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APOLLO_NG – a probabilistic interpretation of the APOLLO legacy for AVHRR heritage channels

Klüser, Lars and Killius, Niels and Gesell, Gerhard (2015) APOLLO_NG – a probabilistic interpretation of the APOLLO legacy for AVHRR heritage channels. Atmospheric Measurement Techniques, 8, pp. 4155-4170. Copernicus Publications. DOI: 10.5194/amt-8-4155-2015 ISSN 1867-1381

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Official URL: http://www.atmos-meas-tech.net/8/4155/2015/


The cloud processing scheme APOLLO (AVHRR Processing scheme Over cLouds, Land and Ocean) has been in use for cloud detection and cloud property retrieval since the late 1980s. The physics of the APOLLO scheme still build the backbone of a range of cloud detection algorithms for AVHRR (Advanced Very High Resolution Radiometer) heritage instruments. The APOLLO_NG (APOLLO_NextGeneration) cloud processing scheme is a probabilistic interpretation of the original APOLLO method. It builds upon the physical principles that have served well in the original APOLLO scheme. Nevertheless, a couple of additional variables have been introduced in APOLLO_NG. Cloud detection is no longer performed as a binary yes/no decision based on these physical principles. It is rather expressed as cloud probability for each satellite pixel. Consequently, the outcome of the algorithm can be tuned from being sure to reliably identify clear pixels to conditions of reliably identifying definitely cloudy pixels, depending on the purpose. The probabilistic approach allows retrieving not only the cloud properties (optical depth, effective radius, cloud top temperature and cloud water path) but also their uncertainties. APOLLO_NG is designed as a standalone cloud retrieval method robust enough for operational near-realtime use and for application to large amounts of historical satellite data. The radiative transfer solution is approximated by the same two-stream approach which also had been used for the original APOLLO. This allows the algorithm to be applied to a wide range of sensors without the necessity of sensorspecific tuning. Moreover it allows for online calculation of the radiative transfer (i.e., within the retrieval algorithm) giving rise to a detailed probabilistic treatment of cloud variables. This study presents the algorithm for cloud detection and cloud property retrieval together with the physical principles from the APOLLO legacy it is based on. Furthermore a couple of example results from NOAA-18 are presented.

Item URL in elib:https://elib.dlr.de/99263/
Document Type:Article
Title:APOLLO_NG – a probabilistic interpretation of the APOLLO legacy for AVHRR heritage channels
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Date:12 October 2015
Journal or Publication Title:Atmospheric Measurement Techniques
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
DOI :10.5194/amt-8-4155-2015
Page Range:pp. 4155-4170
Publisher:Copernicus Publications
Keywords:AVHRR Clouds Remote Sensing Cloud detection APOLLO
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 Atmosphären- und Klimaforschung
Location: Oberpfaffenhofen
Institutes and Institutions:German Remote Sensing Data Center > Atmosphere
Deposited By: Klüser, Dr. Lars
Deposited On:10 Nov 2015 11:27
Last Modified:02 May 2019 14:13

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