Modulation of Monsoon Circulations by Cross-Equatorial Ocean Heat Transport
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jcli-d-18-0623.1.pdf
Description
Published version
Size
3.46 MB
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Checksum (MD5)
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Author(s)
Lutsko, Nicholas J.
Marshall, John C.
Green, Brian
Date Issued
May 2019
Journal
Journal of Climate
Publisher
American Meteorological Society
Citation
Lutsko, Nicholas J. et. al., "Modulation of Monsoon Circulations by Cross-Equatorial Ocean Heat Transport." Journal of Climate 32, 12 (May 2019): 3471-85 doi. 10.1175/JCLI-D-18-0623.1 ©2019 Authors
Version
Final published version
Abstract
Motivated by observations of southward ocean heat transport (OHT) in the northern Indian Ocean during summer, the role of the ocean in modulating monsoon circulations is explored by coupling an atmospheric model to a slab ocean with an interactive representation of OHT and an idealized subtropical continent. Southward OHT by the cross-equatorial cells is caused by Ekman flow driven by southwesterly monsoon winds in the summer months, cooling sea surface temperatures (SSTs) south of the continent. This increases the reversed meridional surface gradient of moist static energy, shifting the precipitation maximum over the land and strengthening the monsoonal circulation, in the sense of enhancing the vertical wind shear. However, the atmosphere's cross-equatorial meridional overturning circulation is also weakened by the presence of southward OHT, as the atmosphere is required to transport less energy across the equator. The sensitivity of these effects to varying the strength of the OHT, fixing the OHT at its annual-mean value, and to removing the land is explored. Comparisons with more realistic models suggest that the idealized model used in this study produces a reasonable representation of the effect of OHT on SSTs equatorward of subtropical continents, and hence can be used to study the role of OHT in shaping monsoon circulations on Earth. ©2019 American Meteorological Society.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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DOI of Published Version
https://doi.org/10.1175/JCLI-D-18-0623.1
