Evaluation of atmospheric precipitable water vapour distribution and trend over India

• Published in: Theoretical and applied climatology 2024-08, Vol.155 (8), p.8361-8377
• Main Authors: Tomar, Chander Singh, Bhatla, Rajeev, Singh, Nand Lal, Kumar, Vivek, Rai, Pradeep Kumar, Soni, Vijay Kumar, Giri, Ram Kumar
• Format: Article
• Language: English
• Subjects: Air temperature; Annual precipitation; Annual rainfall; Aquatic Pollution; Atmosphere; Atmospheric processes; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Climate system; Climatology; Correlation coefficient; Correlation coefficients; Earth and Environmental Science; Earth Sciences; Equatorial regions; Geographical distribution; Global navigation satellite system; Hydrologic cycle; Hydrological cycle; Medium-range forecasting; Monsoons; Navigation; Navigation satellites; Navigation systems; Navigational satellites; Precipitable water; Precipitation; Radiosondes; Rainfall; Root-mean-square errors; Satellite observation; Satellites; Seasonal variation; Seasonal variations; Seasons; Spatiotemporal data; Surface temperature; Surface-air temperature relationships; Temporal variability; Temporal variations; Trends; Waste Water Technology; Water Management; Water Pollution Control; Water vapor; Water vapor distribution; Water vapour; Weather forecasting; Wind; Winter
• ISSN: 0177-798X; 1434-4483
• DOI: 10.1007/s00704-024-05110-6

Integrated Precipitable Water Vapor (IPWV) wields significant influence over atmospheric processes, the climate system, and the hydrological cycle. Spatial and temporal variability characterizes water vapor distribution in the atmosphere, with equatorial regions registering elevated water vapor percentages. There are various types of instruments and methods to assess the quantity of moisture in the air. Global Navigation Satellite System (GNSS) and radiosonde techniques have been widely used to estimate IPWV in the atmosphere. European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-5) is the latest reanalysis IPWV dataset. This study aims to assess the congruence of ERA-5-derived IPWV with GNSS-derived IPWV and study the spatial and temporal variability of IPWV over Indian region. The IPWV data from 16 monitoring stations of GNSS Atmosphere Water Vapor Watch Network of the India Meteorological Department (IMD) have been compared with ERA-5 data. The IPWV data from GNSS and ERA-5 are in excellent agreement as corroborated by correlation coefficients spanning 0.97 to 1.00 and the Root Mean Square Error (RMSE) values varying between 1.5 mm and 5.6 mm. IPWV values exhibit prominent seasonal variations, with minimum values during the winter months and peak appears between June and September, aligning with warm and moist monsoon season of India. The ERA5 data from 1981 to 2020 were used to study variability and trend over Indian region. Strong positive correlations are observed between rainfall and IPWV. The results indicated IPWV trends are moistening especially over Indian landmass, the Indian Ocean, Arabian Sea and Bay of Bengal during all the seasons except winter. Highlights GNSS retrieved IPWV from 16 Indian stations used for comparison with ERA5 data. Strong agreement observed between ERA5 and GNSS IPWV data. Study examines correlation of IPWV with precipitation and surface air temperature. Study presents long term trend in IPWV and Rainfall. IPWV and rainfall positively correlated but have noteworthy geographic distribution characteristic. Annual mean rainfall and IPWV shows overall increasing trend over Indian subcontinent. Temperature and IPWV are negatively correlated for monsoon and pre-monsoon season.