Early prediction of onset of south west monsoon from ERS-1 scatterometer winds |
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Authors: | U R Rao P S Desai P C Joshi P C Pandey B S Gohil B Simon |
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Institution: | (1) ISRO Headquarters, Antariksh Bhavan, Bangalore, India;(2) Meteorology and Oceanography Group, Space Applications Centre (ISRO), 380 053 Ahmedabad, India |
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Abstract: | Detailed analysis of the surface winds over the Indian Ocean derived from ERS-1 scatterometer data during the years 1993 and
1994 has been used to understand and unambiguously identify the onset phase of south-west monsoon. Five day (pentad) averaged
wind vectors for the period April to June during both years have been examined to study the exact reversal of wind direction
as well as the increase in wind speed over the Arabian Sea in relation to the onset of monsoon over the Indian west coast
(Kerala). The related upper level humidity available from other satellites has also been analysed.
The results of our analysis clearly show a consistent dramatic reversal in wind direction over the western Arabian Sea three
weeks in advance of the onset of monsoon. The wind speed shows a large increase coinciding with the onset of monsoon. These
findings together show the dominant role of sea surface winds in establishing the monsoon circulation. The study confirms
that the cross equatorial current phenomenon becomes more important after the onset of monsoon. |
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Keywords: | Monsoon prediction cross equatorial winds ocean surface winds scatterometer |
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