Influence of the Tropical Indian Ocean Tripole on Summertime Cold Extremes Over Central Siberia

Abstract

AbstractThis study investigates the influence of the interannual variability of Indian Ocean tripole (IOT) on summertime cold extremes in Central Siberia. During positive IOT phases, two cross‐equatorial airflows are induced over the tropical eastern and western Indian Ocean. These strengthen ascending motion over the southern tropical Asia (80°–125°E, 15°–25°N), increasing precipitation in situ, as evidenced in observations and simulations by using Community Atmosphere Model. Serving as a heat source, the induced upper‐level Asian continent meridional teleconnection (ACMT) pattern transports the signals from southern tropical Asia into Central Siberia. Positive upper‐level geopotential height anomalies over Central Siberia induced by ACMT favor more solar radiation to reach the surface and raise local surface temperatures through modulating the tropospheric air expansion/compression, further reducing the extreme cold days. Consequently, the ACMT induced by latent heat fluxes associated with precipitation anomalies acts as an atmospheric bridge that links the IOT to Central Siberia cold extremes.