On the characteristics of ASCAT wind direction ambiguities
8 pages, 5 figures, 1 table The inversion of the Advanced Scatterometer (ASCAT) backscatter measurement triplets generally leads to two wind ambiguities with similar wind speed values and opposite wind directions. However, for up-, down- and crosswind (with respect to the mid-beam azimuth direction)...
| Published in: | Atmospheric Measurement Techniques |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
European Geosciences Union
2013
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| Subjects: | |
| Online Access: | http://hdl.handle.net/10261/75413 https://doi.org/10.5194/amt-6-1053-2013 |
| Summary: | 8 pages, 5 figures, 1 table The inversion of the Advanced Scatterometer (ASCAT) backscatter measurement triplets generally leads to two wind ambiguities with similar wind speed values and opposite wind directions. However, for up-, down- and crosswind (with respect to the mid-beam azimuth direction) cases, the inversion often leads to three or four wind solutions. In most of such cases, the inversion residuals or maximum likelihood estimators (MLEs) of the third and fourth solutions (i.e. high-rank solutions) are substantially higher than those of the first two (low-rank) ambiguities. This indicates a low probability for the high-rank solutions and thus essentially dual ambiguity. This paper investigates the characteristics of ASCAT high-rank wind solutions under different conditions with the objective of developing a method for rejecting the spurious high-rank solutions. The implementation of this rejection procedure improves the effectiveness of the ASCAT wind quality control (QC) and ambiguity removal procedures This work was supported in part by the European Organisation for the Exploitation of Meteorological Satellites Ocean and Sea Ice Satellite Application Facility Associated Scientist project under Reference CDOP-SG06-VS03 and in part by the Spanish Ministry of Science and Innovation (MICINN) National R&D project under Reference AYA2010-22062-C05. The authors would like to thank J.-R. Bidlot and ECMWF for providing the GTS buoy wind data set (already quality controlled). The ASCAT level 1b data are provided by EUMETSAT. The software used in this paper was developed through the EUMETSAT NWP SAF. The ECMWF data were retrieved from the ECMWF MARS archive. The TMI data are available from the Web site of Remote Sensing Systems (http://www.ssmi.com/). The authors greatly appreciate the three reviewers who helped to improve the paper Peer reviewed |
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