Assessing the Monthly Trends in Precipitable Water Vapor Over the Indian Sub-Continent Using Reanalysis Data
Seema RANI, Dept. of Geography, Institute of Science, Banaras Hindu University, India
Pyarimohan MAHARANA, School of Ecology and Environment Studies, Nalanda University , India
Suraj MAL , Dept. of Geography, Shaheed Bhagat Singh College, University of Delhi, India
The present study aims to assess monthly trends in precipitable water vapor and the factors influencing it over the Indian sub-continent during 1980-2020. The study used examined variables like precipitable water vapor (PWV), air temperature, rainfall, cloud fraction (CF), cloud base height (CBH) and evapotranspiration (ET), convective available potential energy (CAPE), pressure velocity (Omega) and vertically integrated moisture flux and transport from ERA5 reanalysis datasets. Between 1000 and 300 hPa levels, the trend in PWV varies between -0.528 and 1.253 mm/decade in the region. It is significantly rising at a rate of 0.449 -0.100 mm/decade in the lower part of the atmosphere (1000-850 hPa). The spatial variation of the trend is highest for the zone 850-500 hPa (-0.445 - 0.825 mm/decade). Corresponding trend values of PWV vary from -0.022 to 0.230 mm/decade in 500-300 hPa. The changes in PWV may be attributed to changes in air temperature, rainfall, CF, CAPE, Omega CBH and ET. However, the study suggests the need to explore the effects of all these factors on PWV in detail with finer resolution data to improve the understanding of its spatial dynamics over the region. The study would be useful to improve the understanding of regional water-energy cycles along with the recent changes of the atmospheric dynamics influencing the recent changes.
Keywords: Precipitable water vapor|Climate change|Indian sub-continent|Sustainability