A lightweight balloon-borne mid-infrared hygrometer to probe the middle atmosphere: Pico-Light H₂O. Comparison with Aura-MLS v4 and v5 satellite measurements

Abstract. Newly developed mid-infrared lightweight hygrometer, Pico-Light H₂O has been tested in-flight on February 19, 2019 and October 16, 2019. It has been flown under a 1200 g rubber balloon operated by CNES from the Aire-sur-l'Adour facility (France) within the E.U. funded HEMERA WP11. During these two flights, we were able to obtain coincident MLS v4 and v5 water vapor and temperature profiles, leading to an inter-comparison between Pico-Light and Aura-MLS water vapor and temperature retrievals. Results from the comparison are in line with previous reported studies . Here, differences in the mid-latitude stratosphere and upper troposphere (20–316 hPa) are within 7 % and 64 % respectively. Largest differences with MLS v4 occurring within the upper troposphere nearby the cold point tropopause. The v5 MLS data have been corrected for observed dry bias nearby the tropopause, allowing to partially solve the observed discrepancies. Additionally, on February 19, the hygrometer has flown within an air filament from polar latitudes most of the flight for which a signature is observed on the water vapor profile and confirmed with ozone reanalysis from ERA 5and potential vorticity from MIMOSA advection model.