CM SAF Passive Microwave Upper Tropospheric Humidity (UTH) Data Record - Edition 2

The second edition of the CM SAF Upper Tropospheric Humidity (UTH) is a satellite-based
climate data record. It is a near-global 1°x1° latitude-longitude dataset that is produced
with both hourly and daily time steps. The dataset is based on data from twelve passive
microwave (MW) sounders operating at 183 GHz in polar orbit that are combined into a single
time series covering the period 6 July 1994 to 31 December 2018. The UTH provided typically
represents a broad atmospheric layer between 500 and 200 hPa. However, the exact height of
this layer depends on the atmospheric conditions at the time of the observation. An optional
fixed layer approximation adjustment is supplied that users can apply to provide an estimated
mean relative humidity (RH) between ±60° latitude for a fixed layer between 500 and 200 hPa
(mean_RH). However, users are advised to take care using this correction, especially outside
of the tropics where the mean_RH is of lower quality. Users are also advised to take care
using UTH observations above ±60° latitude as the retrieval is sometimes less reliable at high
latitudes. Further information describing the dataset in detail can be found in the available
product documentation.