SGER: Stochastic Characteristics of Drought and Surface-Atmosphere Drought Forcing in Coupled General Circulation Models (GCMs)

这是气候变异性和可预测性(CLIVAR)计划试点项目DRICOMP下的一项拨款，用于耦合模式干旱项目，重点是对干旱的机制进行初步探索，因为它们代表了全球气候模型的输出，并试图评估这些模型在模拟干旱方面的可靠性。干旱是美国代价最高的自然灾害，仅在美国每年平均影响就达到60-80亿美元。然而，人们对导致干旱的物理和动力机制以及气候变化对干旱特征的潜在影响知之甚少。这项研究是回答两个研究问题的初步尝试：。地表-大气相互作用在多大程度上推动了干旱的随机特征，包括干旱持续时间、干旱程度和选定地区的复发？人为气候变化将如何影响导致干旱的物理和动力机制，以及随后干旱的随机特征？干旱的随机特征将根据观测的气候数据和世界气候研究计划耦合模式相互比较项目(WCRP CMIP3)数据档案中所有19个20世纪瞬时耦合气候模拟数据在全球范围内进行评估。将使用复合分析和多元回归分析相结合的方法，努力客观地确定与干旱事件有关的前期和同期海表面温度(SST)和土壤湿度(仅限模拟)的具有统计意义的模式。然后，将根据地面异常合成的幅度和稳健性和多重回归系数来评估地面-大气强迫在干旱事件的开始、持续和衰退中的作用。结果将在观测和模拟之间以及模型之间进行比较。最后，将在CMIP3数据档案中对所有成对的工业化前控制和强迫稳定化模拟重复分析；将通过比较所有模式的控制模拟和强迫稳定化模拟之间的干旱特征和地面-大气干旱强迫来评估气候变化的潜在影响。更广泛的影响将是提高我们对干旱的随机性质和导致干旱事件的物理机制的了解；这些分析将有助于改进干旱规划和管理。

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.Droughts are the nation's costliest natural disasters, with average annual impacts of $6-8 billion in the United States alone. The physical and dynamical mechanisms that lead to drought and the potential impacts of climate change on drought characteristics are, however, only poorly understood. This study represents an initial attempt to answer two research questions: . To what degree do surface-atmosphere interactions drive the stochastic characteristics of drought, including drought duration, magnitude, and recurrence, over selected regions? . How will anthropogenic climate change affect the physical and dynamical mechanisms that lead to drought, and subsequently the stochastic characteristics of drought? Stochastic characteristics of drought will be evaluated globally based on observed climate data and all 19 transient twentieth-century coupled climate simulations in the World Climate Research Program Coupled Model Intercomparison Project (WCRP CMIP3) data archive. A combined composite and multiple regression analysis will be used in an effort to objectively identify statistically significant patterns of antecedent and contemporaneous sea surface temperature (SST) and soil moisture (simulations only) associated with drought events. The role of surface-atmosphere forcing in the onset, persistence, and recession of drought events will then be assessed based on the amplitude and robustness of surface anomaly composites and multiple regression coefficients. Results will be compared between observations and simulations, and between models. Finally, the analysis will be repeated for all paired pre-industrial control and forced stabilization simulations in the CMIP3 data archive; potential impacts of climate change will be evaluated by comparing the drought characteristic and surface-atmosphere drought forcing between the control and forced stabilization simulations for all models. Broader impacts will be to improve our understanding of the stochastic nature of drought and the physical mechanisms that lead to drought events; the analyses will help to improve drought planning and management.