on rainfall extremes. Our results not only benefit local stakeholders globally but also serve as a crucial validation tool for the rising number of convection-permitting climate model experiments conducted worldwide.</div></div>","PeriodicalId":48630,"journal":{"name":"Weather and Climate Extremes","volume":"46 ","pages":"Article 100735"},"PeriodicalIF":6.1,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142526697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-17DOI: 10.1016/j.wace.2024.100734
Georgina Falster , Sloan Coats , Nerilie Abram
Australia's Murray-Darling Basin experienced three consecutive years of meteorological drought across 2017–2019, collectively named the ‘Tinderbox Drought’. Rainfall deficits during the three-year drought were most pronounced in the Australian cool season (April to September). Deficits in both the cool season and annual total rainfall were unprecedented in the instrumental record. However, the instrumental record provides just one of a range of equally plausible climate trajectories that could have occurred during this period. To determine if the Tinderbox Drought was outside this range, we used observational data from prior to the onset of the drought to construct Linear Inverse Models (LIMs) that emulate the stationary statistics of Australian rainfall and its connection to global sea surface temperature (SST) anomalies. Overall, we find that rainfall deficits were most unusual in the northern Murray-Darling Basin, and during the final year of the drought. The global SST anomalies observed during the first two years of the Tinderbox Drought, particularly the cool anomalies in the central tropical Pacific and western Indian Ocean, are not typically associated with low rainfall across the Murray-Darling Basin. In terms of single-year rainfall anomalies, the only aspect of the Tinderbox Drought that was beyond the range of the LIMs was annual-total rainfall over the northern Murray-Darling Basin during 2019. This coincided with an extreme positive Indian Ocean Dipole event that was also beyond the range of the LIMs. When considered in terms of basin-wide rainfall over the full three years, rainfall deficits during the Tinderbox Drought were beyond the LIM range in terms of both cool-season and annual-total rainfall. This suggests an anthropogenic contribution to the severity of the drought—likely exacerbated by the 2019 extreme positive Indian Ocean Dipole event.
{"title":"How unusual was Australia's 2017–2019 Tinderbox Drought?","authors":"Georgina Falster , Sloan Coats , Nerilie Abram","doi":"10.1016/j.wace.2024.100734","DOIUrl":"10.1016/j.wace.2024.100734","url":null,"abstract":"<div><div>Australia's Murray-Darling Basin experienced three consecutive years of meteorological drought across 2017–2019, collectively named the ‘Tinderbox Drought’. Rainfall deficits during the three-year drought were most pronounced in the Australian cool season (April to September). Deficits in both the cool season and annual total rainfall were unprecedented in the instrumental record. However, the instrumental record provides just one of a range of equally plausible climate trajectories that could have occurred during this period. To determine if the Tinderbox Drought was outside this range, we used observational data from prior to the onset of the drought to construct Linear Inverse Models (LIMs) that emulate the stationary statistics of Australian rainfall and its connection to global sea surface temperature (SST) anomalies. Overall, we find that rainfall deficits were most unusual in the northern Murray-Darling Basin, and during the final year of the drought. The global SST anomalies observed during the first two years of the Tinderbox Drought, particularly the cool anomalies in the central tropical Pacific and western Indian Ocean, are not typically associated with low rainfall across the Murray-Darling Basin. In terms of single-year rainfall anomalies, the only aspect of the Tinderbox Drought that was beyond the range of the LIMs was annual-total rainfall over the northern Murray-Darling Basin during 2019. This coincided with an extreme positive Indian Ocean Dipole event that was also beyond the range of the LIMs. When considered in terms of basin-wide rainfall over the full three years, rainfall deficits during the Tinderbox Drought were beyond the LIM range in terms of both cool-season and annual-total rainfall. This suggests an anthropogenic contribution to the severity of the drought—likely exacerbated by the 2019 extreme positive Indian Ocean Dipole event.</div></div>","PeriodicalId":48630,"journal":{"name":"Weather and Climate Extremes","volume":"46 ","pages":"Article 100734"},"PeriodicalIF":6.1,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-16DOI: 10.1016/j.wace.2024.100733
Sarah Chapman , Jozef Syktus , Ralph Trancoso , Nathan Toombs , Rohan Eccles
High-resolution climate change projections are required to evaluate local and regional climate change impacts. We used CCAM (Conformal Cubic Atmospheric Model) to dynamically downscale CMIP6 GCMs (Global Climate Models) over Australia under three emissions scenarios, producing a set of 60 simulations at a 10 km resolution. Previous work has evaluated the performance of the downscaled models in the historical period. Here, we evaluate the impact of end-of-century climate change in the downscaled CMIP6-CCAM models for mean and extreme climate under three Shared Socioeconomic Pathways (SSP126, 245 and 370). We find the changes in mean climate are in general similar in the host CMIP6 and downscaled models. For extreme temperature, we find that extreme maximum temperatures (TXx) increase by 3.4 °C, while extreme minimum temperatures (TNn) warm by 3.0 °C. Extreme precipitation generally increases in summer and decreases in winter; however, there is a large amount of inter-model variation in the location and magnitude of change. Consecutive dry days also decrease in most areas in Austral summer and increase in Austral winter. Heatwaves become more frequent and hotter by the end of the century. These results suggest a hotter, wetter Austral summer, with longer, more frequent and more intense heatwaves, and a hotter and drier Austral winter in most areas. This dataset provides useful new high-resolution information on how climate change is likely to impact Australia, which will be a valuable resource to underpin local adaptation responses to future impacts.
{"title":"Projected changes in mean climate and extremes from downscaled high-resolution CMIP6 simulations in Australia","authors":"Sarah Chapman , Jozef Syktus , Ralph Trancoso , Nathan Toombs , Rohan Eccles","doi":"10.1016/j.wace.2024.100733","DOIUrl":"10.1016/j.wace.2024.100733","url":null,"abstract":"<div><div>High-resolution climate change projections are required to evaluate local and regional climate change impacts. We used CCAM (Conformal Cubic Atmospheric Model) to dynamically downscale CMIP6 GCMs (Global Climate Models) over Australia under three emissions scenarios, producing a set of 60 simulations at a 10 km resolution. Previous work has evaluated the performance of the downscaled models in the historical period. Here, we evaluate the impact of end-of-century climate change in the downscaled CMIP6-CCAM models for mean and extreme climate under three Shared Socioeconomic Pathways (SSP126, 245 and 370). We find the changes in mean climate are in general similar in the host CMIP6 and downscaled models. For extreme temperature, we find that extreme maximum temperatures (TXx) increase by 3.4 °C, while extreme minimum temperatures (TNn) warm by 3.0 °C. Extreme precipitation generally increases in summer and decreases in winter; however, there is a large amount of inter-model variation in the location and magnitude of change. Consecutive dry days also decrease in most areas in Austral summer and increase in Austral winter. Heatwaves become more frequent and hotter by the end of the century. These results suggest a hotter, wetter Austral summer, with longer, more frequent and more intense heatwaves, and a hotter and drier Austral winter in most areas. This dataset provides useful new high-resolution information on how climate change is likely to impact Australia, which will be a valuable resource to underpin local adaptation responses to future impacts.</div></div>","PeriodicalId":48630,"journal":{"name":"Weather and Climate Extremes","volume":"46 ","pages":"Article 100733"},"PeriodicalIF":6.1,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142526696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.wace.2024.100728
Alise Babre , Konrāds Popovs , Andis Kalvāns , Marta Jemeļjanova , Aija Dēliņa
In regions where groundwater forms the primary source of drinking water, comprehending the prospective availability of subsurface water resources due to climate change is of paramount importance.
This study evaluates the impact of climate change on groundwater levels in the Baltic States until the end of this century. It employs link between surface and subsurface standardized indices. For forecast it uses various Representative Concentration Pathways (RCP) alongside different Regional Climate Models (RCM).
By linking historical groundwater drought episodes with calculated surface drought indices and accumulation periods observed during defined climate Normals, we project groundwater levels for the short, medium, and long-term future. The study incorporates 13 EURO-CORDEX RCMs under three RCP scenarios.
Our analysis reveals that, compared to the recent climate Normals, an overall increase in groundwater levels is expected at most study sites. However, lower groundwater levels are estimated in the near future. The projected impacts show no significant seasonal bias or spatial conformity. Although these findings are specific to the Baltic region, the methodologies described can be readily adapted for global application.
{"title":"Forecasting the groundwater levels in the Baltic through standardized index analysis","authors":"Alise Babre , Konrāds Popovs , Andis Kalvāns , Marta Jemeļjanova , Aija Dēliņa","doi":"10.1016/j.wace.2024.100728","DOIUrl":"10.1016/j.wace.2024.100728","url":null,"abstract":"<div><div>In regions where groundwater forms the primary source of drinking water, comprehending the prospective availability of subsurface water resources due to climate change is of paramount importance.</div><div>This study evaluates the impact of climate change on groundwater levels in the Baltic States until the end of this century. It employs link between surface and subsurface standardized indices. For forecast it uses various Representative Concentration Pathways (RCP) alongside different Regional Climate Models (RCM).</div><div>By linking historical groundwater drought episodes with calculated surface drought indices and accumulation periods observed during defined climate Normals, we project groundwater levels for the short, medium, and long-term future. The study incorporates 13 EURO-CORDEX RCMs under three RCP scenarios.</div><div>Our analysis reveals that, compared to the recent climate Normals, an overall increase in groundwater levels is expected at most study sites. However, lower groundwater levels are estimated in the near future. The projected impacts show no significant seasonal bias or spatial conformity. Although these findings are specific to the Baltic region, the methodologies described can be readily adapted for global application.</div></div>","PeriodicalId":48630,"journal":{"name":"Weather and Climate Extremes","volume":"46 ","pages":"Article 100728"},"PeriodicalIF":6.1,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142445638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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