SGER: Investigating the Joint Occurrence of Summer Drought and Heat Waves in Climate Change Projections

SGER：调查气候变化预测中夏季干旱和热浪的共同发生

• 批准号: 0739256
• 负责人: Bradfield Lyon
• 金额: --
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-15 至 2009-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0739256&HistoricalAwards=false
• 关键词: SGER; Investigating; Joint; Occurrence; Summer

This is a grant under a Climate Variability and Predictability (CLIVAR) Program pilot project called DRICOMP, for the Drought in Coupled Models Project, which focuses on making initial explorations into the mechanisms of drought as they are represented in the output of global climate models and on attempting to assess the reliability of these models in simulating drought.Summer drought is often, but not always, accompanied by periods of extreme daily maximum temperatures or "heat waves", the physical link being that changes in the surface energy balance favor increased sensible heating during drought. While climate model projections agree that 21st century surface air temperatures are likely to increase over most land areas (favoring heat waves), considerable uncertainty surrounds the projected changes of precipitation (and therefore of drought), particularly on regional scales. This project is a first look at the joint occurrence of heat waves and drought in newly available climate change projections. The deleterious consequences of the simultaneous occurrence of these extremes make the topic of great practical, as well as scientific, interest.The research will focus on the highly vulnerable, drought-prone region of southern Africa. The investigators will make initial efforts to address the following open questions: How well do coupled models reproduce the observed statistics of joint drought/heat waves over the last half-century? How does this joint occurrence change in 21st century climate projections? To what extent can any such changes be related to changes in surface fluxes? Various meteorological drought indicators based on precipitation, as well as precipitation minus surface evaporation, will be considered. A warmer climate generally increases the probability of extreme daily temperatures and is expected to intensify surface drying in summer. With precipitation projections less clear, the study may provide insight into changes in the relative roles of temperature and precipitation on the joint occurrence of heat waves and drought in climate change projections.Broader impacts of these studies stem from the impacts on food production of drought when it is coupled with severe heat, which increases water losses from crops and stresses livestock. Improved knowledge of the risk of combined droughts and heat waves, as well as the changes in this risk in the 21st century, will be valuable to decision makers in the agricultural and food distribution sectors.

这是气候变率和可预测性（CLIVAR）计划试点项目DRICOMP的一笔赠款，用于耦合模式项目中的干旱，该项目的重点是对全球气候模式输出中所代表的干旱机制进行初步探索，并试图评估这些模式在模拟干旱方面的可靠性。夏季干旱经常，但并不总是，与此同时，还伴随着极端的日最高温度或“热浪”，其物理联系是，干旱期间地表能量平衡的变化有利于增加显热。 虽然气候模型预测一致认为，21世纪世纪大部分陆地地区的地表气温可能会增加（有利于热浪），但预测的降水变化（因此也包括干旱）存在相当大的不确定性，特别是在区域尺度上。 该项目是对新的气候变化预测中热浪和干旱联合发生的第一次考察。 这些极端情况同时发生的有害后果使这一专题具有很大的实际意义和科学意义，研究将集中在南部非洲极易受干旱影响的区域。 研究人员将做出初步努力，以解决以下悬而未决的问题：如何以及耦合模型重现联合干旱/热浪在过去半个世纪的观测统计数据？ 在21世纪世纪气候预测中，这种联合发生的变化如何？ 这些变化在多大程度上与地表通量的变化有关？ 将考虑基于降水量的各种气象干旱指标以及降水量减去地面蒸发量。 温暖的气候通常会增加极端日温的可能性，预计会加剧夏季的地表干燥。 由于降水预测不太清楚，这项研究可能会深入了解气候变化预测中温度和降水对热浪和干旱联合发生的相对作用的变化。这些研究的更广泛影响源于干旱对粮食生产的影响，当干旱与酷热相结合时，会增加农作物的水分损失并给牲畜带来压力。 更好地了解干旱和热浪相结合的风险，以及这种风险在世纪的变化，对农业和粮食分配部门的决策者来说是很有价值的。