Remote sensing of atmospheric liquid water and water vapor with a dual-frequency radiometer

Liquid water and water vapor are important components for many meteorological processes in the atmosphere. For radio communication links on Earth-satellite paths they may cause attenuations which can no longer be neglected for frequencies above 10 GHz and thus have a strong impact e.g. on low-margin systems. Unfortunately, there is a lack of information on quantities like cloud liquid and its temporal and spatial variability. In the past, it was shown that the liquid water content in clouds as well as the ubiquitous water vapor can be determined from radiometer measurements carried out simultaneously at two different frequencies at least. However, statistics are only available for short time periods. The authors discuss the capabilities of radiometer systems operating at 21.3 and 31.7 GHz. Data obtained over a 24 month period are also presented.<>