TITLE:
Winter-Spring Precipitation Variability in Pakistan
AUTHORS:
Iftikhar Ahmad, Romana Ambreen, Zhaobo Sun, Weitao Deng
KEYWORDS:
Pakistan, Winter-Spring Precipitation, EOF, Spatial Variability, Interannual Variability
JOURNAL NAME:
American Journal of Climate Change,
Vol.4 No.1,
March
27,
2015
ABSTRACT: This study investigates the spatial-temporal variability of winter-spring
(February-March-April) precipitation (WSP) in Pakistan over the period of
1961-2006 by making use of Empirical Orthogonal Function (EOF). The EOF
analysis is based on ground observed data, reanalysis NCEP/NCAR of various
geopotential heights and NOAA extended reconstructed sea surface temperatures
(ERSST.v3). The significant modes are obviously variable at interannual time
scale. The leading mode shows the node of maximum spatial variability anchored
over the Peshawar Valley and Azad Kashmir (PVAK) axis. The pattern is
associated with strong (weak) westerly jet over the Middle East. The pattern is
also found closely associated with post monsoon and early winter El Nino. The Nino4 index can be an appropriate
predictor for the first consistent single node pattern. The second significant
mode represents a tripole pattern with areas of prominent variability over
northwestern Pakistan, Quetta-Kalat region and northeastern Punjab. The pattern
is found to be pro-NAO and in relation to this pattern, warm and stable SST
anomalies appearing in the southern mid-latitudes of Indian and Atlantic
basins.