Remote Insolation Forcing of Orbital‐Scale South Asian Summer Monsoon Variability

Abstract

Abstract Whether the South Asian summer monsoon (SASM) is controlled by local or remote insolation at the orbital band remains uncertain. Here, we perform a transient simulation forced by Earth's orbital parameters between 400 and 350 ka BP, a period characterized by significant contrast between local and remote insolation, to identify the SASM's response to insolation forcing. Simulation results suggest that the primary driver of orbital‐scale SASM variability is the Northern Hemisphere high‐latitude June insolation, as opposed to local insolation. High June insolation in the Southern Hemisphere might reduce the SASM intensity. Remote insolation influences the SASM by altering the latitudinal thermal gradient and, consequently, the meridional position of the South Asian high (SAH). The SAH is associated with intense convection and hence drives the meridional shift of the intertropical convergence zone and the SASM rain belt. Thus, orbital‐scale SASM variability is strongly related to remote insolation forcing.

Keywords

• South Asian summer monsoon
• South Asian high
• climate simulation
• orbital forcing