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OCRA radiometric cloud fractions for GOME-2 on MetOp-A/B

Lutz, Ronny and Loyola, Diego and Gimeno Garcia, Sebastian and Romahn, Fabian (2016) OCRA radiometric cloud fractions for GOME-2 on MetOp-A/B. Atmospheric Measurement Techniques (AMT), 9, pp. 2357-2379. Copernicus Publications. doi: 10.5194/amt-9-2357-2016. ISSN 1867-1381.

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Official URL: http://www.atmos-meas-tech.net/9/2357/2016/amt-9-2357-2016.html


This paper describes an approach for cloud parameter retrieval (radiometric cloud-fraction estimation) using the polarization measurements of the Global Ozone Monitoring Experiment-2 (GOME-2) onboard the MetOp-A/B satellites. The core component of the Optical Cloud Recognition Algorithm (OCRA) is the calculation of monthly cloud-free reflectances for a global grid (resolution of 0.2° in longitude and 0.2° in latitude) to derive radiometric cloud fractions. These cloud fractions will serve as a priori information for the retrieval of cloud-top height (CTH), cloud-top pressure (CTP), cloud-top albedo (CTA) and cloud optical thickness (COT) with the Retrieval Of Cloud Information using Neural Networks (ROCINN) algorithm. This approach is already being implemented operationally for the GOME/ERS-2 and SCIAMACHY/ENVISAT sensors and here we present version 3.0 of the OCRA algorithm applied to the GOME-2 sensors. Based on more than five years of GOME-2A data (April 2008 to June 2013), reflectances are calculated for  ≈ 35 000 orbits. For each measurement a degradation correction as well as a viewing-angle-dependent and latitude-dependent correction is applied. In addition, an empirical correction scheme is introduced in order to remove the effect of oceanic sun glint. A comparison of the GOME-2A/B OCRA cloud fractions with colocated AVHRR (Advanced Very High Resolution Radiometer) geometrical cloud fractions shows a general good agreement with a mean difference of −0.15 ± 0.20. From an operational point of view, an advantage of the OCRA algorithm is its very fast computational time and its straightforward transferability to similar sensors like OMI (Ozone Monitoring Instrument), TROPOMI (TROPOspheric Monitoring Instrument) on Sentinel 5 Precursor, as well as Sentinel 4 and Sentinel 5. In conclusion, it is shown that a robust, accurate and fast radiometric cloud-fraction estimation for GOME-2 can be achieved with OCRA using polarization measurement devices (PMDs).

Item URL in elib:https://elib.dlr.de/105561/
Document Type:Article
Title:OCRA radiometric cloud fractions for GOME-2 on MetOp-A/B
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Lutz, RonnyUNSPECIFIEDhttps://orcid.org/0000-0002-7215-3642
Loyola, DiegoUNSPECIFIEDhttps://orcid.org/0000-0002-8547-9350
Date:30 May 2016
Journal or Publication Title:Atmospheric Measurement Techniques (AMT)
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
Page Range:pp. 2357-2379
Publisher:Copernicus Publications
Keywords:Remote Sensing, Clouds
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Atmospheric and climate research
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Atmospheric Processors
Deposited By: Lutz, Dr. Ronny
Deposited On:03 Aug 2016 14:41
Last Modified:28 Mar 2023 23:46

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