Spatial–temporal variations of water vapor content over Ethiopia: a study using GPS observations and the ECMWF model

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• 作者：Kibrom Ebuy Abraha ; Elias Lewi ; Frédéric Masson ; Jean-Paul Boy&#8230
• 关键词：Ethiopia ; Water vapor ; GPS ; ECMWF
• 刊名：GPS Solutions
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：21
• 期：1
• 页码：89-99
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Geophysics/Geodesy; Atmospheric Sciences; Space Sciences (including Extraterrestrial Physics, Space Exploration and Astronautics); Automotive Engineering; Electrical Engineering;
• 出版者：Springer Berlin Heidelberg
• ISSN：1521-1886
• 卷排序：21

文摘

We characterize the spatial–temporal variability of integrated water vapor (IWV) in Ethiopia from a network of global positioning system (GPS) stations and the European Center for Medium range Weather Forecasting (ECMWF) model. The IWV computed from the ECMWF model is integrated from the height of the GPS stations on 60 pressure levels to take both the actual earth surface and the model orography discrepancies into account. First, we compare the IWV estimated from GPS and from the model. The bias varies from site to site, and the correlation coefficients between the two datasets exceed 0.85 at different time scales. The results of this study show that the general ECMWF IWV trend is underestimation over highlands and overestimation over lowlands for wet periods, and overestimation over highlands and underestimation over lowlands for dry periods with very few exceptional stations. Second, we observe the spatial variation of the IWV. High values are obtained in those stations that are located in the north-eastern (Afar depression) sites and the south-western part of the country. This distribution is related to the spatial variability of the climate in Ethiopia. Finally, we study the seasonal cycle and inter-annual variability of IWV for all stations over Ethiopia. The main result is the strong inter-annual variability observed for the dry seasons.