Journal article
Retrieval of macrophysical cloud parameters from MIPAS: algorithm description
- Abstract:
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The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard ENVISAT has the potential to be particularly useful for studying high, thin clouds, which have been difficult to observe in the past. This paper details the development, implementation and testing of an optimal-estimation-type retrieval for three macrophysical cloud parameters (cloud top height, cloud top temperature and cloud extinction coefficient) from infrared spectra measured by MIPAS. A preliminary estimation of a parameterisation of the optical and geometrical filling of the measurement field-of-view by cloud is employed as the first step of the retrieval process to improve the choice of a priori for the macrophysical parameters themselves.
Preliminary application to single-scattering simulations indicates that the retrieval error stemming from uncertainties introduced by noise and by a priori variances in the retrieval process itself is small - although it should be noted that these retrieval errors do not include the significant errors stemming from the assumption of homogeneity and the non-scattering nature of the forward model. Such errors are preliminarily and qualitatively assessed here, and are likely to be the dominant error sources. The retrieval converges for 99% of input cases, although sometimes fails to converge for vetically-thin (< 1 km) clouds. The retrieval algorithm is applied to MIPAS data; the results of which are qualitatively compared with CALIPSO cloud top heights and PARASOL cloud opacities. From comparison with CALIPSO cloud products, it must be noted that the cloud detection method used in this algorithm appears to potentially misdetect stratospheric aerosol layers as cloud.
This algorithm has been adopted by the European Space Agency's "MIPclouds" project."
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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(Preview, Version of record, pdf, 2.8MB, Terms of use)
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- Publisher copy:
- 10.5194/amt-4-683-2011
- Publisher:
- Copernicus Publications
- Journal:
- Atmospheric Measurement Techniques More from this journal
- Volume:
- 4
- Issue:
- 4
- Pages:
- 683-704
- Publication date:
- 2011-04-01
- Edition:
- Publisher's version
- DOI:
- EISSN:
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1867-8548
- ISSN:
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1867-1381
- Language:
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English
- Subjects:
- UUID:
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uuid:cf98b0f0-9453-476f-b2e8-9de07fd21bbb
- Local pid:
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ora:5569
- Deposit date:
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2011-07-18
Terms of use
- Copyright holder:
- J Hurley, A Dudhia & R G Grainger
- Copyright date:
- 2011
- Notes:
- Citation: Hurley, J., Dudhia, A. & Grainger, R. G. (2011). 'Retrieval of macrophysical cloud parameters from MIPAS: algorithm description', Atmospheric Measurement Techniques, 4(4), 683-704. [Available at http://www.atmospheric-measurement-techniques.net/]. © Authors 2011. This article is distributed under the terms of the Creative Commons Attribution 3.0 Licence (http://creativecommons.org/licenses/by/3.0/). This permits the copying, distribution, transmission and adaption of the work, provided the original authors are credited. For any reuse or distribution, you must make clear to others the license terms of this work. These conditions may be waived if you get permission from the copyright holder.
- Licence:
- CC Attribution (CC BY)
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