Dominant role of Eurasian evaporation on the moisture sources of the interannual variations in Central Asian summer precipitation

Abstract

Abstract The precipitation changes in arid and semi-arid Central Asia have great impacts on the local fragile ecosystem. The summer precipitation in Central Asia shows obvious interannual variations, but the corresponding crucial moisture transporting processes remain unclear. Therefore, this study employs the Lagrangian model FLEXPART to achieve this goal. Results show that the moisture of climatological summer precipitation in Central Asia is mainly from the local regions, the surrounding Western and Northern Eurasian regions. The contribution of local evaporation from Western Central Asia is about two times of that from Eastern Central Asia. At the interannual timescale, the moisture variations are mainly influenced by the local regions and the Western Eurasia, while the local evaporation is mainly from western Central Asia. Totally, the Eurasian evaporation plays a dominant role in the interannual variations of Central Asian summer precipitation by contributing more than 90% of the total moisture. The moisture transports associated with Central Asian summer precipitation interannual variations are impacted by the anomalous cyclones over western and northeastern part of Central Asia during the wet years, which enhance the moisture convergence and hence increase the summer precipitation in Central Asia. The anomalous cyclone over western part of Central Asia is correlated with the changes in intensity of Eurasian Summer Subtropical Westerly Jet (ESSWJ), while the anomalous cyclone over northeastern part of Central Asia is correlated with both ESSWJ and the British–Baikal Corridor pattern teleconnection in association with the polar front jet.