Changes in the Large-Scale Circulations Over North-West India

Abstract

The northwestern part of India occupies a vast landmass which roughly lies in the area bounded by 70.5°E–80.5°E longitudes and 27°N–37°N latitudes of South Asia. This is an important region of food-grain production in the country. The summer season (June to September) contributes about 75% of annual precipitation and the winter season from December to March 15–20%. These precipitations are very important for the crops and maintaining the western Himalayas Glaciers. The interannual variability of summer and winter precipitation are examined using observed and reanalysis datasets for the period of 1948–2015. The analysis shows changes in teleconnection pattern around the late-1970s, when the major ‘climate shift’ was observed in the Indo-Pacific Oceans. The summer precipitation teleconnection change is related to the change in the shape and position of the equatorial Pacific warming. And, the winter precipitation is mostly influenced by the two major weather phenomenon Arctic Oscillation/North Atlantic Oscillation (AO/NAO) and El-Niño–Southern Oscillation (ENSO), which exert strong control on the weather/climate of the Northern Hemisphere particularly in the boreal winter. The AO/NAO phenomenon were more influencing in the earlier decades, while the ENSO in the recent decades.