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Satellite observed wind forcing over the southwest equatorial Indian ocean during Indian summermonsoon

Mahajan, PN and Khaladkar, RM and Chinthalu, GR and Rajamani, S (1996) Satellite observed wind forcing over the southwest equatorial Indian ocean during Indian summermonsoon. Journal of Meteorology, 21 (214). pp. 403-412.

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Abstract

In this paper, satellite-observed wind forcing in the form of strong surge of cold air through Mozambique channel and along east African coast, under the influence of eastward propagating baroclinic wave disturbances over southwest Indian ocean has been studied during various summer monsoon seasons. Further, its impact on the intensification of monsoon systems over the Arabian sea through the excitation of low-level jet and associated cross-equatorial flow has been illustrated. For this purpose, satellite-observed cloud imagery, obtained from TIROS-N, NOAA, DMSP, GOES and INSAT satellites during 1979 and 1988-95,have been utilized for finding latitudinal positions of the cold fronts across south African-Malgassy region (i.e. 30°S, I -40°E), GOES(IO) and INSAT derived low level cloud drift winds in the domain 2.5°S to 2.5°N and 40°50°E have been used to observe the triggering of low level jet and associated cross equatorial flow. Daily rainfall of ten stations viz. Tiruvananthapuram, Alleppy, Cochin, Kozikhode, Mangalore, Karwar, Goa, Ratnagiri, Bombay and Dahanu have been used for finding the modulation of the rainfall activity along the west coast of India. From the results of the study it is inferred that there is an abrupt increase in the strength of low-level wind flow along east African coast 2 to 3 days after the first appearence of northward propagating cold front across south African-Malgassy region. This is followed by intensification of the rainbearing monsoon systems (e.g. ITCZ, lows, off shore troughs etc.) over the Arabian sea giving increase in rainfall activity along the west coast of India. Therefore it is suggested that above association between northward-propagating cold front across south African-Malgassy region and excitation of low-level cross-equatorial flow can be linked to forecast increase in rainfall activity alone the west coast of India 5-7 days in advance.

Item Type: Article
Uncontrolled Keywords: baroclinic wave; monsoon; monsoons; satellite image; satellite imagery; summer; wind forcing, Arabian Sea; Indian Ocean, (Equatorial Southwest)
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 20 Feb 2015 09:06
Last Modified: 20 Feb 2015 09:06
URI: http://moeseprints.incois.gov.in/id/eprint/1725

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