Investigating the possible causes of climate change in India with satellite measurements

Abstract

India's climate is changing gradually from one year to another. A significant increase in surface air temperature in different Indian regions was observed from 1998 onwards, which became all the more pronounced in 2009. Monthly mean maximum and minimum temperatures were higher than normal values over the whole of India, accompanied by a sharp increase in the duration and frequency of hot days and heatwave conditions. In the light of these observations the paper is aimed at investigating the spatial and temporal variation of air temperature at different altitudes and the interannual trend for different months over the Indian region for a period of 108 years from 1901 to 2008. It is observed that the variation in air temperature is not uniform at all places in India. The yearly mean air temperature for the period 1948–2008 exhibits an increasing trend at all atmospheric layers from the surface up to 10 km. The recently observed increase in surface air temperature and longer periods of heatwaves and hot days in India may be due to a higher occurrence of dust storms and forest fires and the influence of local factors, such as a sharp population growth accompanied by uncontrolled urbanization and rapid industrialization, resulting in high levels of pollution and imbalances in the regional climate.

Acknowledgements

The author thanks Dr K. Krishna Kumar and his colleagues from IITM, Pune for providing the map of temperature homogeneous regions of India and the Indian regional monthly surface air temperature data set; NDC Pune, for providing the figure of annual mean temperature anomalies for the period 1901–2008; MODIS mission scientists and associated NASA personnel for the production of the data used in this research; and Prof. J. N. Goswami, Director of the Physical Research Laboratory, Ahmedabad, for providing library facilities. The air temperatures at different pressure levels were obtained from the website www.cdc.noaa.gov. Analyses and visualizations for dust, sulfate, black carbon AOD and atmospheric water vapour from MODIS and the UV aerosol index obtained from EP-TOMS/Aura OMI used in this paper were produced with the Giovanni online data system, developed and maintained by the NASA GES DISC. The variation in population of India since 1901 (table 1) and the population density map of India were obtained from the website www.censusindia.net. The map depicting the forest cover of India (figure 2) was obtained from the Forest Survey of India, Dehradun. Fire count data from ATSR World Fire Atlas has been taken from Ionia products of European Space Agency.