Impact of single-point GPS integrated water vapor estimates on short-range WRF model forecasts over southern India

• Published in: Theoretical and applied climatology Vol. 130; no. 3-4; pp. 755 - 760
• Main Authors: Kumar, Prashant, Gopalan, Kaushik, Shukla, Bipasha Paul, Shyam, Abhineet
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.11.2017; Springer; Springer Nature B.V
• Subjects: Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Climate models; Climate science; Climatology; Data; Data assimilation; Data collection; Earth and Environmental Science; Earth Sciences; Global navigation satellite system; Global Positioning System; Global positioning systems; GPS; Initial conditions; Meteorological research; Monsoons; Navigation; Navigation satellites; Numerical weather prediction; Original Paper; Positioning systems; Predictions; Rain; Rainfall; Rainfall forecasting; Satellite navigation systems; Satellites; Satellites (Spacecraft); Surface temperature; Waste Water Technology; Water Management; Water Pollution Control; Water vapor; Water vapour; Weather forecasting; Winter monsoon; India; Global Navigation Satellite System; Tropical Rainfall Measuring Mission; Global Position System; Root Mean Square Difference
• ISSN: 0177-798X; 1434-4483
• DOI: 10.1007/s00704-016-1894-7

Specifying physically consistent and accurate initial conditions is one of the major challenges of numerical weather prediction (NWP) models. In this study, ground-based global positioning system (GPS) integrated water vapor (IWV) measurements available from the International Global Navigation Satellite Systems (GNSS) Service (IGS) station in Bangalore, India, are used to assess the impact of GPS data on NWP model forecasts over southern India. Two experiments are performed with and without assimilation of GPS-retrieved IWV observations during the Indian winter monsoon period (November–December, 2012) using a four-dimensional variational (4D-Var) data assimilation method. Assimilation of GPS data improved the model IWV analysis as well as the subsequent forecasts. There is a positive impact of ∼10 % over Bangalore and nearby regions. The Weather Research and Forecasting (WRF) model-predicted 24-h surface temperature forecasts have also improved when compared with observations. Small but significant improvements were found in the rainfall forecasts compared to control experiments.