Variability and Trends of Atmospheric Moisture over the Indian Region

In this chapter, we have examined humidity and surface soil moisture data over the Indian region for the period of 1969–2012 and analysed the variability and long-term trends. The analysis revealed that the all India averaged specific humidity is significantly increasing during all the seasons while relative humidity is increasing in all the seasons, except for the monsoon season. The magnitude of seasonal trends in specific humidity is the highest in summer where it is increasing at the rate +0.32 g/kg per decade and the lowest in monsoon season where the rate of increase is +0.20 g/kg per decade. The increase in surface humidity and atmospheric moisture content is consistent with the increase in surface air temperatures over India. The variations of annual surface soil moisture show general agreement with the observed changes in rainfall. Out of the 27 stations considered for the analysis, 15 stations are showing increasing trends in soil moisture.