Geoscience Reference
In-Depth Information
(a)
(b)
Fig. 3 Warm pool a January and b May shown by the mean Hadley Centre Sea Ice and Sea Surface
Temperature (HadISST) data set of 1961-1990. Note the north-westwards shift of the centre of the warm
pool from January to May
(a)
(b)
(
c)
(
d
)
Fig. 4 The mean TRMM Microwave Imager (TMI) SST of pentads. a -7, b -5, c -2 and d 0 during the
year 2003
rainfall (cyclonic vorticity in the low levels associated with the LLJ together with the
friction in the atmospheric boundary layer produce vertical upwards motion of the moist
monsoon air) and for the genesis of monsoon depressions in north BoB. When the cloud
band of the active monsoon passing through central India and the BoB weakens after a life
of 4 or 5 pentads, the LLJ shifts to a position south of India and the raining area gets
located around the equator. This is the beginning of the break phase of the monsoon when
rainfall becomes deficient over central India and the BoB. During this period of break
monsoon, north BoB warms and we get the next active monsoon spell. In a normal
monsoon season, there are 3 active-break cycles of average period of about 40 days. LLJ
