On the opportunistic use of geostationary satellite signals to estimate rain rate in the purpose of radar calibration

International audienceRain gauge networks are often used for radar calibration. However, the deployment of such networks is relatively complex and expensive. The present study deals with the development of a new low cost microwave device devoted to radar calibration. The principle of this device is to use rain atmospheric attenuation along microwave links to deduce the path averaged rain rate. In order to perform a feasibility study of such a device, a measurement campaign is performed for two years near Paris. Measurements of atmospheric attenuation over an earth-space link have been carried out by receiving TV channels from different geostationary satellites in Ku-band. These links are characterized by an aperture angle of 2° and a 30° elevation angle corresponding more or less to a 6 km path length through troposphere. The aim of this paper is to propose an algorithm to retrieve rain rate from the measured signal and to quantify the expected averaged rain rate accuracy along the earth-space link. In practice, the received signal is sensitive to rain as well as to many other fluctuations due to atmospheric scintillations, clouds, water vapor, small changes in the satellite orbit, power fluctuations