Calibration of a water vapour Raman lidar with a kite-based humidity sensor

Julien Totems (1, 2) , Patrick Chazette (1, 2)

1 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
2 CAE - Chimie Atmosphérique Expérimentale

We present a calibration method for a water vapour Raman lidar using a meteorological probe lifted by a kite, flown steadily above the lidar site, within the framework of the Hydrological Cycle in the Mediterranean Experiment (HyMeX) and Chemistry-Aerosol Mediterranean Experiment (ChArMEx) campaigns. The experiment was carried out in Menorca (Spain) during June 2013, using the mobile water vapour and aerosol lidar WALI. Calibration using a kite demonstrated a much better degree of co-location with the lidar system than that which could be achieved with radiosondes, and it allowed us to determine the overlap function and calibration factor simultaneously. The range-dependent water vapour lidar calibration was thus determined with an uncertainty of 2 % in the 90-8000 m altitude range. Lidar water vapour measurements are further compared with radiosondes, showing very good agreement in the lower troposphere (1-5 km) and a relative difference and standard deviation of 5 and 9 % respectively. Moreover, a reasonable agreement with MODIS-integrated water vapour content is found, with a relative mean and standard deviation of 3 and 16 % respectively. However, a discrepancy is found with AERONET retrievals, showing the latter to be underestimated by 28 %. Reanalyses by the ECMWF/IFS numerical weather prediction model also agree with the temporal evolution highlighted with the lidar, with no measurable drift in integrated water vapour content over the period.

Mots clés: ChArMEx

Domaines: Sciences de l'Homme et Société; Océan, Atmosphère; Interfaces continentales, environnement; Planète et Univers [physics]

Julien Totems, Patrick Chazette. Calibration of a water vapour Raman lidar with a kite-based humidity sensor. Atmospheric Measurement Techniques, 2016, 9 (3), pp.1083 - 1094. ⟨10.5194/amt-9-1083-2016⟩. ⟨hal-01587346⟩