Surface-based microwave signature studies from 2 to 100 GHz were carried out over several years to provide empirical emissivity information for typical surface classes. The surface emissivity e_ρ (polarisation p) was determined from the effective object temperature T_eff, the brightness temperatures T_p of the object under investigation and of the downwelling sky radiation, T_sky in the relevant direction, using the relationship e_p = (T_p - T_sky)/(T_eff - T_sky), ranging from 0 to 1. The data presented here are based on measurements made with the PAMIR system operating at 4.9, 10.4, 21, 35 and 94 GHz and with a set of newer portable radiometers at 11, 21, 35, 48 and 94 GHz. Additional experiments - not reported here - were made with the RASAM instrument, a combined radiometer and scatterometer, operating over the frequency range from 2 to 12 GHz. Data collected with this instrument are reported in a separate catalogue which was described by Wegmuller et al. (1994).

Inspec keywords: remote sensing; atmospheric measuring apparatus; emissivity; atmospheric radiation; microwave measurement; brightness; radiometry

Other keywords: polarisation; portable radiometers; downwelling sky radiation; scatterometer; frequency 2 GHz to 100 GHz; RASAM instrument; surface emissivity data; microwave experiments; PAMIR system; brightness temperatures; effective object temperature; University of Bern

Subjects: Sunlight and atmospheric radiation