Determining optimum tilt angles of solar surfaces in Sakarya,Turkey

Climate change constitutes a major challenge for high productivity in wheat, the most widely grown crop in Germany. Extreme weather events including dry spells and heat waves, which negatively affect wheat yields, are expected to aggravate in the future. It is crucial to improve the understanding of the spatiotemporal development of such extreme weather events and the respective crop-climate relationships in Germany. Thus, the present study is a first attempt to evaluate the historic development of relevant drought and heat-related extreme weather events from 1901 to 2010 on county level (NUTS-3) in Germany. Three simple drought indices and two simple heat stress indices were used in the analysis. A continuous increase in dry spells over time was observed over the investigated periods from 1901–1930, 1931–1960, 1961–1990 to 2001–2010. Short and medium dry spells, i.e., precipitation-free periods longer than 5 and 8 days, respectively, increased more strongly compared to longer dry spells (longer than 11 days). The heat-related stress indices with maximum temperatures above 25 and 28 °C during critical wheat growth phases showed no significant increase over the first three periods but an especially sharp increase in the final 1991–2010 period with the increases being particularly pronounced in parts of Southwestern Germany. Trend analysis over the entire 110-year period using Mann-Kendall test revealed a significant positive trend for all investigated indices except for heat stress above 25 °C during flowering period. The analysis of county-level yield data from 1981 to 2010 revealed declining spatial yield variability and rather constant temporal yield variability over the three investigated (1981–1990, 1991–2000, and 2001–2010) decades. A clear spatial gradient manifested over time with variability in the West being much smaller than in the east of Germany. Correlating yield variability with the previously analyzed extreme weather indices revealed strong spatiotemporal fluctuations in explanatory power of the different indices over all German counties and the three time periods. Over the 30 years, yield deviations were increasingly well correlated with heat and drought-related indices, with the number of days with maximum temperature above 25 °C during anthesis showing a sharp increase in explanatory power over entire Germany in the final 2001–2010 period.     

Climate change,social vulnerability and child nutrition in South Asia

Despite recent advancements in global population well-being and food security, climate change threatens to undermine child nutritional health, particularly for marginalized populations in tropical low- and middle-income countries. South Asia is at particular risk for climate-driven undernutrition due to a combination of historical weather exposures, existing nutritional deficits, and a lack of sanitation access. Previous studies have established that precipitation extremes increase rates of undernutrition in this region, but the existing literature lacks adequate consideration of temperature anomalies, mediating social factors, and the developmentally-relevant timing of exposure. We combine high-resolution temperature and precipitation data with large-sample survey data on household demographics and child anthropometry, using an approach that incorporates three key developmental periods and a rigorous fixed effects design. We find that precipitation extremes in the first year of life significantly decrease children’s height-for-age (HAZ) in South Asia. The detrimental effects of extreme precipitation are especially concentrated in under-resourced households, such as those lacking access to proper sanitation and education for women, while anomalous heat is particularly harmful for children in Pakistan, though it tends to benefit children in some demographic groups. These results indicate that nutritional status in South Asia is highly responsive to climate exposures, and that addressing sanitation infrastructure and other development priorities is a pathway towards reducing this vulnerability.     

Is Strange Weather in the Air? A Study of U.S. National Network News Coverage of Extreme Weather Events

This paper asks whether extreme weather events are becoming more discernible. It uses the Vanderbilt University Television News Archives to determine if annual coverage given to heat waves, droughts, hurricanes and floods has increased on the network news between 1968 and 1996. An index of extreme weather events shows a clear trend toward increased coverage, especially since 1988. However, the different types of extreme events do not receive equal coverage: for example, annual peaks for droughts contain about twice as many stories as the peaks for heat waves. The data further reveal that there is no association between coverage of climate change and the overall coverage of extreme events. While extreme events have attracted more stories in the U.S., there has been no increase in the coverage devoted to extreme events in foreign countries. The possible effects of shifts in TV coverage on the public salience and understanding of climate change are discussed.     

中国极端天气气候研究——“地球系统与全球变化”重点专项项目简介及最新进展

全球变暖背景下,极端天气气候事件频发,并表现出群发性、持续性、复合性等特点,不可预测性增加;持续性强降水、极端低温、复合型极端高温干旱、群发性热浪和台风等极端天气气候事件对我国经济社会和可持续发展影响巨大。然而,上述极端天气气候事件的新特征、关键过程和机理尚不完全清楚,重大极端事件的预报预测水平亟待提升。文章首先简要介绍“地球系统与全球变化”重点专项项目“中国极端天气气候事件的形成机理及其预测和归因”的基本情况。项目拟在分析全球变化背景下对我国造成重大影响的极端天气气候事件新特征的基础上,深入研究多尺度海-陆-气耦合过程影响极端天气气候事件的机理,挖掘极端天气气候事件次季节-季节预测的前兆信号;发展动力与物理统计相结合的极端事件预测新方法,研制针对中国极端事件的新一代高分辨率数值预报与检测归因系统。文章重点总结了自2022年12月项目立项至今取得的最新研究成果和进展。     

Extreme weather events and climate change concern

This paper examines whether experience of extreme weather events—such as excessive heat, droughts, flooding, and hurricanes—increases an individual’s level concern about climate change. We bring together micro-level geospatial data on extreme weather events from NOAA’s Storm Events Database with public opinion data from multiple years of the Cooperative Congressional Election Study to study this question. We find evidence of a modest, but discernible positive relationship between experiencing extreme weather activity and expressions of concern about climate change. However, the effect only materializes for recent extreme weather activity; activity that occurred over longer periods of time does not affect public opinion. These results are generally robust to various measurement strategies and model specifications. Our findings contribute to the public opinion literature on the importance of local environmental conditions on attitude formation.     

Climate Risks and Their Impact on Agriculture and Forests in Switzerland

There is growing evidence that, as a result of global climate change, some of the most severe weather events could become more frequent in Europe over the next 50 to 100 years. The paper aims to (i) describe observed trends and scenarios for summer heat waves, windstorms and heavy precipitation, based on results from simulations with global circulation models, regional climate models, and other downscaling procedures, and (ii) discuss potential impacts on agricultural systems and forests in Switzerland. Trends and scenarios project more frequent heavy precipitation during winter corresponding, for example, to a three-fold increase in the exceedance of today's 15-year extreme values by the end of the 21st century. This increases the risk of large-scale flooding and loss of topsoil due to erosion. In contrast, constraints in agricultural practice due to waterlogged soils may become less in a warmer climate. In summer, the most remarkable trend is a decrease in the frequency of wet days, and shorter return times of heat waves and droughts. This increases the risk of losses of crop yield and forage quality. In forests, the more frequent occurrence of dry years may accelerate the replacement of sensitive tree species and reduce carbon stocks, and the projected slight increase in the frequency of extreme storms by the end of the century could increase the risk of windthrow. Some possible measures to maintain goods and services of agricultural and forest ecosystems are mentioned, but it is suggested that more frequent extremes may have more severe consequences than progressive changes in means. In order to effectively decrease the risk for social and economic impacts, long-term adaptive strategies in agriculture and silviculture, investments for prevention, and new insurance concepts seem necessary.     

Attribution matters: Revisiting the link between extreme weather experience and climate change mitigation responses

The literature suggests that extreme weather experiences have potential to increase climate change engagement by influencing the way people perceive the proximity and implications of climate change. Yet, limited attention has been directed at investigating how individual differences in the subjective interpretation of extreme weather events as indications of climate change moderate the link between extreme weather experiences and climate change attitudes. This article contends that subjective attribution of extreme weather events to climate change is a necessary condition for extreme weather experiences to be translated into climate change mitigation responses, and that subjective attribution of extreme weather to climate change is influenced by the psychological and social contexts in which individuals appraise their experiences with extreme weather. Using survey data gathered in the aftermath of severe flooding across the UK in winter 2013/2014, personal experience of this flooding event is shown to only directly predict perceived threat from climate change, and indirectly predict climate change mitigation responses, among individuals who subjectively attributed the floods to climate change. Additionally, subjective attribution of the floods to climate change is significantly predicted by pre-existing climate change belief, political affiliation and perceived normative cues. Attempts to harness extreme weather experiences as a route to engaging the public must be attentive to the heterogeneity of opinion on the attributability of extreme weather events to climate change.     

黔东南地区各季节极端干期日数的时空分布特征

利用1961—2009年黔东南地区16个地面气象站的逐日降水资料,分别统计了四季最大连续无雨日数(日降水量<0.1mm)的时间序列,采用正交函数分解、Mann-Kendall突变检验和线性倾向估计等方法,分析了各季节极端干期日数的空间结构和时间演变规律。结果表明,黔东南地区各季节极端干期日数的时空分布存在较大差异,极端干期日数最多出现在秋季,最少是春季;夏季黔东南北部的极端干期日数多,春、秋季南部多,冬季南、北部多,西部四季相对较少,年内非均匀性特征显著。在大尺度天气系统控制下,四季极端干期日数事件的步调基本一致,黔东南中东部发生异常的频次较高,不同季节的天气系统对黔东南各区域的影响具有明显的局地性和阶段性;近49年中各季节出现极端干期日数典型多的年份比典型少的年份多;进入21世纪以后,春、秋、冬季极端干期日数均呈显著的增多趋势,而夏季变化的特征不明显。     

Contributors to the frequency of intense climate disasters in Asia-Pacific countries

With record breaking heat waves, dryness, and floods in several parts of the world in recent years the question arises whether and to what extent the hazard of hydrometeorological extreme weather events has changed, and if changes can be attributed to specific causes. The methodology of probabilistic event attribution allows to evaluate such potential changes in the occurence probabilities of particular types of extreme events. We show that such a probabilistic assessment not only provides information on changing hazards in hydrometerological events but also permits statements about multivariate combinations of hydrometeorological variables. Hence attribution studies could be targeted specifically towards relevant impacts in particular sectors, if different suitable multivariate proxies are used. We demonstrate our methodology by using combinations of temperature, precipitation and humidity in the large ensemble of climate simulations within the weather@home project in order to derive impact-relevant quantities such as a seasonal water balance and heat stress imposed on the human body. Finally, we estimate the hazard probabilities of those events in South-East Europe, a region that has recently experienced severe summer dryness (2012) in combination with multiple heat waves.     

湖南极端干旱气候时段人影作业潜力分析

利用湖南97个气象观测站逐日综合气象干旱指数、逐日降水量和湖南天气气候分区,研究湖南极端干旱特征和极端干旱时段内人工影响天气增雨潜力,结果表明:①湖南极端干旱期有相当的增雨潜力,各个分区的极端干旱频次和大气可降水量年代际变化除70年代外均呈现为北少南多的特点。②极端干旱时段内各分区年均可增雨日数主要表现为月际差异,可增雨日数主要集中在8—10月,各分区区域差异较小,各分区在伏旱期的可增雨日数大约占伏旱期的16%～20%。③湖南极端干旱按照出现的季节分类有11种,频次最高的是夏秋连旱,同时夏秋连旱的可增雨日数最多。     

Impacts of Multi-Scale Solar Activity on Climate. Part I: Atmospheric Circulation Patterns and Climate Extremes

The impacts of solar activity on climate are explored in this two-part study.Based on the principles of atmospheric dynamics,Part I propose an amplifying mechanism of solar impacts on winter climate extremes through changing the atmospheric circulation patterns.This mechanism is supported by data analysis of the sunspot number up to the predicted Solar Cycle 24,the historical surface temperature data,and atmospheric variables of NCEP/NCAR Reanalysis up to the February 2011 for the Northern Hemisphere winters.For low solar activity,the thermal contrast between the low-and high-latitudes is enhanced,so as the mid-latitude baroclinic ultra-long wave activity.The land-ocean thermal contrast is also enhanced,which amplifies the topographic waves.The enhanced mid-latitude waves in turn enhance the meridional heat transport from the low to high latitudes,making the atmospheric "heat engine" more efficient than normal.The jets shift southward and the polar vortex is weakened.The Northern Annular Mode(NAM) index tends to be negative.The mid-latitude surface exhibits large-scale convergence and updrafts,which favor extreme weather/climate events to occur.The thermally driven Siberian high is enhanced,which enhances the East Asian winter monsoon(EAWM).For high solar activity,the mid-latitude circulation patterns are less wavy with less meridional transport.The NAM tends to be positive,and the Siberian high and the EAWM tend to be weaker than normal.Thus the extreme weather/climate events for high solar activity occur in different regions with different severity from those for low solar activity.The solar influence on the midto high-latitude surface temperature and circulations can stand out after removing the influence from the El Nin o-Southern Oscillation.The atmospheric amplifying mechanism indicates that the solar impacts on climate should not be simply estimated by the magnitude of the change in the solar radiation over solar cycles when it is compared with other external radiative forcings that do not influence the climate in the same way as the sun does.     

Environmental stress and agricultural landownership in Africa

We examine how weather variability affects agricultural landownership rates in Africa, where at least half of the population depends on agriculture to earn a livelihood. In the absence of effective adaptation strategies, households that experience difficulties farming due to environmental stress might leave their land. With implications for demography – through migration – and political instability – when affected populations express grievances – changing landownership patterns could make existing development challenges on the continent even more difficult. We test our hypothesis that drier than average growing seasons will reduce landownership rates using Demographic and Health Surveys (DHS). Our DHS dataset includes interviews with 850,961 households in 35 African countries between 2005 and 2017. Compared to regions experiencing weather near the historical average, those with five consecutive dry growing seasons before the DHS experienced a 6.93% decline in the landownership rate. For every additional dry growing season during the five years before each survey, the landownership rate fell by 1.38%. A host of robustness checks support our general conclusion that drying conditions are associated with lower landownership rates.     

驻马店极端气温分析

利用驻马店10个站气象资料，分析了极端温度的时间变化特征、高温天气与6--8月降水量之间的关系和极端睛热高温、极端湿热高温天气形成的天气背景及影响因子，确定了高温出现的前期预报指标。     

Heat vulnerability and adaptation of low-income households in Germany

Heat waves associated with global warming are a significant hazard to human health, and they particularly endanger low-income households. In this study, we systematically analyze how the different components of heat vulnerability are related to household income, and present empirical evidence on the determinants of heat adaptation, focusing on the role of income. We contribute the first empirical analysis of heat vulnerability using household-level data at the national level, based on a longitudinal survey, including data points for 10,226 households in Germany in the period 2012–2020. Our results indicate that low income households are significantly more heat sensitive and have lower adaptive capacity than high income households, measured inter alia by health status, household composition, and economic and psychological resources to implement adaptation measures. However, heat hazard and exposure levels are comparable between income groups, hence there is no sorting of richer households into less hazardous or exposed locations on a national scale. We also contribute robust empirical evidence on the factors influencing household decisions to implement technical adaptation measures (e.g. installation of air conditioning), ultimately showing that the adaptation behavior of the most vulnerable households (e.g. people with poor health conditions or the elderly) is not limited by financial constraints.     

江西早稻高温热害发生时间分布特征

以江西早稻为例,利用1981—2016年气象资料、早稻高温热害灾情史料和生育期资料,构建历史早稻高温热害样本集合,在Kolmogorov-Smirnov（K-S）分布拟合检验的基础上,采用信息扩散方法计算得到早稻高温热害总样本和不同持续日数（3~5 d,6~8 d和8 d以上）不同等级（轻度、中度、重度）热害在早稻抽穗期前后的发生概率。结果表明:早稻高温热害起始于抽穗前6 d至抽穗后20 d,抽穗扬花期发生概率最高,随着早稻进入乳熟期高温热害发生概率逐渐降低。早稻抽穗扬花期持续3~5 d早稻高温热害以轻度、中度为主,5 d以上中度、重度高温热害发生概率为98.77%;随着早稻进入乳熟期,高温热害以中度和轻度为主,重度高温热害概率显著降低。早稻轻度高温热害的主要致灾时段为抽穗至灌浆中期,中度高温热害的主要致灾时段为抽穗至灌浆中前期,而重度高温热害的主要致灾时段为孕穗期至灌浆初期。     

西安市霾天气与清洁天气变化特征及影响因素分析

利用2006-2012年西安市污染物质量浓度、气象站逐时地面风场、相对湿度和能见度等资料,依据霾天气的定义统计理论霾日数,对比人工观测霾日与判据统计理论霾日的合理性,通过对霾天气与清洁天气过程的气象条件分析,分析西安市霾天气与清洁天气过程的变化特征及影响因素。结果表明：2006-2012年西安市霾天气过程在干季发生频率较高,湿季发生较少。地面风场对霾天气过程影响较大,绝大部分霾天气过程的日平均风速＜1.5 m·s^-1;干季大部分霾天气过程日平均风速≤1.0 m·s^-1,极端个例甚至在0.5 m·s^-1以下。清洁天气过程在干季发生次数多于湿季,主要与干季风速较大和湿度较小相关。     

Projected Changes in Extreme High Temperature and Heat Stress in China

High temperature accompanied with high humidity may result in unbearable and oppressive weather. In this study, future changes of extreme high temperature and heat stress in mainland China are examined based on daily maximum temperature (T_x) and daily maximum wet-bulb globe temperature (T_w). T_w has integrated the effects of both temperature and humidity. Future climate projections are derived from the bias-corrected climate data of five general circulation models under the Representative Concentration Pathways (RCPs) 2.6 and 8.5 scenarios. Changes of hot days and heat waves in July and August in the future (particularly for 2020–50 and 2070–99), relative to the baseline period (1981–2010), are estimated and analyzed. The results show that the future T_x and T_w of entire China will increase by 1.5–5°C on average around 2085 under different RCPs. Future increases in T_x and T_w exhibit high spatial heterogeneity, ranging from 1.2 to 6°C across different regions and RCPs. By around 2085, the mean duration of heat waves will increase by 5 days per annum under RCP8.5. According to T_x, heat waves will mostly occur in Northwest and Southeast China, whereas based on T_w estimates, heat waves will mostly occur over Southeast China and the mean heat wave duration will be much longer than those from T_x. The total extreme hot days (T_x or T_w > 35°C) will increase by 10–30 days. Southeast China will experience the severest heat stress in the near future as extreme high temperature and heat waves will occur more often in this region, which is particularly true when heat waves are assessed based on T_w. In comparison to those purely temperature-based indices, the index T_w provides a new perspective for heat stress assessment in China.     

全球变暖与城市效应共同作用下的极端天气气候事件变化的最新认知

近年来,城市气候变化问题引起高度关注.综合IPCC第一工作组第六次评估报告(IPCC AR6)关于气候变暖背景下城市对极端天气气候事件影响的评估,本文得到以下科学认识:城市化加剧了局部气候变暖,全球许多城市都面临更多更强的高温热浪事件;城市化使得诸多城市区域及其下风向极端降水增加,地表径流加强;沿海城市受到日益加剧的与...     

武汉市10个主要极端天气气候指数变化趋势分析

根据武汉市1951—2007年逐日气温、降水量计算分析了10个极端天气气候指数的变化特征。结果表明:1)4个气温指数中,年及四季高、低温阈值均为上升趋势,并造成最长热浪天数的延长和霜冻日数的减少;低温阈值升速明显快于高温阈值,高温阈值仅在春季变化显著,最长热浪天数仅在冬季变化显著;低温阈值则为极显著上升趋势,尤其是年和冬季,造成"热春"、"暖冬"频繁;暖夜、闷热、傍晚至夜间的强对流等显著增多,暖日、高温热浪增加,霜冻日大幅减少。2)6个极端降水指数以增趋势为主,其中强降水阈值、比例、日数以及最大5日降水量在冬季增趋势最明显,仅夏季强降水阈值、比例略有减小,冬季日降水强度的增大趋势、夏季持续干期的缩短趋势显著性水平分别可达0.1、0.01。3)一些气温指数在1980—1990年代发生突变,而降水指数未现突变。     

高温热浪指标研究

根据热浪所具有的气温异常偏高(或为高温闷热)及通常要持续一段时间这两个特征,研究设计了综合表征炎热程度和过程累积效应的热浪指数作为热浪的判别指标,并提出了热浪的分级标准.利用1994和1995年7-8月武汉市逐日中暑人数和2003年7 8月上海市逐日死亡人数资料对热浪指标和分级标准进行了验证分析,结果表明,热浪指数可以...