Balloon-borne observations of mid-latitude stratospheric water vapour: comparisons with HALOE and MLS satellite data

Gwenaël Berthet (1) , Jean-Baptiste Renard (1) , Mélanie Ghysels (2) , Georges Durry (3) , Bertrand Gaubicher (1) , Nadir Amarouche (4)

1 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
2 Chemical Science and Technology Laboratory
3 GSMA - Groupe de spectrométrie moléculaire et atmosphérique
4 DTI - Division technique INSU/SDU

We present here in situ measurements obtained between 1991 and 2011 in outervortex conditions by the ELHYSA balloon-borne frost-point hygrometer. The frost-point hygrometer profiles are used for comparisons with the satellite data from version 19 (v19) and version 3.3 (v3.3) of the HALogen Occultation Experiment (HALOE) and theMicrowave Limb Sounder (MLS) respectively. Potential Vorticity mapping is applied to all data sets to remove contributions of transient tropical intrusions and polar vortex air masses and hence ensure consistent comparisons between the balloon and satellite observations. Our selected balloon in situ observations are too sparse to directly infer mid-latitude stratospheric time series for continuous comparisons with HALOE and MLS records or derive water vapour trends but can be used to validate the satellite data. A mean difference of −0.83±1.58 % (−0.04±0.07 ppmv) is obtained between HALOE v19 data and the balloon frost-point observations (with respect to HALOE) over the 30–80 hPa altitude range. The hygrometer-HALOE differences appear timedependent as already presented in the literature. The mean difference reaches 2.80±0.96 % (0.13±0.04 ppmv) forMLS v3.3,withMLS systematically wetter than the balloon data reflecting a systematic bias between both datasets. We use our balloon data as reference to provide some information about the HALOE-MLS difference. From post-2000 ELHYSA-HALOE and ELHYSA-MLS comparisons, we find a HALOE-MLS difference matching the expected bias, with MLS v3.3 6.60±2.80 % (0.27±0.11 ppmv) wetter than HALOE v19. From the results obtained from our balloon-satellite data comparisons, we finally discuss the issue about merging the HALOE and MLS data sets to provide stratospheric water vapour trends.

Keywords: Stratospheric water vapour; In situ balloon-borne measurements; Satellite validation; Frost-point hygrometer

Domains: Sciences of the Universe [physics]

Gwenaël Berthet, Jean-Baptiste Renard, Mélanie Ghysels, Georges Durry, Bertrand Gaubicher, et al.. Balloon-borne observations of mid-latitude stratospheric water vapour: comparisons with HALOE and MLS satellite data. Journal of Atmospheric Chemistry, 2013, 70, pp.197 - 219. ⟨10.1007/s10874-013-9264-7⟩. ⟨insu-01110062⟩