Weighted mean temperature model for extra tropical region of India

•No unique weighted mean temperature (Tm) model is available for extra tropical region of India.•We developed site-specific and regional Tm model based on surface temperature.•The site-specific and regional Tm model predicts PWV with sub mm accuracy.•The site-specific Tm model is slightly better than the regional and global model.

The Global Positioning System (GPS) estimates Precipitable Water Vapor (PWV) from Zenith Wet Delay (ZWD) using a key parameter called water vapor weighted mean temperature (Tm) of the atmosphere. However, Tm must be tuned to the specific area and location. Therefore, for estimation of PWV using GPS within the region covered between New Delhi and Srinagar, site specific as well as a regional Tm model has been developed as a function of surface temperature using six years radiosonde data. The result shows that the root mean square error (rmse) of the developed site-specific Tm model is about 3.5 °K at New Delhi and Patiala. However, the rmse of the developed site-specific Tm model at Srinagar is in the range of 4–5.5 °K. It has been found that the site specific Tm model is slightly (0.1–0.5 °K) better than the developed regional Tm model at New Delhi and Patiala, however, the error is more at Srinagar. It finds that the site-specific model is better than the regional and the global model in predicting PWV and provides sub mm accuracy within this region. However, the developed regional model provides the same level of accuracy in estimating PWV and more suitable for this region compared to other regional and global model. The GPS PWV has shown an accuracy of about 6.5 mm using site specific and regional Tm model and found comparatively better than other regional and global Tm model.