ODESA is the answer to the requirements expressed by the MERIS Quality Working Group (QWG) and by the MERIS Validation Team (MVT), and more widely by the international user community of MERIS.
|ODESA provides the users with a complete level 2 processing environment for the MERIS instrument
as well as for the future
ESA optical sensors on board Sentinel 3.
ODESA supplies the user community with the MERIS Ground Segment development platform MEGS®, including source code, embedded in an efficient framework for testing and for validation activities. These validation facilities include match-up processing & analysis, data set selection & analysis, level 3 products generation & analysis and the possibility to perform remote processing, e.g. for testing purpose and for validation activities requiring large amounts of data.ODESA is structured around five modules described below.
“Access MERIS data from remote processing facility available to qualified processors”
The ODESA on-line processing is the web-oriented facility allowing registered users to run the level 2 processor on dedicated remote servers: selecting the processor version, getting intermediate output data, using uploaded LUTs, selecting specified locations and time ranges. This facility gives access to intermediate data of the processing, like intermediate atmospheric correction quantities. Several qualified processing versions are proposed to the user (i.e. nominal MERIS level 2 processing, qualified algorithm updates) as well as the possibility of modifying Auxiliary Data Files (ADF) and limiting the computation on the branch of interest (Ocean, Land, Cloud).
Note: registration is very easy; it simply consists in providing an e-mail address. The access is immediately granted with a password supplied by e-mail.
“Download the MERIS level 2 processor (MEGS®) and its operation environment”
The ODESA source code distribution allows external users to implement their own version of any sub-module of the ODESA L2 processor. The distribution package contains the source code, required libraries, GUI, tools and associated documentation, providing any user an extraordinary opportunity to customise the MERIS level 2 processor using its own algorithms and auxiliary data. A test data set is delivered within the package, allowing testing the local installation. This package allows to run the nominal MERIS level 2 software (identified as the reference configuration in the delivery package) and run user-modified MERIS level 2 software (modified source code including possible LUT overwriting).
“Analyze ODESA outputs with standard tools”
The ODESA processor generates output files in classical ENVISAT format but also in netCDF (breakpoints and new level 2 output parameters). This module provides various links to compatible tools allowing the visualization and possible post-processing of the ODESA files.
“Validate your algorithm and get it qualified to access the MERIS on-line processing”
A protocol, approved by the MERIS QWG, allows users to validate their MERIS level 2 processing update(s). The basis of this protocol will be the comparison of their results with the nominal MERIS level 2 results and/or in-situ data through the MERMAID matchups database. Once a user has its own customised level 2 processor ready, he may have access to a database of matchups (a MERMAID data set, selected by user request and under configuration control, will be made available), allowing him to compare its results with those obtained with the current official MERIS level 2 processor. The next version of ODESA will allow the processing of direct MERMAID extractions that contains all information to produce the level 2 data, instead of processing MERIS level 1b products. When the comparison is completed, the user may ask for a "Qualification". The "qualified" status is required for an implementation request of the customised processor in a dedicated processing cluster (e.g. ESA Grid Processing on Demand or ACRI-ST cluster) for a mass processing task (e.g. several months of processed data). At the end of this process, the new products may also be stamped as ESA supported products and made available to the whole Ocean Colour community. The updated part of the MERIS processor may also be implemented as a new option in a next release of the on-line and source code distributed processor.