Pseudo-Monthly Raman Lidar Data Set for Referenced Water Vapor Observations in the UTLS Domain

Upper Tropsphere (UT) humidity records are crucial for climat studies.  Pseudo-monthly averaging is applied to maximize temporal representativeness, and enhance the lidar signal allowing to provide WVMR profiles up to 16 km. This study evaluates 11 years (2013–2023) of water vapor mixing ratio (WVMR) profiles from a UV Raman lidar (Lid1200) at the Reunion Island against MLS-Aura satellite retrieval, ERA5 reanalysis, and GRUAN-processed M10 radiosondes.  Results show a systematic dry bias in MLS of up to 30% above 12 km, particularly during the wet season. Lidar exhibits a small underestimates of WVMR around 5% drier than ERA5 all over the UT, with the largest deviations above 14 km, and larger variability during the wet season, Lidar calibration-related challenges during the dry season results in drier than ERA5 WVMR profiles (up to 10%). Aditionnaly, comparisons with GRUAN-processed radiosonde reveal a substantial lidar dry bias, exceeding 100% above 12 km.  Both lidar dry biases might be linked to the GNSS-based lidar calibration. Applying an alternative calibration method produces higher WVMR values, reducing the lidar dry bias w.r.t GRUAN by about 50% at upper-tropospheric levels, improving it's agreement with radiosondes, and revealing ERA5 dry bias increasing with altitude at the UT up to 25%. These efforts complement the global interest in the monitoring and validation of subtropical upper-tropospheric humidity.