Linkage of the Circumglobal Teleconnection and the Interannual Variability of Early Spring Diabatic Heating over Low-Latitude Highlands in Southeast Asia

Abstract

Abstract This study explores the linkage of the circumglobal teleconnection (CGT) on the variability of early spring diabatic heating over the Southeast Asian low-latitude highlands (SEALLH) using ERA5 data. The early spring diabatic heating over the SEALLH shows significant interannual variability with a quasi-3-yr period. Anomalies in the advection of the early spring diabatic heating in the troposphere over the SEALLH associated with CGT are mainly responsible for the interannual variability of early spring diabatic heating over the SEALLH. When CGT is in phase with an anomalous cyclone over the eastern midlatitude North Atlantic, an anomalous cyclone usually dominates the west SEALLH throughout the troposphere. Stronger-than-normal southerly winds located on the east flank of the anomalous cyclone in the lower–upper troposphere transport more high-enthalpy air mass from lower latitudes to the SEALLH and then result in stronger-than-normal early spring diabatic heating over the SEALLH. When CGT is in phase with an anomalous anticyclone over the eastern North Atlantic, the opposite conditions occur, and weaker-than-normal early spring diabatic heating is observed over the SEALLH. Such significant correlation between CGT and early spring diabatic heating over the SEALLH can persist from winter to early summer. The key physical processes revealed in the observational analysis are mostly confirmed by the historical simulation performed with the EC-EARTH3 model. Significance Statement The low-latitude highlands in Southeast Asia are one of the earliest diabatic heating sources in the Asian summer monsoon region. Variability of diabatic heating over the low-latitude highlands in Southeast Asia significantly regulates the weather and climate over the Asian summer monsoon region. However, the interannual variability of early spring diabatic heating over the low-latitude highlands in Southeast Asia remains unclear. This study determines that the circumglobal teleconnection links with the interannual variability of early spring diabatic heating over the low-latitude highlands in Southeast Asia via modulating the local advection process from the previous winter. These results build a bridge connecting the anomalous signals occurring in the upper reaches of the low-latitude highlands in Southeast Asia with the weather and climate in the local and lower reaches of the low-latitude highlands in Southeast Asia.