Abstract
The Global Positioning System (GPS) is a space-based radio positioning system, which is capable of providing continuous position, velocity and time information to users anywhere on, or near, and the surface of the Earth. The main objective of this work was to estimate the integrated precipitable water vapour (IWV) using ground Global Positioning System (GPS) and Low Earth Orbit (LEO) Radio Occultation (RO) to study spatial-temporal variability. For LEO-GPS radio occultation, we used Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) datasets. We estimated daily and monthly mean of IWV using six selected ground GPS stations over a period of 2012 to 2016. We studied temporal, seasonal, diurnal, and vertical variations of precipitable water vapour using GPS observables extracted by precise geodetic GAMIT-GLOBK software package. Finally, we determined the cross-correlation of our GPS derived IWV values with those of the European Center for Medium-Range Weather Forecasts (CMWF) ERA-40 Interim reanalysis and of the second generation National Oceanic and Atmospheric Administration (NOAA) model ensemble Forecast System Reforecast (GEFS/R) for validation and static comparison. There are higher values of the IWV range from 30 to 37.5 millimeter (mm) in Gambela and Southern Regions of Ethiopia. Some parts of Tigray, Amhara and Oromia regions had low IWV ranges from 8.62 to 15.27 mm. The correlation coefficient between GPS derived IWV with EMWF and GEFS/R exceeds 90%. We conclude that there is highly temporal, seasonal, diurnal, and vertical variations of precipitable water vapour in the study area.
Presenters
Asmamaw YehunTeaching, Research, and Community Services, Institute of Land Administration, Bahir Dar University, Adis Abeba, Ethiopia
Details
Presentation Type
Paper Presentation in a Themed Session
Theme
KEYWORDS
GNSS, RADIO OCCULTATION, ATMOSPHERE, PRECIPITABLE WATER VAPOUR
