A reassessment of the discrepancies in the annual variation of δD-H2O in the tropical lower stratosphere between the MIPAS and ACE-FTS satellite data sets
Artikel i vetenskaplig tidskrift, 2020

The annual variation of δD in the tropical lower stratosphere is a critical indicator for the relative importance of different processes contributing to the transport of water vapour through the cold tropical tropopause region into the stratosphere. Distinct observational discrepancies of the δD annual variation were visible in the works of Steinwagner et al. (2010) and Randel et al. (2012). Steinwagner et al. (2010) analysed MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) observations retrieved with the IMK/IAA (Institut für Meteorologie und Klimaforschung in Karlsruhe, Germany, in collaboration with the Instituto de Astrofísica de Andalucía in Granada, Spain) processor, while Randel et al. (2012) focused on ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) observations. Here we reassess the discrepancies based on newer MIPAS (IMK/IAA) and ACE-FTS data sets, also showing for completeness results from SMR (Sub-Millimetre Radiometer) observations and a ECHAM/MESSy (European Centre for Medium-Range Weather Forecasts Hamburg and Modular Earth Submodel System) Atmospheric Chemistry (EMAC) simulation (Eichinger et al., 2015b). Similar to the old analyses, the MIPAS data set yields a pronounced annual variation (maximum about 75 ‰), while that derived from the ACE-FTS data set is rather weak (maximum about 25 ‰). While all data sets exhibit the phase progression typical for the tape recorder, the annual maximum in the ACE-FTS data set precedes that in the MIPAS data set by 2 to 3 months. We critically consider several possible reasons for the observed discrepancies, focusing primarily on the MIPAS data set. We show that the δD annual variation in the MIPAS data up to an altitude of 40 hPa is substantially impacted by a “start altitude effect”, i.e. dependency between the lowermost altitude where MIPAS retrievals are possible and retrieved data at higher altitudes. In itself this effect does not explain the differences with the ACE-FTS data. In addition, there is a mismatch in the vertical resolution of the MIPAS HDO and H2O data (being consistently better for HDO), which actually results in an artificial tape-recorder-like signal in δD. Considering these MIPAS characteristics largely removes any discrepancies between the MIPAS and ACE-FTS data sets and shows that the MIPAS data are consistent with a δD tape recorder signal with an amplitude of about 25 ‰ in the lowermost stratosphere.


Stefan Lossow

Karlsruher Institut für Technologie (KIT)

Charlotta Högberg

Stockholms universitet

F. Khosrawi

Karlsruher Institut für Technologie (KIT)

Gabriele P Stiller

Karlsruher Institut für Technologie (KIT)

Ralf Bauer

University of Toronto

Kaley A Walker

University of Toronto

S. Kellmann

Karlsruher Institut für Technologie (KIT)

A. Linden

Karlsruher Institut für Technologie (KIT)

M. Kiefer

Karlsruher Institut für Technologie (KIT)

N. Glatthor

Karlsruher Institut für Technologie (KIT)

T. von Clarmann

Karlsruher Institut für Technologie (KIT)

Donal Murtagh

Chalmers, Rymd-, geo- och miljövetenskap, Mikrovågs- och optisk fjärranalys

J. Steinwagner


T. Röckmann

Institute for Marine and Atmospheric Research, Utrecht

Roland Eichinger

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

Ludwig-Maximilians-Universität München (LMU)

Atmospheric Measurement Techniques

1867-1381 (ISSN) 1867-8548 (eISSN)

Vol. 13 1 287-308


Meteorologi och atmosfärforskning


Multidisciplinär geovetenskap



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