Spatiotemporal Trends and Anomalies of Surface Air Temperature
over the Punjab, Pakistan: Its Impacts and Consequences

Safdar Ali Shirazi

Department of Geography, University of the Punjab, Lahore, Pakistan
e-mail: shirazi@geog.pu.edu.pk

Abstract

Surface air temperature is one of the principal climatic elements influencing significantly to man and his environment. The monitoring and analysis of surface air temperature on global and regional scales has acquired special importance in the last few decades owing to the clear indications of global warming in the post-industrial era and its role in drought producing conditions . This is why attention has been focused on its anomalies in the present study. A fairly wide spread surface temperature observation network over Punjab is available for almost a century. However, owing to spatial and temporal inhomogeneity, the present research pertaining to spatial average temperature data have been used since 1973.Punjab is leading province in term of population and agriculture production. Most of the area comprises of level plain and all this area formed by the Indus and its tributaries. The plain extends from the foot of the hills in the northeast, north and west to the costal belt of the Arabian Sea in the south. The region as a whole is dry and hot in summer. The highest maximum temperatures in the country are generally recorded along the plain adjoining the western sub-mountain part. From March onwards temperatures begin to rise rapidly and hot weather prevails through the plain, till about the middle of June, when instability showers can be expected which temporarily bring the surface temperature down. The rise of temperature takes place in a series of heat waves of varying intensity. The climate of Punjab is continental with marked temperature fluctuations both seasonal and regional with significant aridity. The winter season starts in November and lasts till the end of March. January is the coldest month of season.   Thirty-year data were collected from Pakistan Meteorological Department of the six meteorological stations of Punjab to show the spatial as well as temporal variation in annual temperature from 1973-2003.For the sake analysis; Faisalabad, Sargodha, Multan, Bahawalpur, Sialkot and Lahore have been chosen to present temperature variability in the Punjab. Analysis has been carried out for annual mean maximum and mean minimum temperature by using statistical methods (arithmetic mean). All parameters are mean monthly observations of temperature recorded at six selected stations of the province. The annual trend series from 1973 to 2003 period have shown a good agreement with recent global and regional trends in temperature. Highest trend was found 0.21°C (mean maximum temperature) at Bahawalpur, which is located in the southern part of the Punjab and is situated almost in the center of the country. Highest trend (mean minimum temperature) has been noted as 0.64°C at Sargodha station. The study proves that the increase in temperature is primarily due to the increase in minimum temperature, thus the result revealed that the trend per decade in annual temperature is due to the significant increase in minimum temperature as compared to the maximum temperature. In this work, the authors have presented an analysis of observed surface-air temperature records over the Punjab-Pakistan during the last 30 years.