Collaborative Research: WCR: Hydrology of Central and Southwest Asia: Connections Between Regional Atmospheric Circulation and Large-scale Climate Variability

严重干旱是中亚和西南亚（CSW）亚洲水文的显著特征。在大约1998年11月至2002年底的4年期间，该地区经历了异常严重的干旱，造成了毁灭性的社会和环境后果。在此期间，干旱造成世界上任何地方持续降水不足的面积最大，是当地50多年来最严重的干旱。最近的研究表明，大尺度的、潜在可预测的气候变率是亚洲西南地区降水的一个重要因素，并在最近的干旱中发挥了主要作用。为了探讨大尺度气候变率所提供的潜在可预测性，本文分析了南亚区域水循环亏缺的关键机制。由于天气风暴作为亚洲西南地区降水生成机制的重要性，区域水文异常与高层风型的变化有关。反过来，这些区域大气流动模式既可以受到来自西部的大西洋变化的影响，也可以受到来自东部的印度-西太平洋变化的影响。这些联系及其潜在的可预测性通过以下观察分析来检验：(1)河流流量的区域尺度波动；(2)这些波动与控制水汽输送到该区域的区域大气环流关键特征之间的联系；(3)大尺度气候变率对区域环流的影响，特别强调北大西洋涛动（NAO）、厄尔尼诺-南方涛动（ENSO）和东印度洋对流极大值。这项研究的目标之一是发展与区域救济工作以及农业、水资源和保健系统的管理和重建有关的气候资料。

Severe drought is a notable feature of the hydrology of Central and Southwest Asia (CSW) Asia. During the 4-year period from approximately November 1998 through the end of 2002, the region experienced an exceptionally severe drought, with devastating societal and environmental consequences. The drought comprised the largest area of persistent precipitation deficits anywhere in the world during that period and was locally the most severe drought in over 50 years. Recent research suggests that large-scale, potentially predictable, climate variability is an important factor in CSW Asia precipitation and played a primary role in the recent drought. To explore the potential predictability provided by large-scale climate variability, the key mechanisms for deficits in the regional water cycle of CSW Asia are analyzed.Due to the importance of synoptic storms as a precipitation-generation mechanism in CSW Asia, regional hydrologic anomalies are related to variations in the upper-level wind patterns. These regional atmospheric flow patterns, in turn, can be affected both from the west, by Atlantic variability, and from the east, by Indo-West Pacific variability. These connections and their potential predictability are examined through observational analysis of: (1) regional-scale fluctuations in river flows, (2) the links between these fluctuations and key features of the regional atmospheric circulation that control moisture transport into the region, and (3) the influence of large-scale climate variability on the regional circulation, with particular emphasis on the North Atlantic Oscillation (NAO), the El Nino-Southern Oscillation (ENSO), and the eastern Indian Ocean convective maximum.One of the goals of this research is the development of climate information relevant to regional relief effort and management and reconstruction of agriculture, water resources, and health systems.