Estimation of the effective ice content on earth-satellite paths from dual-polarisation measurements at Ka-band

The paper presents a technique to estimate the instantaneous effective ice content (IC) in clouds from measurements of the differential propagation ch aracteristics of the earth-satellite transmission channel. High concentrati ons of ice crystals possessing a significant degree of common orientation h ave their habitat near the top of some types of clouds. They can induce imp ortant degradation of the crosspolar discrimination (XPD) on earth-satellit e links. The ice content is a fundamental parameter of models designed to c ompute XPD due to atmospheric ice crystals, and to the authors' knowledge, time series of IC have not yet been published. As a part of the technique f or estimating IC, a procedure for separating the contributions of rain and ice to depolarisation is proposed. Results obtained by applying the techniq ue to data recorded during the Olympus satellite propagation campaign are p resented. The estimates are in good agreement with values derived from rada r measurements. Finally, the values of IC retrieved from recordings at 20GH z are used to simulate XPD at 12,5GHz, resulting in very good agreement wit h measurements.