Dr.Babu, C A; Hamza, Varikoden; Samah, A A(May 14, 2009)
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Abstract:
A distinct cold tongue has recently been noticed in the South China Sea during the winter monsoon,
with the cold tongue temperature minimum occurring in the January or February. This cold tongue shows
signi¯cant links with the Maritime Continent's rainfall during the winter period. The cold tongue and
its interaction with the Maritime Continent's weather were studied using Reynolds SST data, wind ¯elds
from the NCEP{NCAR reanalysis dataset and the quikSCAT dataset. In addition, rainfall from the GOES
Precipitation Index (GPI) for the periods 2000 to 2008 was also used. The propagation of the cold tongue
towards the south is explained using wind dynamics and the western boundary current. During the period
of strong cold tongue, the surface wind is strong and the western boundary current advects the cold tongue
to the south. During the period of strong winds the zonal gradient of SST is high [0.5±C (25 km)¡1]. The
cold tongue plays an important role in regulating the climate over the Maritime Continent. It creates a
zonal/meridional SST gradient and this gradient ultimately leads in the formation of convection. Hence,
two maximum precipitation zones are found in the Maritime Continent, with a zone of relatively lower
precipitation between, which coincides with the cold tongue's regions. It was found that the precipitation
zones have strong links with the intensity of the cold tongue. During stronger cold tongue periods the
precipitation on either side of the cold tongue is considerably greater than during weaker cold tongue
periods. The features of convection on the eastern and western sides of the cold tongue behave di®erently.
On the eastern side convection is preceded by one day with SST gradient, while on the western side it is
four days.
Description:
ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 27, NO. 2, 2010, 265{273