Global distributions of water vapour isotopologues retrieved from IMG/ADEOS data

Abstract

Abstract. The isotopologic composition of water vapour in the atmosphere provides valuable information on many climate, chemical and dynamical processes. The accurate measurements of the water isotopologues by remote-sensing techniques remains a challenge, due to the large spatial and temporal variations. Simultaneous profile retrievals of the main water isotopologues (i.e. H 16 2 O, H 18 2 O and HDO) and their ratios are presented here for the first time, along their retrieved global distributions. The results are obtained by exploiting the high resolution infrared spectra recorded by the Interferometric Monitor for Greenhouse gases (IMG) instrument, which has operated in the nadir geometry onboard the ADEOS satellite between 1996 and 1997. The retrievals are performed on cloud-free radiances, measured during ten days of April 1997, considering two atmospheric windows (1205-1228 cm −1 ; 2004-2032 cm −1 ) and using a line-by-line radiative transfer model and an inversion procedure based on the Optimal Estimation Method (OEM). Characterizations in terms of vertical sensitivity and error budget are provided. We show that a relatively high vertical resolution is achieved for H 16 2 O (∼4-5 km), and that the retrieved profiles are in fair agreement with local sonde measurements, at different latitudes. The retrieved global distributions of H 16 2 O, H 18 2 O, HDO and their ratios are presented and found to be consistent with previous experimental studies and models. The OceanContinent difference, the latitudinal and vertical dependence of the water vapour amount and the isotopologic depletion are notably well reproduced. Others trends, possibly related to small-scale variations in the vertical profiles are also discussed. Despite the difficulties encountered for computing Correspondence to: H. Herbin (hherbin@ulb.ac.be) accurately the isotopologic ratios, our results demonstrate the ability of infrared nadir sounding for monitoring atmospheric isotopologic water vapour distributions on a global scale.

Monitoring of atmospheric composition using the thermal infrared IASI/MetOp sounder

“…Coheur et al, 2007;Clerbaux et al, 2008a;, the nadir looking IMG/ADEOS sounder (e.g. Clerbaux et al, 2003;Coheur et al, 2005;Barret et al, 2005;Herbin et al, 2007), and the TES/AURA FTS (Clerbaux et al, 2008b).…”

Global-scale remote sensing of water isotopologues in the troposphere: representation of first-order isotope effects

“…In addition, global water isotopologue data have become available using remote sensing techniques installed onboard satellite platforms: the Interferometric Monitor for Greenhouse Gases (IMG) on ADEOS (Zakharov et al, 2004;Herbin et al, 2007), the Tropospheric Emission Spectrometer (TES) on Aura , the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat (Payne et al, 2007;Steinwagner et al, 2007Steinwagner et al, , 2010Lossow et al, 2011), the SCanning Imaging Absorption spectroMeter for Atmospheric CHartography (SCIA-MACHY) on Envisat (Frankenberg et al, 2009;Scheepmaker et al, 2013), the Infrared Atmospheric Sounding Interferometer (IASI) on Metop (Herbin et al, 2009;Lacour et al, 2012;Schneider and Hase, 2011;Wiegele et al, 2014), and the Greenhouse gases Observing SATellite (GOSAT) launched by the Japanese Space Agency in January 2009 (Boesch et al, 2013;Frankenberg et al, 2013). These instruments are sensitive to different parts of the atmosphere.…”

Estimate of bias in Aura TES HDO/H<sub>2</sub>O profiles from comparison of TES and in situ HDO/H<sub>2</sub>O measurements at the Mauna Loa observatory

“…Most validations of these data have therefore relied on indirect comparisons of the distributions of water vapor isotopes between satellite and aircraft (e.g. Webster and Heymsfield, 2003) or validation of the H 2 O measurements, which in turn can be used to assess the errors on the estimate of the HDO/H 2 O ratio (e.g., Worden et al, 2006;Herbin et al, 2007Herbin et al, , 2009). There are several currently operational sounders measuring the isotopic composition of water vapor such as the Tropospheric Emission Spectrometer (TES), the Atmospheric Chemistry Experiment (ACE), the Infrared Atmospheric Sounding Interferometer (IASI), the SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY), and the Greenhouse gases Observing SATellite (GOSAT), as well as several future satellites such as the IASI 2 and the Tropospheric Ozone Monitoring Instrument (TropOMI, http: //www.knmi.nl/samenw/tropomi/) that plan on measuring the isotopic composition of water vapor.…”