On the Dynamic Variability of Global Positioning System (GPS) derived Precipitable Water Vapour (PWV) over three regions of Nepal

This study presents an attempt to derive Zenith Total Delay (ZTD) and Precipitable Water Vapour (PWV) from Global Positioning System (GPS) and observed meteorological data over three topological regions of Nepal: Terai, Hilly and Himalayan regions. Four months of the year 2015, each from four different seasons was taken as the study period and the obtained data were plotted and the trends were compared. The result showed that the average PWV is higher in the Terai region in comparison to the Hilly and Himalayan regions. This in turn explained the rainfall trends in Himalayan region of Nepal. The diurnal behaviour of PWV shows that it was highest during midday of the local time and was lowest during night.