Quantifying the Spatial Characteristics of the Moisture Transport Affecting Precipitation Seasonality and Recycling Variability in Central Asia

Moisture contribution and transport pathways for Central Asia (CA) are quantitatively examined using the Lagrangian water cycle model based on reanalysis and observational data to explain the precipitation seasonality and the moisture transport variation during 1979–2015. Westerly-related (northwesterly and westerly) transport explains 42% of CA precipitation and dominates in southwest CA, where precipitation is greatest in the cold season. Southeast CA, including part of Northwest China, experiences its maximum precipitation in the warm season and is solely dominated by southerly transport, which explains about 48% of CA precipitation. The remaining 10% of CA precipitation is explained by northerly transport, which steadily impacts north CA and causes a maximum in precipitation in the warm season. Most CA areas are exposed to seasonally varying moisture transport, except for southeast and north CA, which are impacted by southerly and northerly transport year-round. In general, the midlatitude westerlies-driven transport and the Indian monsoon-driven southerly-related transport explain most of the spatial differences in precipitation seasonality over CA. Moreover, the contribution ratio of local evaporation in CA to precipitation exhibits significant interdecadal variability and a meridionally oriented tripole of moisture transport anomalies. Since the early 2000s, CA has experienced a decade of anomalously low local moisture contribution, which seems jointly determined by the weakened moisture contribution from midlatitudes (the Atlantic, Europe, and CA itself) and the enhanced contribution from high latitudes (West Siberia and the Arctic) and tropical areas (South Asia and the Indian Ocean).