Comparison of brightness temperatures observed from ground-based microwave radiometers during TUC

The agreement of two ground-based microwave radiometers during the Temperature, hUmidity, and Cloud (TUC) profiling campaign has been evaluated in terms of measured brightness temperature. To account effectively the instruments' specifications, we discuss and estimate an equivalent monochromatic frequency, which significantly reduces the bias introduced by ideal monochromatic modelling. The effect of this equivalent monochromatic frequency can reach 0.4 K and thus we recommend its use in further study involving TUC radiometers. This analysis showed agreement within expectations for three of the four selected pairs of channels, although results are strictly valid in a limited range. As a consequence, the derived products are expected to be of the same quality. However, the inconsistency found in the remaining pair is expected to propagate in the retrieved humidity profiles.