On variations of the decadal precipitable water vapor (PWV) over Turkey

Abstract

Water in all of its forms takes part nearly in all meteorological activities. Therefore, in climate and atmospheric studies, water vapor plays a central role. Precipitable Water Vapor (PWV) is hard to obtain since its distribution in the troposphere is heterogeneous and anisotropic. Radiosonde observations provide data for mapping the PWV for local to regional scale at low spatial and temporal resolution. Global Positioning System (GPS) provides an alternative option for gathering high temporal and spatial resolution PWV data. In this paper, seasonal PWV variations are studied. Data from six Turkish radiosonde stations were used to validate the performance of GPS estimated PWV. The computed root mean square error (RMSE) of PWV differences between GPS and radiosonde stations is about 1.40–1.82 mm. After assessing the performance of GPS estimated PWV, trends and seasonal variations are computed from a decade worth of 90 GPS stations in Turkey (Jan. 2010–Dec. 2019). These trends at GPS stations were validated using the Mann-Kendall trend test. The test suggests that the trends are statistically significant for all the stations. It has been found that the distinct seasonal cycles are in summer with a maximum water vapor and in winter with a minimum water vapor. The higher amplitudes are located in higher latitudes and lower latitudes (9–15 ± 0.1 mm), and at middle latitudes, amplitudes are considerably lower with 5–7 ± 0.1 mm.