Calibration and use of microwave radiometers in multiple-site EM wave propagation experiments

The key role of microwave radiometers (MWRs) in electromagnetic (EM) wave propagation experiments is discussed in this contribution. Specifically, starting from the propagation data collected in two Italian sites (Spino d'Adda and Milan) in the frame of the Alphasat “Aldo Paraboni” propagation experiment, brightness temperature data are processed to derive the reference attenuation level in non-rainy conditions and, in combination with the beacon power levels received at 19.7 and 39.4 GHz, to derive total tropospheric attenuation A in any condition. Moreover, we evaluate to what extent and with what accuracy MWRs can reliably predict A also during rain events, when no beacon measurements are available. As expected, results indicate that the MWR accuracy decreases as the attenuation level increases, but also point out that the MWR performance depends on the choice of the radiometric channels used to estimate A.