In:
Earth System Dynamics, Copernicus GmbH, Vol. 13, No. 2 ( 2022-04-13), p. 809-831
Abstract:
Abstract. We investigate the effect of variable marine biogeochemical light
absorption on Indian Ocean sea surface temperature (SST) and how this
affects the South Asian climate. In twin experiments with a regional Earth
system model, we found that the average SST is lower over most of the domain
when variable marine biogeochemical light absorption is taken into account,
compared to the reference experiment with a constant light attenuation
coefficient equal to 0.06 m−1. The most significant deviations (more than
1 ∘C) in SST are observed in the monsoon season. A considerable
cooling of subsurface layers occurs, and the thermocline shifts upward in
the experiment with the activated biogeochemical impact. Also, the
phytoplankton primary production becomes higher, especially during periods
of winter and summer phytoplankton blooms. The effect of altered SST
variability on climate was investigated by coupling the ocean models to a
regional atmosphere model. We find the largest effects on the amount of
precipitation, particularly during the monsoon season. In the Arabian Sea,
the reduction of the transport of humidity across the Equator leads to a
reduction of the large-scale precipitation in the eastern part of the basin,
reinforcing the reduction of the convective precipitation. In the Bay of
Bengal, it increases the large-scale precipitation, countering convective
precipitation decline. Thus, the key impacts of including the full
biogeochemical coupling with corresponding light attenuation, which in turn
depends on variable chlorophyll a concentration, include the enhanced
phytoplankton primary production, a shallower thermocline, and decreased SST and
water temperature in subsurface layers, with cascading effects upon the
model ocean physics which further translates into altered atmosphere
dynamics.
Type of Medium:
Online Resource
ISSN:
2190-4987
DOI:
10.5194/esd-13-809-2022
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2022
detail.hit.zdb_id:
2578793-7
