Weakening of Indian Summer Monsoon Synoptic Activity in Response to Polar Sea Ice Melt Induced by Albedo Reduction in a Climate Model

Abstract

The effect of polar sea ice melt on low latitude climate is little known. To understand the response of the Indian summer monsoon (ISM) synoptic activity to the sea ice melt, we have run a suite of coupled and uncoupled climate model simulations. In one set of simulations, the albedo of sea ice is reduced so that it would melt due to increased absorption of solar radiation. The coupled model simulation with a reduced sea ice albedo resulted in an almost complete melting of the sea ice in summer in both hemispheres. A high‐resolution (50 km) atmospheric general circulation model (AGCM) is forced with the climatological annual cycles of sea surface temperature (SST) and sea ice concentrations (SIC) from the coupled model outputs to better resolve synoptic scale variability. In the high‐resolution AGCM simulations forced with SST and SIC from the sea ice melt experiments, the ISM circulation weakened substantially, and the monsoon low‐pressure systems (LPS) activity experienced an overall decline of 23%, with a widespread weakening in the south and a moderate strengthening over the north, in response to a decline of 78% (24%) in SIC over the Arctic (Antarctic) in the June–September season. The changes in the LPS activity in response to polar sea ice melt are found to be mostly driven by the changes in low‐level absolute vorticity and vertical shear over the Bay of Bengal.

Weakening of western disturbances in response to polar sea ice melt in climate model simulations

“…Each of these runs span for four years, giving a total of sixteen years of data. Similar high-resolution atmospheric model simulations have been performed to investigate the changes in monsoon low-pressure systems (Sandeep et al, 2018;Chandra et al, 2022).…”

“…The polar sea ice melt can also elicit a climate system response similar to that of global warming (England et al, 2020). Recent studies using coupled models suggest that both Arctic and Antarctic sea ice melt can influence changes in the deep tropics (Liu and Fedorov, 2019;England et al, 2020;Chandra et al, 2022). Using climate model simulations, Chandra et al (2022) showed that the Indian summer monsoon circulation and synoptic activity would weaken in response to the polar sea ice melt.…”

“…Using climate model simulations, Chandra et al (2022) showed that the Indian summer monsoon circulation and synoptic activity would weaken in response to the polar sea ice melt. Here, we use the modeling framework from Chandra et al (2022) to investigate the changes in WD activity in response to the polar sea ice melt.…”

“…Recent studies using coupled models suggest that both Arctic and Antarctic sea ice melt can influence changes in the deep tropics (Liu and Fedorov, 2019;England et al, 2020;Chandra et al, 2022). Using climate model simulations, Chandra et al (2022) showed that the Indian summer monsoon circulation and synoptic activity would weaken in response to the polar sea ice melt. Here, we use the modeling framework from Chandra et al (2022) to investigate the changes in WD activity in response to the polar sea ice melt.…”