Abstract :
Surface and upper air circulation features associated with extreme precipitation years are
demonstrated during winter season viz., December, January, February and March (DJFM) to examine
winter weather affecting the western Himalayas. These circulations are studied over the domain 15 S–45 N
and 30 E–120 E. This domain is considered particularly to illustrate the distribution of precipitation due
to a wintertime eastward moving synoptic weather system called western disturbances. Surplus and
deficient years of seasonal (DJFM) precipitation are identified using ± 20% departure from mean from
uninitialized daily reanalysis data of forty (1958–1997) years of the National Center For Environmental
Prediction (NCEP), US. The years 1965–1969, 1973 and 1991 are found to be surplus years and the years
1962, 1963, 1971, 1977, and 1985 are found to be deficient years. Comparative study between composites of
these two categories is made using students t-test of significance. Significant differences in sea-level
pressure, zonal and meridional component of wind at surface and upper levels, total precipitable water
content, geopotential height and temperature are observed in the two contrasting seasons.
