Comparison of atmospheric humidity profiles obtained by COSMIC satellites and radiosonde over Cyprus

The determination of the atmospheric humidity profile has been traditionally conducted on a relatively local basis by ground-based radiosondes which are special types of instruments used for monitoring atmospheric parameters, such as temperature, humidity, wind and pressure at various altitudes in the atmosphere. An alternative modern technique for measuring atmospheric profiles is the GPS (Global Positioning System) Radio Occultation conducted by means of signals transmitted by GPS satellites (orbiting the Earth at ~ 20200 km) and received by LEO (Low Earth Orbit) satellites. The profiles based on this technique are inferred indirectly exploiting radio signals crossing the Earth’s troposphere and undergoing refraction. The FORMOSAT-3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) satellite constellation is such a system based on 6 satellites (at an orbit of ~ 800 km) and has been in operation since 2006 providing excellent spatial coverage with more than 2000 occultations per day. In this paper a comparison of the atmospheric humidity profiles over Cyprus is investigated in terms of these two different measurement techniques, within a period of six years.