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The present work evaluates eleven existing empirical models to estimate Precipitable Water Vapor ( P W V ) over a high-altitude (4500 m amsl), cold-desert environment. These models are tested extensively and used globally to estimate P W V for low altitude sites (below 1000 m amsl). The moist parameters used in the model are: water vapor scale height ( H c ), dew point temperature ( T d ) and water vapor pressure ( E s 0 ). These moist parameters are derived from surface air temperature and relative humidity measured at high temporal resolution from automated weather station. The performance of these models are examined statistically with observed high-resolution GPS ( G P S P W V ) data over the region (2005–2012). The correlation coefficient (R) between the observed G P S P W V and Model P W V is 0.98 at daily data and varies diurnally from 0.93 to 0.97. Parameterization of moisture parameters were studied in-depth (i.e., 2 h to monthly time scales) using G P S P W V , T d , and E s 0 . The slope of the linear relationships between G P S P W V and T d varies from 0.073°C −1 to 0.106°C −1 (R: 0.83 to 0.97) while G P S P W V and E s 0 varied from 1.688 to 2.209 (R: 0.95 to 0.99) at daily, monthly and diurnal time scales. In addition, the moist parameters for the cold desert, high-altitude environment are examined in-depth at various time scales during 2005–2012. [ABSTRACT FROM AUTHOR]

Abstract: Water vapour plays a dominant role in the high-energy thermodynamics of the atmosphere, notably, the genesis of storm systems. However, its distribution is difficult to resolve by conventional means, since water vapour exhibits very high spatial and temporal variability. The growing networks of continuously operating GPS systems, however, offer the possibility of estimating the integrated water vapour (IWV) or, equivalently precipitable water vapour (PW). These estimates constitute critical inputs in operational weather forecasting and fundamental research to model atmospheric storm systems, atmospheric chemistry, and the hydrological cycle. This paper presents the results of IWV estimates from GPS data from continuously operating GPS stations established by C-MMACS at Bangalore, Kodaikanal, Hanle and Shillong over the 3-year period (2001–2003). These are the first results of such an endeavor, towards the study of PW at four different geographical locations in the Indian subcontinent. [Copyright &y& Elsevier]