A Study on Wet Tropospheric Delay Error Estimation for the Navigation Signals over Indian Region

The present work deals with the wet tropospheric delay estimation using the different models for navigation signals over the Indian region. Results from various mathematical models are analysed for saturation vapour pressure, partial vapour pressure, and wet delay estimation. The delay is estimated for four places in India which are spread at different geographical locations. It is observed that the Wexeler model is more suitable for saturation vapour estimation. It shows that the difference between 0.00 to 0.25 mb with reference values throughout the year. Saturation vapour pressure which is derived using the Wexeler model is further used for partial vapour pressure estimation. Four different models were used to estimate partial vapour pressure and Zyuring model is found more suitable among all. The partial vapour pressure values vary from 5 mb to 25 mb at different altitudes. The results of the Zyuring model is further used to derive wet tropospheric delay. It is found that Hopfield model provides difference of up to 4 mm in tropospheric delay, better than any other seven models results which are used for wet delay estimation. Tropospheric wet delay is observed more in daytime as compared to nighttime. From the analysis, it is found that the Hopfield model is more suitable for wet delay estimation and can be used for wet delay corrections in navigation signals for accurate position estimation.