Retrieving Atmospheric Parameters from GroundBased Global Positioning System and Radio Occultation over Equatorial Regions for Improving Weather Prediction

Asmamaw, Chanie

dc.contributor.author	Asmamaw, Chanie
dc.date.accessioned	2021-10-21T06:37:08Z
dc.date.available	2021-10-21T06:37:08Z
dc.date.issued	2021-10-10
dc.identifier.uri	http://ir.bdu.edu.et/handle/123456789/12826
dc.description.abstract	Climate change and weather dynamic is the cross-cutting issue all over the world. For developing countries, especially, for East Saharan African countries including Ethiopia, the backbone of the economy depends on agriculture and accurate weather information is demanding. Most of the weather information is obtained from traditional surface meteorology stations. The weather information obtained from this station is not accurate enough, had recording bias, and had lacked in a digital data center. The main objective of this research is to estimate and retrieve atmospheric parameters such as precipitable water vapour (PWV) using ground-based GPS and remote sensing techniques such as GPS Radio Occultation (RO) for accurate weather studies and forecasting. The specific objective of this work was to estimate the regional vertical Total Electron Content (vTEC) densities, using a linear combination of L1 and L2 carrier phase for higher-order time delays at different thin-shell layers of the ionosphere over GPS stations in Ethiopia. Besides this, we estimate the GPS zenith delays to characterize the error of the neutral troposphere. During this research, we collected raw observational datasets using ground-based GPS from 2012 to 2015 and applied formula and modeling methodology. We process GPS observed data through GPS Analysis (GAMIT/GLOBK) software. From GPS RO, we retrieved bending angle, refractivity, temperature, pressure, and humidity profiles from Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 reanalysis and of the second generation National Oceanic and Atmospheric Administration (NOAA) model ensemble Forecast System Reforecast (GEFS/R) and Nevada Geodetic Laboratory Product (NGL). The longitudinal, latitudinal variations of the ionosphere and troposphere have been studied and reported by different scholars. Nevertheless, there is still a limitation regarding accurate estimation of the atmospheric parameters at different layers of the atmosphere. The merit of this work is that extension studies had been reviewed and we estimate the vTEC from five alternative layers of approximation through the ionospheric (i.e., 60, km, 90, km, 150, km, 200 km, and 450 km) to study ionosphere irregularities and estimate the precipitable water vapour from the GPS station up of the troposphere layers in order to study seasonal and vertica	en_US
dc.language.iso	en	en_US
dc.subject	Physics	en_US
dc.title	Retrieving Atmospheric Parameters from GroundBased Global Positioning System and Radio Occultation over Equatorial Regions for Improving Weather Prediction	en_US
dc.type	Thesis	en_US