Spatiotemporal variability of summer precipitation and precipitation extremes and associated large-scale mechanisms in Central Asia during 1979–2018

Abstract

The spatiotemporal variability of precipitation extremes dramatically affects various socio-economic activities in dryland. Based on the long-term and high-resolution daily precipitation obtained from the National Oceanic and Atmosphere Administration (NOAA) Climate Prediction Center (CPC), the total summer precipitation (TSP), precipitation extreme and persistent precipitation extreme (PPE) characteristics are revealed in Central Asia (CA) (34.3°N–55.4°N and 46.5°E–96.4°E) during 1979–2018. Results show that TSP, precipitation extreme and PPE in CA are significantly increased and the abrupt increasing occurred mainly in 1998. Additionally, proportion of precipitation extreme in TSP also increases. More significant positive trends of TSP, precipitation extreme and PPE occur in zones of northern Kazakhstan (NKZ) and Tienshan mountain range (TSM). Notably, although PEP in other regions exhibit indistinctive changes, PPE in some particular years abnormally frequent which may leads disasters. Further analyses indicate TSP and precipitation extreme in CA have significant positive correlation with the increasing water vapor transport from the southern boundary. Meanwhile, increasing horizontal moisture advection and enhanced vertical moisture advection, contributes to increasing in TSP and precipitation extreme in NKZ and TSM. In addition, negative phase of East Atlantic/West Russia (EA/WR) may result in the cyclone anomalous and deepened trough over CA, which cooperates with enhanced vertical advection and abnormal south moisture, finally provides favorable conditions for precipitation and precipitation extreme.