Spatial variability of water vapour in south and southwest of Iran

Abstract

In this study two regression models, ordinary least square and geographically weighted regression as widely applied techniques, were used in modeling the regression relationships between water vapour and related geographic features, i.e., longitude, latitude, elevation, slope and aspect. Accordingly, the water vapour data in south and southwest of Iran were collected in pixels in the time interval 1981-2010. According to the general OLS regression, the relationship between WV and latitude, elevation and aspect were reverse and with longitude and slope were positive. Analyzing the relationship between geographic features and WV by GWR model determined that greatest coefficients of explanatory variables were in longitude, latitude, slope, aspect and elevation, respectively. Regarding to the model performance, GWR showed an improvement over OLS in estimating the WV and provided more realistic and useful results. So that the R², Adjusted R² and AICc for GWR were 0.967, 0.968 and 9329.38, respectively while these factors for OLS were 0.8478, 0.8475 and 14559.04.