Weakening trend of the tropical easterly jetstream of the boreal summer monsoon season 1950 - 2009

TitleWeakening trend of the tropical easterly jetstream of the boreal summer monsoon season 1950 - 2009
Publication TypeJournal Article
Year of Publication2013
AuthorsAbish, B, Joseph, PV, Johannessen, OM
JournalJournal of Climate
Volume26
PublisherAmerican Meteorological Society
ISSN0894-8755
Abstract

Recent research has reported that the tropical easterly jet stream (TEJ) of the boreal summer monsoon season is weakening. The analysis herein using 60 yr (1950–2009) of data reveals that this weakening of the TEJ is due to the decreasing trend in the upper tropospheric meridional temperature gradient over the area covered by the TEJ. During this period, the upper troposphere over the equatorial Indian Ocean has warmed due to enhanced deep moist convection associated with the rapid warming of the equatorial Indian Ocean. At the same time, a cooling of the upper troposphere has taken place over the Northern Hemisphere subtropics including the Tibetan anticyclone. The simultaneous cooling of the subtropics and the equatorial heating has caused a decrease in the upper tropospheric meridional thermal gradient. The consequent reduction in the strength of the easterly thermal wind has resulted in the weakening of the TEJ.

DOI10.1175/JCLI-D-13-00440.1
Refereed DesignationRefereed
Author Address

NERSC

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