Weather and Climate Extremes最新文献_第2页

Projected changes in daily temperature extremes for selected locations over South Africa

IF 6.1 1区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Weather and Climate Extremes

Pub Date : 2025-02-13 DOI: 10.1016/j.wace.2025.100753

Charlotte M. McBride , Andries C. Kruger , Charmaine Johnston , Liesl Dyson

Extreme events, particularly very high temperatures, are expected to increase because of climate change. It is thus essential that localised studies be done to quantify the magnitude of potential changes so that proper planning, especially effective adaptation measures, can be affected. This study analysed annual extreme daily maximum temperatures for future climate change scenarios at 22 locations in South Africa, through analysis of a subset of the Coordinated Regional Downscaling Experiment (CORDEX) model ensemble datasets. The multi-model simulations were validated against observational data obtained from the South African Weather Service for the period 1976–2005. Two study periods of mid- (2036–2065) and far-future (2066–2095) were analysed for two Representative Concentration Pathways, i.e., RCP4.5 and RCP8.5. Bias correction was done on the model data to correct simulated historical climate data, to be more characteristic of observed measurements. While the method included adjustment for variance, systematic underestimations of extremes were still evident. The Generalized Extreme Value distributions were fitted to the bias-corrected projections, and 10-, 50- to 100-year return periods quantile values were estimated. The return period quantile values are likely to increase under both Representative Concentration Pathways in the mid- and far-future periods, with the largest increase in return period quantile values set to occur towards the end of the century under the highest emission scenario. All stations showed an increase in the frequency of days with maximum temperatures above specific critical thresholds, with some stations under the RCP8.5 scenario projected to experience temperatures of greater than 32°C (35°C) for more than 200 (100) days per year by the end of the century, an increase from a baseline of approximately 70 to 150 (14 to 83). For the same scenario, Return periods for 38°C for most stations are projected to be shorter than a year. From the above and considering the likely underestimation in the severity of the projected changes, i.e. too low return period quantile values, the general implication is a strong likelihood that most places in South Africa is likely to experience a strong increase in the intensity, duration, and frequency of very hot extremes in future, with potentially dire consequences to relevant socio-economic sectors. We suggest that future research, comprised of the full set of CORDEX data be conducted to optimise the results of this study.

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引用次数: 0

Distinctive local and large-scale processes associated with daytime, nighttime and compound heatwaves in China

IF 6.1 1区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Weather and Climate Extremes

Pub Date : 2025-02-12 DOI: 10.1016/j.wace.2025.100749

Yanheng Luo , Song Yang , Tuantuan Zhang , Yueyue Yu , Ming Luo , Lianlian Xu

Different heatwave types exert distinctive impacts on the socio-economic and ecosystems, but the potential mechanisms for different heatwave types remain poorly understood. In this study, we identify the hot spots of daytime, nighttime, and compound heatwaves over China during 1991–2022, and provide a systematic investigation of their distinctive atmospheric configurations. The results show that the daytime heatwave clusters in China are closely linked to the various teleconnection wave trains (i.e., Eurasian or Scandinavian patterns) with quasi-barotropic structures. The hot spots are typically located at the center or southern flank of the anticyclone in the troposphere, accompanied by anomalous descending motions and reduced cloud cover, thus providing dry-hot conditions for daytime heatwaves. In comparison, the nighttime heatwave clusters are modulated by the atmospheric circulations that exhibit more local features, and the hot spots are generally located between the anticyclone and the cyclone with anomalous ascending motions. This feature favors the convergence of water vapor and leads to more cloudy and moist conditions, which hinder upward emissions of longwave radiation at night. On the other hand, the hot spots of compound heatwave clusters are controlled by the anticyclone in the middle level while they are located between the anticyclone and the cyclone in the lower level, which can simultaneously cause adiabatic descending motions and enhanced water vapor, conducive to the continuation of high temperature from daytime to nighttime.

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引用次数: 0

Dynamical downscaling projections of mean and extreme climate over the Tibetan Plateau under 2 SSP scenarios

IF 6.1 1区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Weather and Climate Extremes

Pub Date : 2025-02-12 DOI: 10.1016/j.wace.2025.100747

Jiewei Zhou , Jianbin Huang , Yao Yao , Yong Luo

The Tibetan Plateau (TP) has consistently garnered attention due to its sensitivity to global climate change and the implications of future global warming. This study employs the Weather Research and Forecasting (WRF) model, driven by three global models from the Sixth Coupled Model Intercomparison Project (CMIP6), to investigate future mean and extreme climate changes over the TP. WRF's historical simulation (1995–2014) more accurately reproduces the spatial distribution of temperature, precipitation, and climate extremes compared to global models. Projections suggest that by mid-21st century, under SSP1-2.6 and SSP5-8.5, the TP's average temperature will rise by 1.27 °C and 1.91 °C, respectively, with autumn experiencing the most warming. The western plateau is expected to warm more than the eastern part. Precipitation over the TP is expected to increase, especially in the northwest and central-east regions, by 5%–10%, with winter precipitation increasing by more than 10% under the SSP5-8.5 scenario. Extreme high-temperature events are projected to increase in frequency and intensity, while extreme low-temperature events are expected to decrease and weaken. The intensity and frequency of extreme heavy precipitation events are also expected to rise, mainly in the western and southeastern plateau. Drought events are projected to become less severe in north TP, especially in the Qaidam Basin. The differences between WRF simulations and global models in seasonal and scenario-dependent changes underscore that regional models capture finer regional climate details and reveal limitations in global models. Hence, it is crucial to consider these differences when assessing climate impacts and developing adaptation strategies.

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引用次数: 0

Representation of extreme El Niño events and associated atmospheric moisture flux divergence in the central-eastern tropical Pacific in a CMIP6 model ensemble CMIP6 模型集合中极端厄尔尼诺事件和热带太平洋中东部相关大气水汽通量分异的表征

IF 6.1 1区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Weather and Climate Extremes

Pub Date : 2025-02-08 DOI: 10.1016/j.wace.2025.100746

Janeet Sanabria , Raphael Neukom , Alan Llacza , Nadine Salzmann , Pierluigi Calanca

Extreme El Niño events entail important socio-economic challenges, both in regions such as South America directly affected by their impacts and in regions around the world that are influenced by the associated teleconnections. Uncertainty remains about the ability of recent climate models to reproduce the characteristics and impacts of extreme El Niño events. In this study, we evaluate the ability of 32 CMIP6 models to simulate extreme El Niño events, focusing on their occurrence, their seasonal evolution, and the characteristics of the associated atmospheric moisture flux divergence. Our results reveal the reasonable performance of the CMIP6 ensemble in reproducing the observed anomalies and seasonal cycles of extreme El Niño events. The ensemble mean also captures the average temporal evolution and magnitudes of moisture flux anomalies, but fails to reproduce some important aspects of the associated spatial patterns. Most individual models have marked deficiencies in adequately simulating the seasonal cycle of atmospheric moisture flux divergence dynamics and reproducing a clear distinction between moderate and extreme events. The latter indicates that the atmospheric–ocean coupling and resulting precipitation anomaly patterns over Ecuador and northern Peru are still not correctly reproduced by the individual models. These deficiencies echo previous studies and underscore the limitations of current global climate models in providing reliable insights into the impacts of climate change on El Niño extremes and their consequences for regional atmospheric dynamics and precipitation. This work highlights the need for further research to improve model representations of extreme El Niño events and their associated impacts on vulnerable regions, thereby facilitating more effective risk management and adaptation measures.

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引用次数: 0

Human-induced climate change increased 2021–2022 drought severity in horn of Africa

IF 6.1 1区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Weather and Climate Extremes

Pub Date : 2025-02-06 DOI: 10.1016/j.wace.2025.100745

Joyce Kimutai , Clair Barnes , Mariam Zachariah , Sjoukje Y. Philip , Sarah F. Kew , Izidine Pinto , Piotr Wolski , Gerbrand Koren , Gabriel Vecchi , Wenchang Yang , Sihan Li , Maja Vahlberg , Roop Singh , Dorothy Heinrich , Julie Arrighi , Carolina Pereira Marghidan , Lisa Thalheimer , Cheikh Kane , Emmanuel Raju , Friederike E.L. Otto

From October 2020 to early 2023, Eastern Africa experienced five consecutive failed (SPEI -2.6) rainy seasons, resulting in the worst drought in 40 years. This led to harvest failures, livestock losses, water scarcity, and conflicts, leaving approximately 4.35 million people in need of humanitarian aid. To understand the role of human-induced climate change in the drought, we analysed rainfall trends and the combined effect of rainfall deficit with high temperatures in the Southern Horn of Africa covering parts of southern Ethiopia, southern Somalia, and eastern Kenya. We employed various climate models and observations to assess changes in 24-month rainfall (2021–2022), and seasonal rainfall; both the (March-April-May, MAM) ‘long rains’ and (October-November-December, OND) ‘short rains’ in 2022. We also contextualised the event in terms of vulnerability and exposure to understand how these elements influenced the magnitude of the impacts. Our analysis shows that anthropogenic influence on the combined effects of low rainfall and high evapotranspiration caused by higher temperatures made the drought exceptional, leading to major crop and pasture losses and water shortages. Our results also show a decline in rainfall during MAM and an upward trend during OND, which is attributable to climate change. Despite the wetting trend in OND season, the drought years concluded with successive La Niña conditions, typically linked with below-average rainfall in the region during that season. We do not find a trend in the 24-month precipitation. The assessment on vulnerability and exposure highlights the need for enhanced preparedness of government drought management systems and international aid infrastructure for future severe and prolonged droughts. The study's findings, combined with climate projections that indicate increased heavy precipitation in the region, underscore the pressing necessity for robust adaptation strategies that can address both wet and dry extremes. The impacts of climate change in Eastern Africa necessitate investments in adaptive measures and resilience building that can evolve with emerging climate signals.

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引用次数: 0

Simulation of an intense tropical cyclone in the conformal cubic atmospheric model and its sensitivity to horizontal resolution

IF 6.1 1区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Weather and Climate Extremes

Pub Date : 2025-02-01 DOI: 10.1016/j.wace.2025.100744

Son C. H. Truong, Hamish A. Ramsay, Tony Rafter, Marcus J. Thatcher

In this study, we evaluated the Conformal Cubic Atmospheric Model's (CCAM) ability to simulate the characteristics of severe Tropical Cyclone (TC) Hina, which occurred in the Southwest Pacific in 1985. We compared the model's performance using both a quasi-uniform grid and a variable-resolution grid to investigate differences in the representation of TC Hina's properties, such as tracks and intensity. We further examined the impact of horizontal resolutions (50 km, 25 km, and 12.5 km) on the wind structure, surface fluxes, and precipitation. Our findings indicate that CCAM reasonably reproduces the TC Hina's track, aligning with IBTrACS and ERA5 data. Higher resolutions in both quasi-uniform and variable resolution configurations result in improved representation of Hina's intensity, with the 12.5 km resolution showing the best performance. Both grid configurations show similar time series of maximum wind speed (V_max) and minimum sea level pressure (SLP_min). The model is able to accurately represent a range of synoptic meteorological phenomena surrounding the TC centre, as well as the moisture sources feeding into the inner-core of the TC at higher resolutions. Furthermore, we find that the simulated structures of the TC, including primary and secondary circulations, surface fluxes, and precipitation are strongly influenced by horizontal resolution. Our findings suggest that higher resolutions promote greater precipitation and larger latent heat fluxes near the TC centre (facilitating TC intensification). While challenges remain in simulating TCs over the entire Australasian CORDEX domain, the study demonstrates CCAM's capability to simulate intense TCs at high resolution. These findings provide valuable insights into the understanding of how CCAM can be effectively utilised for regional climate projections of TCs.

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引用次数: 0

Data-driven upper bounds and event attribution for unprecedented heatwaves

IF 6.1 1区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Weather and Climate Extremes

Pub Date : 2025-01-30 DOI: 10.1016/j.wace.2025.100743

Mark D. Risser , Likun Zhang , Michael F. Wehner

The last decade has seen numerous record-shattering heatwaves in all corners of the globe. In the aftermath of these devastating events, there is interest in identifying worst-case thresholds or upper bounds that quantify just how hot temperatures can become. Generalized Extreme Value theory provides a data-driven estimate of extreme thresholds; however, upper bounds may be exceeded by future events, which undermines attribution and planning for heatwave impacts. Here, we show how the occurrence and relative probability of observed yet unprecedented events that exceed a priori upper bound estimates, so-called “impossible” temperatures, has changed over time. We find that many unprecedented events are actually within data-driven upper bounds, but only when using modern spatial statistical methods. Furthermore, there are clear connections between anthropogenic forcing and the “impossibility” of the most extreme temperatures. Robust understanding of heatwave thresholds provides critical information about future record-breaking events and how their extremity relates to historical measurements.

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引用次数: 0

Characteristics of precipitation associated with post-tropical cyclones in the North Atlantic 北大西洋后热带气旋降水特征

IF 6.1 1区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Weather and Climate Extremes

Pub Date : 2024-12-21 DOI: 10.1016/j.wace.2024.100742

Haider Ali , Leonard Chek Yuet Wong , Andreas F. Prein , Hayley J. Fowler

Precipitation brought by cyclone systems has long been known as a major contributor to devastating flood events.Recent post-tropical cyclones (PTCs), which transform from tropical cyclones (TC) to extratropical cyclones (ETC) in the mid-latitudes, are among the strongest cyclones in the mid-latitude European region. Understanding PTCs and their precipitation behavior, particularly in the context of recent observations, is crucial for assessing and mitigating hazards effectively. Here, we couple precipitation data and best track data to examine different aspects of PTCs, such as track characteristics and the associated precipitation behavior. Using the International Best Track Archive for Climate Stewardship (IBTrACS) data from 2001 to 2020, we find that TCs and ETCs peak during fall months, especially in October, with cyclogenesis and extratropical transition (ET) locations varying seasonally. ETCs share characteristics with frontal cyclones, such as faster translation velocities and larger radii than TCs. Hourly precipitation data from Integrated Multi-satellitE Retrievals for Global precipitation measurement (IMERG) (2001–2020) shows lower intensity during ETC phases compared to TC phases but with broader areal coverage – precipitation shields -, with ETCs consistently producing more total rainfall over 24 h. The centroid of precipitation regions during ETC phases shifts northeast of the cyclone centers for short-duration rainfall and west-southwest for longer durations, indicating widespread precipitation further from the cyclone centre. We found asymmetric precipitation distributions favoring the left side of the cyclone track during ETC phases, especially for lower-intensity events. Our results provide valuable insights into the evolving nature of PTCs, and their impact on precipitation patterns, which are crucial for hazard assessment models and mitigation strategies to safeguard communities and minimize the risks associated with these potential hazards.

长期以来，气旋系统带来的降水一直被认为是造成毁灭性洪水事件的主要原因。近代后热带气旋（ptc）是中纬度地区由热带气旋（TC）转变为温带气旋（ETC）的气旋，是欧洲中纬度地区最强的气旋之一。了解ptc及其降水行为，特别是在最近观测的背景下，对于有效评估和减轻危害至关重要。在这里，我们将降水数据和最佳路径数据结合起来，研究ptc的不同方面，如路径特征和相关的降水行为。利用国际气候管理最佳跟踪档案（IBTrACS） 2001 - 2020年的数据，我们发现TCs和ETCs在秋季达到峰值，特别是在10月，并且气旋发生和温带过渡（ET）的位置随季节而变化。ETCs与锋面气旋具有相同的特征，例如比tc更快的平移速度和更大的半径。来自全球降水测量综合多卫星检索（IMERG）（2001-2020）的每小时降水数据显示，ETC阶段的强度低于TC阶段，但面积覆盖范围更广——降水屏蔽——在24小时内，ETC阶段降水区域的质心在短时间内向东北移动，在较长时间内向西南偏西移动。表明离气旋中心更远的地方有广泛的降水。我们发现ETC阶段的降水分布不对称，特别是在低强度事件中，降水分布偏向气旋路径的左侧。我们的研究结果为ptc的演变性质及其对降水模式的影响提供了有价值的见解，这对于危害评估模型和缓解策略至关重要，以保护社区并最大限度地减少与这些潜在危害相关的风险。

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引用次数: 0

Triggers of inland heavy rainfall inducing convective storms in West Africa : Case study of June, 2021 西非内陆强降雨诱发对流风暴的触发因素：以2021年6月为例

IF 6.1 1区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Weather and Climate Extremes

Pub Date : 2024-12-16 DOI: 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.

由于其快速变化的大气过程，对高分辨率数值天气预报模式来说，预报由孤立单体合并引起的雷暴是一项复杂的任务。本研究采用了一种新颖的方法来建立在2021年6月23日至24日期间在库马西和阿散蒂地区其他地区产生强降雨和洪水的孤立雷暴单体合并过程中驱动上升和下降气流的过程。我们研究了动力和热力学因素，以确定导致强降雨的过程。该研究证实，该地区南北之间已建立的水汽梯度导致了不同的地表加热，从而加深了行星边界层。此外，较冷的空气在较暖的表面上方引起大气翻转，影响CAPE并产生大量上升气流。此外，风暴事件前较低的等效位温值，加上暖湿减少和垂直运动增加，特别是在中层，有利于干燥空气夹带，从而增强对流层中层的上升气流潜力。此外，研究发现，暴雨期间强降雨与土壤湿度、蒸发分数高、CAPE和上升气流变化有关，这些变化延长了地面辐合和高层辐散时间，导致持续对流活动和强降雨。值得注意的是，该研究确定了非洲东风波和低层风切变在影响雷暴上升气流和降雨传播中的作用。此外，我们还发现了一个具有可变风型的单细胞雷暴，它在风暴发展过程中影响了一条确定的路径。这些发现提供了宝贵的资料，有助发展侦测季风期局部雷暴活动的早期预警系统。

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引用次数: 0

Spatiotemporal variation of intra-urban heat and heatwaves across Greater Sydney, Australia 澳大利亚大悉尼地区城市内热量和热浪的时空变化

IF 6.1 1区地球科学 Q1 METEOROLOGY & ATMOSPHERIC SCIENCES

Weather and Climate Extremes

Pub Date : 2024-12-09 DOI: 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.

A second, more granular analysis compared air temperature measurements recorded at 274 urban microsites during the summers of 2019 and 2020 with measurements of official weather stations in Central and Western Sydney. Results revealed that the number of hot (≥35 °C), extreme (≥40 °C), and ‘catastrophic’ (≥45 °C) heat days was markedly greater than those reported by official weather stations. Underreporting of heat was greatest across the Local Government Area (LGA) of Cumberland, where data loggers recorded 32 hot and 15 extreme heat days, compared to 7 hot and 1 extreme heat day recorded by the nearest official station. Based on empirical measurements, a set of novel ‘heat risk’ maps identify suburbs and regions inside LGAs where underreporting of summer heat is high. Findings indicate that communities across Greater Sydney are exposed to more frequent and more intense heat than previously reported. Underreporting of local urban heat results in lower preparedness and thus higher risk of harm to urban populations of Greater Sydney and likely many other metropolitan regions.

不断上升的夏季炎热和更频繁、更强烈的热浪影响着包括澳大利亚大悉尼在内的无数大都市地区。对历史气温测量（1859-2020）的分析显示，在南方夏季，“热”（≥35°C）天数显著增加。在有记录的前120年中，确定了351个高温天，仅2000-2020年就记录了478个高温天。到2060年的夏季高温轨迹表明，在160天内，西悉尼的最高气温可能≥35°C。

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引用次数: 0