RAPID: Decadal Variability of the American Monsoons--An Assessment of CMIP5 Simulation

这是政府间气候变化专门委员会第五次评估报告（IPCC AR5）中鼓励对气候模式模拟进行诊断分析的致同事信（NSF 11-006）资助的16个快速响应（Rapid）项目之一。在这些项目中进行的研究预计将导致更详细的模式相互比较，更好地理解稳健模式行为，更好地理解和量化未来气候模拟中的不确定性。本项目考察了气候模式比较项目第5期（CMIP5）最近对美国季风系统（AMS）的模拟。主要目标是对模拟在最近的过去表现美国季风系统（AMS）观测特征方面的真实程度进行广泛评估，并评估AMS预测的年代际气候变化的不确定性。更具体地说，该项目评估了CMIP5模式模拟美洲季风的气候和统计特征的能力，包括：环流和降水特征、亚季节变化、开始和消失、振幅和跨赤道转变。2)确定哪些CMIP5模式真实地反映了当前气候下季风的时空变化，包括近期趋势、极干湿季频率和极端降水事件的统计分布。3)考察哪些CMIP5模式能很好地反映观测到的远程强迫与美洲季风之间的关系。这些包括麦登-朱利安涛动（MJO）、厄尔尼诺Niño/南方涛动（ENSO）、北大西洋涛动（NAO）、太平洋年代际涛动（PDO）、南极涛动（AAO）、大西洋和美洲内部海强迫。4)试图确定未来几十年预计的美洲气候变化有多少是由自然年代际变率解释的，有多少是由温室气体增加解释的。该项目的更广泛影响在于它对IPCC第五次评估报告的支持，该报告旨在向全球决策者提供有关气候变化及其后果的信息。农业辅助系统影响着整个美洲人口稠密地区的水资源、农业、人类健康、生态系统和生物多样性。气候变化对AMS的影响尚不清楚，这项研究将有助于确定用于预测气候变化的模式在多大程度上能够准确地代表AMS系统及其在观测记录上的变率和变化。

This is one of 16 Rapid Response (RAPID) projects funded as the result of a Dear Colleague Letter (NSF 11-006) encouraging diagnostic analyses of climate model simulations prepared for the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5). Research conducted in these projects is expected to lead to more detailed model intercomparisons, better understanding of robust model behaviors, and better understanding and quantification of uncertainty in future climate simulations.This project examines the simulation of the American Monsoon System (AMS) in simulations of the recent past from the Climate Model Intercomparison Project verson 5 (CMIP5). The main goals are to develop an extensive assessment of how realistic simulations are in representing the observed characteristics of the American Monsoon System (AMS) in the recent past, and to assess uncertainties in projected decadal climate changes in the AMS. More specifically, the project1) Assesses the skill of CMIP5 model simulations in representing the climatological and statistical characteristics of the monsoons in the Americas including: circulation and precipitation features, subseasonal variance, onsets and demises, amplitudes and cross equatorial transitions.2) Determines which CMIP5 models realistically represent the spatiotemporal variability of the monsoons in the present climate including near-term trends, frequency of very dry/wet seasons and statistical distributions of extreme precipitation events.3) Examines which CMIP5 models skillfully represent the observed relationships between remote forcings and the American monsoons. These include the Madden-Julian Oscillation (MJO), El Niño/Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), Antarctic Oscillation (AAO), Atlantic Ocean and Intra-Americas Sea forcings.4) Seeks to determine how much of the climate changes projected for the next decades in the Americas are explained by natural decadal variability and how much by greenhouse gases increases.The broader impact of the project lies in its support of the IPCC AR5, which is intended to provide information on climate change and its consequences to decision makers worldwide. The AMS affects water resources, agriculture, human health, ecosystems and biodiversity throughout a large and densely populated portion of the Americas. The impact of climate change on the AMS is not known, and this research will help to determine the extent to which models used to project climate change are capable of accurately representing the AMS system and its variability and change over the observed record.