Cloud detection models and their effect on the calculation of cloud attenuation: Assessment at Ka-and Q-band at 4065 meters of altitude

This contribution presents a comparative study of methods to calculate cloud attenuation in satellite communications at 20 GHz and 40 GHz. A set of 3 years of radiosonde observations, collected at 4065 meters of altitude in the southern hemisphere, are used as input to four different cloud detection models, in order to retrieve integrated liquid water content, then calculate the attenuation due to clouds. The results are compared with those calculated using the ITU-R method based on ERA-40 NWP data. Based on the analysis performed at this particular site, located in an extensive high altitude Andean region in Bolivia, the results given by the ITU-R ERA-40 model seems to approximate better to the estimates obtained with cloud detection models other than the Salonen model, which is commonly accepted in temperate and lower altitude regions. However, in absolute values, the differences are less noticeable at 20 GHz than at 40 GHz.