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Validation of GOME-2/MetOp-A total water vapour column using reference radiosonde data from the GRUAN network

Antón, M. and Loyola, Diego and Roman, R. and Vömel, H. (2015) Validation of GOME-2/MetOp-A total water vapour column using reference radiosonde data from the GRUAN network. Atmospheric Measurement Techniques, 8 (3), pp. 1135-1145. Copernicus Publications. DOI: 10.5194/amt-8-1135-2015 ISSN 1867-1381

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Official URL: http://www.atmos-meas-tech.net/8/1135/2015/amt-8-1135-2015.html

Abstract

The main goal of this paper is to validate the total water vapour column (TWVC) measured by the Global Ozone Monitoring Experiment-2 (GOME-2) satellite sensor and generated using the GOME Data Processor (GDP) retrieval algorithm developed by the German Aerospace Centre (DLR). For this purpose, spatially and temporally collocated TWVC data from highly accurate sounding measurements for the period January 2009–May 2014 at six sites are used. These balloon-borne data are provided by the GCOS Reference Upper-Air Network (GRUAN). The correlation between GOME-2 and sounding TWVC data is reasonably good (determination coefficient, R2, of 0.89) when all available radiosondes (1400) are employed in the inter-comparison. When cloud-free cases (544) are selected by means of the satellite cloud fraction (CF < 5%), the correlation exhibits a remarkable improvement (R2 ~ 0.95). Nevertheless, the analysis of the relative differences between GOME-2 and GRUAN data shows a mean absolute bias error (weighted with the combined uncertainty derived from the estimated errors of both data sets) of 15% for all-sky conditions (9% for cloud-free cases). These results evidence a notable bias in the satellite TWVC data against the reference balloon-borne measurements, partially related to the cloudy conditions during the satellite overpass. The detailed analysis of the influence of cloud properties – CF, cloud top albedo (CTA) and cloud top pressure (CTP) – on the satellite-sounding differences reveals, as expected, a large effect of clouds in the GOME-2 TWVC data. For instance, the relative differences exhibit a large negative dependence on CTA, varying from −6 to −23% when CTA rises from 0.3 to 0.8. Furthermore, the satellite-sounding TWVC differences show a strong dependence on the satellite solar zenith angle (SZA) for values above 50°. Hence the smallest relative differences found in this satellite-sounding comparison are achieved for those cloud-free cases with satellite SZA below 50°. Finally, the relative differences also show a negative dependence on the reference TWVC values, e.g. changing from +10% (TWVC below 10 mm) to −10% (TWVC above 40 mm) when cloud-free conditions with SZA below 50° are selected. Overall, relative differences within ±10% with respect to reference sounding data for a large range of TWVC values can be considered as a good result for satellite retrievals.

Item URL in elib:https://elib.dlr.de/100688/
Document Type:Article
Title:Validation of GOME-2/MetOp-A total water vapour column using reference radiosonde data from the GRUAN network
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Antón, M.Extremadura, SpainUNSPECIFIED
Loyola, DiegoDLR-IMFUNSPECIFIED
Roman, R.Universidad de Valladolid, SpainUNSPECIFIED
Vömel, H.Deutscher Wetterdienst, GermanyUNSPECIFIED
Date:6 March 2015
Journal or Publication Title:Atmospheric Measurement Techniques
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:8
DOI :10.5194/amt-8-1135-2015
Page Range:pp. 1135-1145
Editors:
EditorsEmail
Munro, R.EUMETSAT, Darmstadt, Germany
Tamminen, J.1Earth Observation Unit, Finnish Meteorological Institute, Helsinki, Finland
Stammes, P.Royal Netherlands Meteorological Institute (KNMI), De Bilt, the Netherlands
Publisher:Copernicus Publications
ISSN:1867-1381
Status:Published
Keywords:GOME-2 Water vapour
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):R - Vorhaben Ozon-SAF (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Atmospheric Processors
Deposited By: Loyola, Dr.-Ing. Diego
Deposited On:09 Dec 2015 09:20
Last Modified:02 May 2019 14:13

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