Analysis of the differences between GPS radio occultation and radiosonde atmosphere profiles in Egypt

Abstract

Difference values between Global Positioning System (GPS)-Radio Occultation (RO) and radiosonde (RS) profiles are analyzed to assess the integration applicability between them in Egypt. Compared profiles which have altitudes ranged from 3 to 25 km are used in analysis for ten years of RO and RS data. According to single profile comparison and t test, all difference values are not significant except for Water Vapor Pressure (WVP). Pressure, temperature, WVP and refractivity mean difference values are 0.6 mb, 0.79 deg, 0.1 mb, 0.48 with relative error of 0.3%, 1.7%, 62% and 0.7%, respectively however, refractivity values are significantly affected by small difference in the other parameters. According to Low Earth Orbiter (LEO) satellites difference analysis, GRACE2 gave maximum difference values of 4.3 ± 0.15 mb in pressure and 7.8 ± 0.35 deg in temperature with a relative error of 1.96% and 16.26% for them, respectively. COSMIC 3 & 6 and GRACE1 gave minimum difference values and the other missions gave small difference values but all of these differences are considered statistically significant. According to upper air stations difference analysis, station Benina gave big difference values of 5.1 ± 0.23 mb in pressure and 6 ± 0.3 deg in temperature with a relative error of 2.3% and 12.58% for them, respectively. Stations Mersa Matruh, Athalasa and South of Valley gave a smaller difference values and the other stations gave small difference values. However, all of stations differences are statistically significant.

Keywords

• Radio occultation
• GNSS
• Radiosonde