Publications

Yadav, R; Giri, RK; Puviarasan, N; Bhan, SC (2022). Annual, seasonal, monthly & diurnal IPWV analysis and precipitation forecasting over the Indian subcontinent based on monthly thresholds of ground-based GNSS-IPWV. ADVANCES IN SPACE RESEARCH, 70(10), 3122-3136.

Abstract
In this study, diurnal, monthly, seasonal, and annual variations in the behavior of Integrated Precipitable Water Vapour (IPWV) were estimated from the ground-based Global Navigation Satellite System (GNSS) stations network of India Meteorological Department (IMD) over the Indian region from 2017 to 2020. It is noticed in the study that the availability of moisture for coastal, inland, and desert stations are different and mainly influenced by horizontal advection or deep convection (when it occurs) by local as well as global weather systems affecting throughout the year over Indian region. These changes are also reflected in GNSS IPWV retrievals and behave differently for inland, coastal and desert locations. The diurnal variation (maximum, minimum) shows that the minimum value of IPWV occurred almost the same time for inland (0000-0002 UTC), coastal (0002-0004 UTC) stations except for Dwarka (1500 UTC), and one dessert station Sri Ganganagar (1800 UTC) whereas the maximum value varying from 0800 to 1000 UTC at inland & desert stations except for Pune (1200 UTC) and coastal stations (0700-1500 UTC). The monthly variation of highest/lowest IPWV values occurred in June, July & August/December & January respectively for all the stations of the Indian region (>60 mm for inland & desert, and for coastal stations it ranges between 55 and 61 mm). The station-wise seasonal distributions are further grouped as high and low-value regions of IPWV for all the seasons. The value of the seasonal mean IPWV was observed highest in the monsoon season (June to August), followed by post-monsoon (September to November) and pre-monsoon (March to May), and winter (December to February). It is noticed that the stations situated in North India (Sri Ganganagar) registered the lowest values of IPWV in -all seasons, whereas the highest IPWV values are registered at the stations Jalpaiguri of the North East with 66.16 mm, Nagpur of Central India with 65.47 mm in monsoon season. The lowest values of the annual mean of IPWV were noticed at the inland stations in Sriganganagar (23.86 mm) and the highest ones at the stations on the Thiruvananthapuram (47.59 mm) on the west coast of India. This study will be useful to understand the relationship between precipitation and the IPWV up to some extent and helpful in operational forecasting by considering other parameters like combining background circulation, thermodynamic conditions, etc., especially during convective weather events. In this paper, 4 case studies (event-wise) are presented for New Delhi GNSS stations and statistical skill scores were calculated which agree reasonably well with the actual occurrence. All the rainfall correlated events of the year 2021 were analyzed based on the monthly threshold of IPWV and the correct rate & false alarm rate were observed as 86 % & 14 % for station Delhi and similarly 85% & 15% for station Jalpaiguri respectively. (C) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.

DOI:
10.1016/j.asr.2022.07.066

ISSN:
1879-1948