Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2017-422
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
14 Jun 2017
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Cloud climatologies from the InfraRed Sounders AIRS and IASI: Strengths, Weaknesses and Applications
Claudia J. Stubenrauch1,2, Artem G. Feofilov1,2, Sofia E. Protopapadaki1,2, and Raymond Armante1,2 1Laboratoire de Météorologie Dynamique / Institute Pierre-Simon Laplace, (LMD/IPSL), CNRS, Sorbonne Universities , University Pierre and Marie Curie (UPMC) Paris, University of Paris 06, Paris, France
2Laboratoire de Météorologie Dynamique / Institute Pierre-Simon Laplace, (LMD/IPSL), CNRS, Ecole Polytechnique, Université Paris-Saclay, Palaiseau, France
Abstract. The cloud retrieval scheme developed at the Laboratoire de Météorologie Dynamique (LMD) can now be easily adapted to any Infrared (IR) sounder: the CIRS (Clouds from IR Sounders) retrieval applies improved radiative transfer, as well as an original method accounting for atmospheric spectral transmissivity changes associated with CO2 concentration. The latter is essential when considering long-term time series of cloud properties. For the 13-year and 8-year global climatologies of cloud properties from observations of the Atmospheric IR Sounder (AIRS) and of the IR Atmospheric Interferometer (IASI), respectively, we used the latest ancillary data (atmospheric profiles, surface emissivities and atmospheric spectral transmissivities). The A-Train active instruments, lidar and radar of the CALIPSO and CloudSat missions, provide a unique opportunity to evaluate the retrieved AIRS cloud properties such as cloud amount and height as well as to explore the vertical structure of different cloud types. CIRS cloud detection agreement with CALIPSO-CloudSat is about 84%–85% over ocean, 79%–82% over land and 70%–73% over ice / snow, depending on atmospheric ancillary data. Global cloud amount has been estimated to 67%–70%. CIRS cloud height coincides with the middle between the cloud top and the apparent cloud base (real base for optically thin clouds or height at which the cloud reaches opacity) independent of cloud emissivity, which is about 1 km below cloud top for low-level clouds and about 1.5 km to 2.5 km below cloud top for high-level clouds, slightly increasing because the apparent vertical cloud extent is slightly larger for large cloud emissivity. IR sounders are in particular advantageous for the retrieval of upper tropospheric cloud properties, with a reliable cirrus identification down to an IR optical depth of 0.1, day and night. Total cloud amount consists of about 40% high-level clouds and about 40% low-level clouds and 20% mid-level clouds, the latter two only detected when not hidden by upper clouds. Upper tropospheric clouds are most abundant in the tropics, where high opaque clouds make out 7.5%, thick cirrus 27.5% and thin cirrus about 21.5% of all clouds. The asymmetry in upper tropospheric cloud amount between Northern and Southern hemisphere with annual mean of 5% has a pronounced seasonal cycle with a maximum of 25% in boreal summer, which can be linked to the shift of the ITCZ peak latitude. Comparing tropical geographical change patterns of high opaque clouds with that of thin cirrus as a function of changing tropical mean surface temperature indicates that their response to climate change may be quite different, with potential consequences on the atmospheric circulation.

Citation: Stubenrauch, C. J., Feofilov, A. G., Protopapadaki, S. E., and Armante, R.: Cloud climatologies from the InfraRed Sounders AIRS and IASI: Strengths, Weaknesses and Applications, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-422, in review, 2017.
Claudia J. Stubenrauch et al.
Claudia J. Stubenrauch et al.
Claudia J. Stubenrauch et al.

Viewed

Total article views: 212 (including HTML, PDF, and XML)

HTML PDF XML Total Supplement BibTeX EndNote
152 54 6 212 6 3 8

Views and downloads (calculated since 14 Jun 2017)

Cumulative views and downloads (calculated since 14 Jun 2017)

Viewed (geographical distribution)

Total article views: 212 (including HTML, PDF, and XML)

Thereof 210 with geography defined and 2 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 24 Jun 2017
Publications Copernicus
Download
Short summary
We present multi-year cloud climatologies from the advanced IR sounders AIRS and IASI. These data are particularly sensitive to cirrus. Cloud emissivity allows to distinguish between high opaque, thick cirrus and thin cirrus. By comparing tropical geographical change patterns of these cloud types with respect to changing tropical mean surface temperature, it is demonstrated that their response to climate change may be different, with potential consequences on the atmospheric circulation.
We present multi-year cloud climatologies from the advanced IR sounders AIRS and IASI. These...
Share