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|Title: || Variability of wind stress curl over the Indian Ocean during years 1970-1995 |
|Authors: ||Rao, A.D.|
|Keywords: ||Interannual variability;Indian Ocean;surface curl;EOF analysis;harmonic analysis|
|Issue Date: ||Jun-2002|
|Abstract: || Climatological and interannual variability aspects of monthly mean pseudo-stress curl over the Indian Ocean for the period 1970-1995 are explored. A harmonic analysis of the curl fields finds most of the variance of the northern basins dominated by semi-annual variability. In particular the coastal areas of Somalia and south/southwestern India have large contributions from this harmonic. In the southern basin, interannual harmonics are the primary ones of curl variance. Biennial oscillatory behaviour is only sporadically evident in various harmonics between 20 and 30 months, and was absent north of 10°S. An EOF analysis confirms that the summer monsoon is the dominant feature compared to the wintermonsoon. The mean positive curl in the eastern Arabian Sea indicated positive Ekman velocities (upwards) enhancing coastal upwelling in this region. More exceptional and not previously noted factor is an opposite and somewhat dramatic reduction of curl magnitude since 1988/89. The rate of decline is much larger than the (positive) trend in the early 1980’s and was most notable in the early part of the summer monsoon. It is also evident in the winter monsoon periods, but not so for other months of the year. Additional evidence supports this change in variability patterns. |
|Appears in Collections:||IJMS Vol.31(2) [June 2002]|
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