Variability trends in meteorological parameters at Ludhiana

Changes in meteorological parameters are of paramount importance in an agriculture based state like Punjab. The present study was undertaken to study the variability trends in meteorological parameters over the past four decades at Ludhiana. The maximum temperature has decreased from the normal during the month of January and June, but increased from normal during the months of February and March. The minimum temperature has however, increased from the normal at the rate of 0.04 – 0.07°C/year. The increasing trend in minimum temperature especially in the months of February and March over the past four decades is detrimental for wheat productivity as these two months correspond to grain filling stage of wheat in the state. The analysis of monthly maximum and minimum relative humidity revealed an increasing trend from the normal and the sunshine hours revealed a decreasing trend. Over the past two decades (1990–99 to 2000–09) the occurrence of temperature within 40–44°C range increased by 32 days and temperature >44°C increased by 9 days. During the four decades, the occurrence of extreme of minimum temperature <0°C was 9 days during 1970–79 followed by 6 days during 200009 and 1 day during 1980–89. An increase in number of rainy days was recorded from 1970–79 upto 1990–99 and thereafter during the recent decade (2000–09) a decrease (58 days) in rainy days was observed. The occurrence of extreme of rainfall (101-150mm) was 6 days during 1990–99 followed by 4 days during 1980–89 and 2000–09, and 1 day during 1970–79.