Mesoscale Modeling of Tropical Paleoclimate

热带古气候的中尺度模拟

• 批准号: 0123797
• 负责人: Kerry Cook
• 金额: $ 26.06万
• 依托单位: Cornell Univ - State: AWDS MADE PRIOR MAY 2010
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0123797&HistoricalAwards=false
• 关键词: Mesoscale; Modeling; Tropical; Paleoclimate

This award will serve to develop and apply a mesoscale modeling system for studying past variability in tropical climates of Africa and South America during the Last Glacial Maximum (LGM). The modeling system consists of two models. A mesoscale climate model (MCM) will simulate climate on space scales of tens of kilometers. A general circulation model (GCM) will generate lateral boundary conditions on wind, temperature, and moisture for the mesoscale model. Simulations of the dry climates of the present day and LGM (~21,000 years ago) over northern Africa will be contrasted with simulations for the African Humid Period, approximately 6,000 years ago when Sahelian and Saharan Africa supported numerous lakes and extensive vegetation. The research will address the following questions:-What are the individual and combined roles of insolation, changes in land surface conditions, regional SST differences, and differences in large-scale climate (i.e., MCM lateral boundary conditions) in causing differences in surface wetness over northern Africa among the present day, African Humid Period and the LGM?-Are the differences in wetness associated with changes in precipitation only, or do changes in evaporation and/or water table levels play an important role?-What mechanisms are involved in changing the atmospheric column water vapor budget? -Are any important mechanisms nonlinear in a way that helps explain the speed with which the climate can change in this region? What are the implications for future climate change (global warming)?Simulations with various combinations of lateral and surface boundary conditions, as well as other forcing functions such as insolation and atmospheric composition, will identify the important factors and physical mechanisms that lead to the wet conditions and the rapid climate change that is hypothesized to have occurred in Amazonia during the Holocene. The mesoscale modeling system will also be used to study South American climate of the LGM.The research will address the following questions:-What was the distribution of drying and cooling during the LGM in the Amazon Basin and what mechanisms are associated with the differences from the present day climate?-What differences in aridity in the Central Andes are simulated with the MCM, and what mechanisms account for differences from the present day?-How are the simulated differences in both regions related to global-scale climate conditions and how are they linked?-Does the model support the idea that there are different aridity trends in different areas of the high Central Andes? If so, are these trends providing information about inter-hemispheric symmetry or asymmetry of climate change during the last glacial cycle?

该奖项将用于开发和应用中尺度建模系统，用于研究末次盛冰期（LGM）期间非洲和南美洲热带气候的过去变化。建模系统由两个模型组成。中尺度气候模型（MCM）将模拟数十公里空间尺度的气候。一般环流模型 (GCM) 将为中尺度模型生成风、温度和湿度的横向边界条件。 对北非当今干燥气候和末次盛会（约 21,000 年前）的模拟将与对大约 6,000 年前非洲湿润期的模拟进行对比，当时萨赫勒和撒哈拉非洲支持着众多的湖泊和广泛的植被。该研究将解决以下问题：-日照、地表条件变化、区域海温差异以及大尺度气候差异（即MCM横向边界条件）在导致地表湿度差异方面的单独作用和综合作用是什么现今、非洲湿润期和末次盛冰期期间北非上空的变化？-湿度的差异是否仅与降水的变化有关，还是蒸发和/或地下水位的变化起着重要作用？-涉及哪些机制？改变大气柱水蒸汽预算？ -是否有任何重要的非线性机制可以帮助解释该地区气候变化的速度？对未来气候变化（全球变暖）有何影响？对横向和地表边界条件的各种组合以及日照和大气成分等其他强迫函数进行模拟，将确定导致潮湿的重要因素和物理机制。假设在全新世期间发生在亚马逊流域的条件和快速气候变化。中尺度模拟系统还将用于研究末次盛冰期的南美气候。该研究将解决以下问题：-末次盛冰期期间亚马逊河流域干燥和变冷的分布情况如何，以及与末次盛冰期的差异相关的机制是什么？当前的气候？-MCM 模拟了安第斯山脉中部的干旱有哪些差异，以及哪些机制可以解释与当前的差异？-这两个地区的模拟差异与全球范围的气候条件有何关系？他们有联系吗？-模型有吗支持安第斯山脉中部高地不同地区有不同干旱趋势的观点吗？如果是这样，这些趋势是否提供了有关末次冰期期间气候变化的半球对称性或不对称性的信息？