SGER: Diagnosing El Nino-induced Tropical Droughts in Seasonal Forecasts and Climate Change Projections

这是气候变率和可预测性（CLIVAR）计划试点项目DRICOMP下的一笔赠款，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。厄尔尼诺给热带地区带来了广泛的干旱，包括墨西哥和南美洲北方。 未来更强或更频繁的厄尔尼诺现象将加剧这些高度脆弱地区的干旱风险。 即使厄尔尼诺事件的频率和强度在21世纪世纪没有增加，热带太平洋更普遍的变暖仍然可能产生类似于与当今厄尔尼诺条件相关的热带遥相关。业务季节预报是否能够捕捉到造成热带干旱的条件，这是一个完全悬而未决的问题。 本研究是一个初步的探索模式，空间范围，和严重性的厄尔尼诺现象引起的热带干旱在控制期间在20世纪世纪的季节预报，更新现实的初始条件，但固定的温室气体（GHG），并在气候变化预测，有现实的GHG演变，但没有观测更新。 然后，将对21世纪的热带干旱模式强度的预测变化进行审查。 本研究将试图解决以下问题：。耦合模式对20世纪与厄尔尼诺相关的热带干旱的模式和强度的模拟效果如何？20世纪世纪厄尔尼诺季节预报模式与气候变化模式的主要区别是什么？年际降水变化模式在多大程度上预测了21世纪世纪降水趋势，其余趋势的空间特征是什么？该项目的更广泛影响是评估全球气候模型对热带干旱频率和严重程度变化的预测的可信度。 它还可以为“重新校准”全球气候模型的输出提供基础，以提高其预测热带降雨量变化的可靠性。 该项目将支持Caio A的访问。S. Coelho是巴西气象局下属的克里思气候预测中心（CPTEC）的科学家，他将前往美国与首席研究员合作。 这将有助于CPTEC与哥伦比亚大学国际气候与社会研究所之间正在进行的合作。

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.El Nino brings widespread drought to the tropics, including Mexico and northern South America. Stronger or more frequent El Nino events in the future will exacerbate drought risk in these highly vulnerable areas. Even if the frequency and intensity of El Nino events do not increase in the 21st century, more generalized warming of the tropical Pacific may still produce a tropical teleconnection resembling that associated with present-day El Nino conditions. Whether or not operational seasonal forecasts can capture the conditions that cause tropical drought is an entirely open question. This study is an initial exploration of the patterns, spatial extent, and severity of El Nino induced tropical droughts during a control period in the 20th century in seasonal forecasts, which have updated realistic initial conditions but fixed greenhouse gases (GHGs), and in climate change projections, which have realistic GHG evolution but no observational updates. The projected changes in the strength of the identified patterns of tropical drought will then be examined for the 21st century runs. This research will attempt to address the following questions:. How well do coupled models simulate the pattern and intensity of tropical droughts associated with El Nino during the 20th century?. What are the primary differences of El Nino variability and change between seasonal prediction models and climate change models in the 20th century?. To what extent do patterns of interannual precipitation variability project on 21st century precipitation trends, and what is the spatial signature of the remaining trends?Broader impacts of this project are in assessing the credibility of global climate model projections of changes in the frequency and severity of tropical droughts. It may also provide a basis for "recalibrating" the output of global climate models, so as to improve their reliability in projecting changes in tropical rainfall. The project will support the visit of Caio A. S. Coelho, a scientist at the Centro de Previsao de Tempo e Estudos Climaticos (CPTEC), an institute of the Brazilian Meteorological Service, to the United States to collaborate with the principal investigator. This will contribute to an ongoing collaboration between CPTEC and the International Research Institute for Climate and Society (IRI) at Columbia University.