Article ID Journal Published Year Pages File Type
4449653 Atmospheric Research 2016 16 Pages PDF
Abstract

•Tmax and Tmin trends in Pakistan are analysed at different time scales.•Relationships with four teleconnection patterns and temperatures are also studied.•Tmax and Tmin have increased in winter, pre-monsoon, and at annual resolution.•Highest correlations with patterns were found in the pre-monsoon season.

Data from 37 weather stations with records of maximum and minimum temperatures (Tmax and Tmin hereafter) were used to analyse trends in both variables at a monthly, seasonal and annual resolution. Sen's slope and Mann–Kendall statistical tests were applied to calculate the sign and slopes of trends and their statistical significance. A correlation analysis was also performed to study possible relationships between temperatures and certain teleconnection patterns with an influence on Northern Hemisphere temperatures: the North Atlantic Oscillation (NAO), Arctic Oscillation (AO), El Niño-Southern Oscillation (ENSO), and North Sea Caspian Pattern (NCP). The study reveals that Tmax has significantly increased (in over 30% of sites) in the pre-monsoon season and yearly. The sharpest increases were observed in March. Tmin clearly showed positive trends in the pre-monsoon season and at the annual scale. It is also worth noting a cooling trend in the northern areas during the study period. Tmax increased faster than Tmin in the northern areas in all the seasons studied and at annual resolution, while the opposite occurred in the rest of the country (except in the pre-monsoon season).The highest correlation coefficients between patterns and Tmax and Tmin were seen in the months of the pre-monsoon season: with NAO from January to March; with ENSO in May and with NCP in the late pre-monsoon season (May). AO was the pattern with the lowest relationships with temperatures. These results could have a significant influence on agriculture and water resources in Pakistan if these trends are maintained in the future.

Related Topics
Physical Sciences and Engineering Earth and Planetary Sciences Atmospheric Science
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