Estimation of Atmospheric Liquid Water by Combined Observations From Ground-Based Single-Channel Microwave Radiometry and GNSS

Paper in proceeding, 2026

We combine a single-channel ground-based microwave radiometer (MWR), co-located with a GNSS receiving station, for estimating atmospheric integrated liquid water (ILW). Unlike the use of conventional dual-channel MWR systems, this approach exploits the substantially lower cost of single-channel radiometers together with the widespread availability of GNSS receivers, enabling a scalable observational framework. Challenges of single-channel radiometry is an absolute calibration and the separation of liquid water and water-vapour contributions to the observed sky brightness temperature. We address these limitations by using GNSS-derived estimates of atmospheric water vapour in two complementary ways. Periods with no liquid water content are used to calibrate the radiometer. During normal operation GNSS observations provide an independent estimate of the water-vapour contribution to the measured brightness temperature, replacing the second radiometric channel typically required for liquid water retrieval.