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Titel |
Tomographic retrieval of cloud liquid water fields from a single scanning microwave radiometer aboard a moving platform – Part 2: Observation system simulation experiments |
VerfasserIn |
D. Huang, A. Gasiewski, W. Wiscombe |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1680-7316
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Digitales Dokument |
URL |
Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 14 ; Nr. 10, no. 14 (2010-07-22), S.6699-6709 |
Datensatznummer |
250008647
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Publikation (Nr.) |
copernicus.org/acp-10-6699-2010.pdf |
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Zusammenfassung |
Part 1 of this research concluded that many conditions of the 2003 Wakasa
Bay experiment were not optimal for the purpose of tomographic retrieval.
Part 2 (this paper) then aims to find possible improvements to the mobile
cloud tomography method using observation system simulation experiments. We
demonstrate that the incorporation of the L1 norm total variation
regularization in the tomographic retrieval algorithm better reproduces
discontinuous structures than the widely used L2 norm Tikhonov
regularization. The simulation experiments reveal that a typical
ground-based mobile setup substantially outperforms an airborne one because
the ground-based setup usually moves slower and has greater contrast in
microwave brightness between clouds and the background. It is shown that, as
expected, the error in the cloud tomography retrievals increases
monotonically with both the radiometer noise level and the uncertainty in
the estimate of background brightness temperature. It is also revealed that
a lower speed of platform motion or a faster scanning radiometer results in
more scan cycles and more overlap between the swaths of successive scan
cycles, both of which help to improve the retrieval accuracy. The last
factor examined is aircraft height. It is found that the optimal aircraft
height is 0.5 to 1.0 km above the cloud top. To summarize, this research
demonstrates the feasibility of tomographically retrieving the spatial
structure of cloud liquid water using current microwave radiometric
technology and provides several general guidelines to improve future
field-based studies of cloud tomography. |
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