GOME-2 Cloud top height and optical depth retrieval using ROCINN V3.0 Gimeno García 1 , Sebastián 1 ; Lutz, Ronny 1 ; Romahn, Fabian 1 ; Loyola, Diego 1 ; Spurr, Robert 2 1 German Aerospace Center (DLR) Remote Sensing Technology Institute Oberpfaffenhofen, GERMANY 2 RT SOLUTIONS Inc. Cambridge, MA, USA June 10, 2015 ESA ATMOS 2015, Heraklion, 08-12 June 2015 1
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GOME-2 Cloud top height and optical depth retrieval using ...seom.esa.int/atmos2015/files/presentation123.pdf · ROCINN_CAL: UPAS GDP 4.8 – 01 Jul 2009 Cloud Optical Thickness MODIS
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GOME-2 Cloud top height and opticaldepth retrieval using ROCINN V3.0
OCRA: Optical Cloud Recognition Algorithm ROCINN: Retrieval Of Cloud Information through Neural Networks
OCRA/ROCINN schematic
ESA ATMOS 2015, Heraklion, 08-12 June 2015 6
Outline
1 Motivation
2 Retrieval strategy
3 OCRA
4 ROCINN – CAL & CRB
5 Results: GOME2-A cloud products
6 Conclusions
7 Outlook
ESA ATMOS 2015, Heraklion, 08-12 June 2015 7
OCRA – in short
OCRA is a RGB color space approach
determine monthly cloud free reflectance maps
map actual reflectance measurements to cloud (radiometric) fraction
radiometric cloud fraction:GOME2-A and GOME2-B merged together
⇒ See poster #47, Lutz et al.:Cloud Fraction Determination for GOME-2 A/B with OCRA V3.0 (!)
ESA ATMOS 2015, Heraklion, 08-12 June 2015 8
Outline
1 Motivation
2 Retrieval strategy
3 OCRA
4 ROCINN – CAL & CRB
5 Results: GOME2-A cloud products
6 Conclusions
7 Outlook
ESA ATMOS 2015, Heraklion, 08-12 June 2015 9
ROCINN – CAL & CRB
Cloud fraction (CF) is retrieved using a RGB color space approach→ OCRA
Cloud Top Height and Albedo (CTH, CTA) and Cloud OpticalThickness (COT) are retrieved in the Oxygen A-band usingregularization theory→ ROCINN
CRB: Clouds are treated as Reflecting BoundariesI Lambertian Equivalent Reflectors (LER)I simple and (numerically) robustI popular in the atmospheric gas retrieval communityI retrieved cloud parameters can greatly deviate from reality
CAL: Clouds are treated As horizontal homogeneous LayersI photon cloud penetration is allowedI multiple scattering is accounted forI modeled radiance contains information below the cloud layerI retrieved CTH is closer to the actual CTH
ESA ATMOS 2015, Heraklion, 08-12 June 2015 10
ROCINN – CAL cloud model
KISS – Keep It Simple Strategy (G. Marsaglia – RNG)
One cloud layer
Liquid water droplets
Spherical particles – Mie scattering theory
Modified gamma particle size distribution (α=6, β=0.11)
⇒ cloud optical propertiesI Single scattering albedoI Scattering phase functionI Optical thickness (not important: to be fit)