부산대학교 도서관

The launch of L-band passive microwave radiometer satellites in the last decade (SMOS, Aquarius, and SMAP) started a new era in Earth Observation at low frequency. On the trails of these missions, recent studies showed that microwave radiometers operating at even lower frequencies (P-band) can provide new information for cryospheric and ocean science and improve the current understanding of Earth processes. In particular, experimental airborne campaigns were conducted in both Artic and Antarctica, within the NASA's UWBRAD project, by using a wide band radiometer operating in the range 0.5-2 GHz, aimed at investigating the temperature profiles of ice sheets and the sea ice thickness. By leveraging the results of UWBRAD system, a new mission concept was proposed to ESA Earth Explorer 10 and 11 (called CryoRad) and NASA EVI-6 (called PolarRad) featuring a spacebome 0.4-2 GHz nadir-looking microwave radiometer for the monitoring of polar regions. Even though the main goals of all these sensors are related to observables such as soil moisture, ocean salinity, and geophysical parameters of the cryosphere, all of them suffer from the emission due the atmosphere. In the spectral range comprised between 0.5 and 2 GHz the atmosphere is considered almost transparent, being the major contributions to the emission due to the water vapor (in both physical phases) and to the molecular oxygen, however a clear assessment is still lacking in literature. The aim of this paper is to provide an accurate estimate of the atmospheric effect on measured T B from space at low frequency for different climate scenario by using a combination of in-situ data (i.e. radio-sounding) and microwave emission model.