Land surface signal of the Indochina Peninsular precipitation variability during the early rainy season

Abstract

AbstractThe precipitation variability is subject to impacts of both ocean and land surface condition changes. The present study investigates the role of land surface condition in the interannual variation of the early rainy season (May–June) precipitation over the Indochina Peninsula. A precursory signal is identified in surface air temperature (SAT) during March–April over central Asia after the late 1970s. The air temperature anomalies extend to middle troposphere and persist to early summer (May–June) and modulate the land‐sea thermal contrast and lower‐level and upper‐level winds over the North Indian Ocean and thus affect the early rainy season precipitation over the Indochina Peninsula. The maintenance of SAT anomalies over central Asia is related to that of surface heat flux anomalies that in turn is attributed to the persisting atmospheric wind anomalies. The precursory signal is weak before the late 1970s due to the lack of persisting atmospheric wind anomalies. The interdecadal change in the persistence of central Asian SAT anomalies is associated with a difference in the distribution of the North Atlantic sea surface temperature (SST) anomalies. After the late 1970s, the North Atlantic SST anomalies with a southwest‐northeast distribution excite a wave train that extends from the North Atlantic to central Asia during May–June. Before the late 1970s, the wave train associated the North Atlantic SST anomalies with a south–north distribution is confined to the North Atlantic region.