Predicting rainfall from IRNSS-retrieved precipitable water and surface meteorological elements

In this paper, the authors have investigated a few surface meteorological elements, namely surface temperature (ST), surface pressure (SP), relative humidity (RH), and the integrated precipitable water vapor (IPWV) to predict the occurrence of rainfall over a few locations in India, viz. Bhubaneswar, Gadanki, Goa, Kanakapura, and Kolkata. They have obtained the surface temperature, surface pressure, and relative humidity over these locations from the Integrated Global Radiosonde Archive (IGRA). They have estimated the precipitable water over these locations using the tropospheric slant delay (TSD) obtained from the Indian Regional Navigation Satellite System (IRNSS). The results show that it is possible to predict the onset of rainfall based on these meteorological elements. The study shows the maximum rainfall in a month mostly follows after the relative humidity reaches its maximum. The study also reveals that these meteorological elements show gradual variations when rainfall intensity varies from very low to extreme category. Besides, the investigation of the several pairs of rainy and non-rainy days reveals that these elements show peculiar characteristics that lead to rainfall. The geography and season influence the relationship between rainfall and surface meteorological elements. Besides, the mutual relationship between these elements also affects the relationship between rainfall and a particular element. The investigation shows that the integrated precipitable water depends on latitude, while the relative humidity increases as the proximity to the sea increases. The paper presents functional relationships of rainfall with surface temperature (ST), surface pressure (SP), relative humidity (RH), integrated precipitable water vapor (IPWV), and total solar irradiance (TSI).