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Verlagsausgabe
DOI: 10.5445/IR/1000038943
Veröffentlicht am 24.05.2018
Originalveröffentlichung
DOI: 10.5194/amt-5-831-2012
Scopus
Zitationen: 7
Web of Science
Zitationen: 7

How to average logarithmic retrievals?

Funke, B.; Clarmann, T. von

Abstract:
Calculation of mean trace gas contributions from profiles obtained by retrievals of the logarithm of the abundance rather than retrievals of the abundance itself are prone to biases. By means of a system simulator, biases of linear versus logarithmic averaging were evaluated for both maximum likelihood and maximum a priori retrievals, for various signal to noise ratios and atmospheric variabilities. These biases can easily reach ten percent or more. As a rule of thumb we found for maximum likelihood retrievals that linear averaging better represents the true mean value in cases of large local natural variability and high signal to noise ratios, while for small local natural variability logarithmic averaging often is superior. In the case of maximum a posteriori retrievals, the mean is dominated by the a priori information used in the retrievals and the method of averaging is of minor concern. For larger natural variabilities, the appropriateness of the one or the other method of averaging depends on the particular case because the various biasing mechanisms partly compensate in an unpredictable manner. This complication arises mainl ... mehr


Zugehörige Institution(en) am KIT Fakultät für Physik (PHYSIK)
Institut für Meteorologie und Klimaforschung - Atmosphärische Spurenstoffe und Fernerkundung (IMK-ASF)
Publikationstyp Zeitschriftenaufsatz
Jahr 2012
Sprache Englisch
Identifikator ISSN: 1867-1381, 1867-8548
URN: urn:nbn:de:swb:90-389434
KITopen ID: 1000038943
HGF-Programm 12.04.03; LK 01
Erschienen in Atmospheric measurement techniques
Band 5
Heft 4
Seiten 831-841
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