Author(s)

Iftikhar Ahmad^1*, Romana Ambreen¹, Zhaobo Sun², Weitao Deng²

¹Department of Geography, University of Balochistan, Quetta, Pakistan.
²Key Laboratory of Meteorological Disaster, Ministry of Education, Nanjing University of Information Science & Technology, Nanjing, China.

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.

Pakistan, Winter-Spring Precipitation, EOF, Spatial Variability, Interannual Variability

Ahmad, I. , Ambreen, R. , Sun, Z. and Deng, W. (2015) Winter-Spring Precipitation Variability in Pakistan. American Journal of Climate Change, 4, 115-139. doi: 10.4236/ajcc.2015.41010.