Abstract
Empirical Orthogonal Function (EOF) was performed to investigate spatial variation in January precipitation over Pakistan using ground observed mean monthly precipitation data from 1950-2000 with a combination of gridded reanalysis data of sea level pressure (SLP) and 500 hPa geopotential height. The leading EOF mode captures 37.51% of the total variance and the spatial-temporal variability of January precipitation was consistent in the study area. The temporal changes explicate non-periodic interannual variability and some tacit interdecadal variation. The anomalous condition is more prominent along the western bordering mountains and northern high mountainous region than any other region of Pakistan. Based on results the study reveals spatial-temporal variation in January precipitation and possible links with global teleconnections located both in the proximity as well as in the remote areas from the study locus.
Highlights
The Fourth Assessment Report of IPCC [1] projects that climate variability will further aggravate floods and droughts in Asia and will increase vulnerability of poor Asian community
Pakistan is located in subtropical region of south Asia with complex topography and has access to Western Disturbances (WDs), and this system of lows contributes to winter precipitation [7], further it is considered the second largest source of precipitation in Pakistan
The thermodynamic impact of mountains contributes to capturing precipitation [9] ; the western and northern parts of Pakistan receive maximum precipitation from WDs as they enter from the west associated with westerlies flow
Summary
The Fourth Assessment Report of IPCC [1] projects that climate variability will further aggravate floods and droughts in Asia and will increase vulnerability of poor Asian community. The year of 1997-98 was marked by strong El Nino Southern Oscillation (ENSO); induced five years drought from 1998-2002 in the south west Asia including Pakistan [4] [5] experienced most severe drought conditions in the last 50 years. As consequence, it triggered migration in different parts of southern Pakistan especially in Balochistan Province when meteorological drought reached the degree of hydrological drought. The thermodynamic impact of mountains contributes to capturing precipitation [9] ; the western and northern parts of Pakistan receive maximum precipitation from WDs as they enter from the west associated with westerlies flow. These vectors elucidate the maximum possible variance; the leading EOF has the potential to express maximum variance while the successive EOFs are counted for less variation respectively [12]
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