Year-end Sale % OFF 
Abstract
Atmospheric water vapor plays a crucial role in atmospheric, climate change, meteorological, and hydrological processes. In a country like Ethiopia, with its complex topography and synoptic-scale spatiotemporal circulation patterns, the analysis of the spatiotemporal variability of precipitable water vapor (PWV) is very challenging, and is hampered by the lack of long observational datasets. In this study, we process the PWV over eight Ethiopian global positioning system (GPS) sites and one close to the Ethiopian eastern border, for the available common period 2013–2020, and compare with the PWV retrieved from the state-of-the-art ERA5 reanalysis. Both PWV datasets agree very well at our sample, with correlation coefficients between 0.96 and 0.99, GPS-PWV show a moderate wet bias compared to ERA5-PWV for the majority of the sites, and an overall root mean square error of 3.4 mm. Seasonal and diurnal cycles are also well captured by these datasets. The seasonal variations of PWV and precipitation at the sites agree very well. Maximum diurnal PWV amplitudes are observed for stations near water bodies or dense vegetation, such as Arbaminch (ARMI) and Bahir Dar (BDMT). At those stations, the PWV behavior at heavy rainfall events has been investigated and an average 25% increase (resp. decrease) from 12 h before (resp. 12 h after) the start of the rainfall event, when the PWV peaks, has been observed.
Highlights
Accepted: 29 January 2022Water vapor is a very important constituent of the atmosphere, as it contributes strongly to the atmospheric energy budget by transporting moisture and energy as latent heat through the troposphere and lower stratosphere
We address the following questions: (1) Are there potential systematic precipitable water vapor (PWV) biases that depend on the orography? (2) Does the increased spatial and temporal resolution of ERA5 with respect to its predecessor ERA-Interim amount to a closer agreement with global positioning system (GPS) in terms of the PWV seasonal and diurnal cycle? given the high spatial and temporal resolution of the GPS-PWV dataset, we explore a potential relationship between GPS-PWV and severe rainfall events at two Ethiopian sites in areas that are sensitive to flooding
The results show a good agreement with biases between GNSS at Massachusetts Institute of Technology (GAMIT)-zenith total delay (ZTD) and International GNSS Service (IGS)-ZTD ranging from −2.76 mm to 1.83 mm (IGS-ZTD taken as reference), root mean square error (RMSE) ranging from 2.46 mm to
Summary
Water vapor is a very important constituent of the atmosphere, as it contributes strongly to the atmospheric energy budget by transporting moisture and energy as latent heat through the troposphere and lower stratosphere. Our study differs from previous PWV comparisons at Ethiopia involving GPS by the considered time period (2007–2011 in [24,25]), the used subset of Ethiopian GPS sites [24,25,27], and the use of previous versions of ECMWF reanalysis models in [24,25,27]. Those analyses concluded that the GPS PWV had a dry bias compared to ERA-Interim [28] over Ethiopian lowlands, and a wet bias over the highlands.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
