Moisture sources associated with precipitation during dry and wet seasons over Central Asia

Abstract

Identifying the origin of moisture is a key process in revealing the formation mechanisms of precipitation, but the moisture sources for Central Asia have not been well documented in previous studies. In this work, we employ the Lagrangian model FLEXPART over 2011-2019 to address this question. Multiple observational products indicate that the times of dry and wet seasons are opposite for western and eastern Central Asia bounded by 75 ° E. The wet season is November-December-January-February-March-April (NDJFMA) for western but May-June-July-August-September-October (MJJASO) for eastern Central Asia, while the opposite is true for the dry season. The main moisture-source regions for western Central Asia are local regions (with a contribution of 49.11%), West Eurasia (21.47%), and West Asia (11.37%) during MJJASO and local regions (33.92%), West Asia (27.50%), and West Eurasia (17.60%) during NDJFMA. For eastern Central Asia, moisture mainly originates from local regions (52.38%), western Central Asia (25.22%), and North Eurasia (9.26%) during MJJASO and western Central Asia (30.86%), local regions (30.82%), West Asia (10.31%), and West Eurasia (10.26%) during NDJFMA. The differences in moisture sources between dry and wet seasons mainly occur in local regions and West Asia for western but in local regions for eastern Central Asia. The moisture from North Eurasia, West Eurasia, and western Central Asia is transported into target regions by the westerly and southwesterly that is associated with a deep low trough over Central Asia. Moisture is transported from West Asia by the anticyclone occurs over North Africa-West Asia in the lower and middle troposphere.