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.
