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DATA
Fundamental Data Record for Atmospheric Composition [ATMOS__L1B]
The Fundamental Data Record (FDR) for Atmospheric Composition UVN v.1.0 dataset is a cross-instrument Level-1 product [ATMOS__L1B] generated in 2023 and resulting from the ESA FDR4ATMOS project. The FDR contains selected Earth Observation Level 1b parameters (irradiance/reflectance) from the nadir-looking measurements of the ERS-2 GOME and Envisat SCIAMACHY missions for the period ranging from 1995 to 2012. The data record offers harmonised cross-calibrated spectra with focus on spectral windows in the Ultraviolet-Visible-Near Infrared regions for the retrieval of critical atmospheric constituents like ozone (O3), sulphur dioxide (SO2), nitrogen dioxide (NO2) column densities, alongside cloud parameters. The FDR4ATMOS products should be regarded as experimental due to the innovative approach and the current use of a limited-sized test dataset to investigate the impact of harmonization on the Level 2 target species, specifically SO2, O3 and NO2. Presently, this analysis is being carried out within follow-on activities. The FDR4ATMOS V1 is currently being extended to include the MetOp GOME-2 series. Product format For many aspects, the FDR product has improved compared to the existing individual mission datasets: GOME solar irradiances are harmonised using a validated SCIAMACHY solar reference spectrum, solving the problem of the fast-changing etalon present in the original GOME Level 1b data; Reflectances for both GOME and SCIAMACHY are provided in the FDR product. GOME reflectances are harmonised to degradation-corrected SCIAMACHY values, using collocated data from the CEOS PIC sites; SCIAMACHY data are scaled to the lowest integration time within the spectral band using high-frequency PMD measurements from the same wavelength range. This simplifies the use of the SCIAMACHY spectra which were split in a complex cluster structure (with own integration time) in the original Level 1b data; The harmonization process applied mitigates the viewing angle dependency observed in the UV spectral region for GOME data; Uncertainties are provided. Each FDR product provides, within the same file, irradiance/reflectance data for UV-VIS-NIR special regions across all orbits on a single day, including therein information from the individual ERS-2 GOME and Envisat SCIAMACHY measurements. FDR has been generated in two formats: Level 1A and Level 1B targeting expert users and nominal applications respectively. The Level 1A [ATMOS__L1A] data include additional parameters such as harmonisation factors, PMD, and polarisation data extracted from the original mission Level 1 products. The ATMOS__L1A dataset is not part of the nominal dissemination to users. In case of specific requirements, please contact EOHelp. Please refer to the README file for essential guidance before using the data. All the new products are conveniently formatted in NetCDF. Free standard tools, such as Panoply, can be used to read NetCDF data. Panoply is sourced and updated by external entities. For further details, please consult our Terms and Conditions page. Uncertainty characterisation One of the main aspects of the project was the characterization of Level 1 uncertainties for both instruments, based on metrological best practices. The following documents are provided: General guidance on a metrological approach to Fundamental Data Records (FDR) Uncertainty Characterisation document Effect tables NetCDF files containing example uncertainty propagation analysis and spectral error correlation matrices for SCIAMACHY (Atlantic and Mauretania scene for 2003 and 2010) and GOME (Atlantic scene for 2003) reflectance_uncertainty_example_FDR4ATMOS_GOME.nc reflectance_uncertainty_example_FDR4ATMOS_SCIA.nc
ERS ATSR L1B Brightness Temperature/Radiance [ER1_AT_1_RBT / ER2_AT_1_RBT]
Band measurements with associated uncertainty estimates. The ERS-1/2 ATSR Level 1B Brightness Temperature/Radiance products (RBT) contain top of atmosphere (TOA) brightness temperature (BT) values for the infra-red channels and radiance values for the visible channels, when available, on a 1-km pixel grid. The visible channels are only available for the ATSR-2 instrument. Values for each channel and for the nadir and oblique views occupy separate NetCDF files within the Sentinel-SAFE format, along with associated uncertainty estimates. Additional files contain cloud flags, land and water masks, and confidence flags for each image pixel, as well as instrument and ancillary meteorological information. The ATSR-1 and ATSR-2 products [ER1_AT_1_RBT and ER2_AT_1_RBT], in NetCDF format stemming from the 4th ATSR reprocessing, are precursors of Envisat AATSR and Sentinel-3 SLSTR data. They have replaced the former L1B products [AT1_TOA_1P and AT2_TOA_1P] in Envisat format from the 3rd reprocessing. Users with Envisat-format products are recommended to move to the new Sentinel-SAFE like/NetCDF format products, and consult the ERS ATSR Product Notice Readme document. The processing updates that have been put in place and the expected scientific improvements for the ERS ATSR 4th reprocessing data have been outlined in full in the User Documentation for (A)ATSR 4th Reprocessing Products
Announcement of Opportunity for S3VT (Sentinel-3 Validation Team)
In the framework of a Copernicus collaborative agreement ESA and EUMETSAT invite interested groups and individuals to support the Sentinel-3 Validation Team (S3VT).
Announcement of Opportunity for G-POD
ESA is offering all scientists the possibility to perform bulk processing and/or validation of their own algorithms exploiting the large ESA Earth-observation archive.
ERS PRARE Precise Orbit Product (ERS.ORB.POD/ERS.ORB/PRC)
The precise orbit results from a data reduction process in which all available tracking data (Single-Lens Reflex, radar altimeter crossovers, PRARE range and Doppler data) and most accurate correction, transformation and dynamical models are taken into account and in which high level numerical procedures are applied. These orbits are "optimal" achievable representations of the real orbital motion under the circumstances of tracking situation and the "state of the art" model situation. The precise orbit product for the ERS satellites are the satellite ephemeris (position and velocity vector) including time tag, given in a well-defined reference frame, together with the nominal satellite attitude information and a radial orbit correction. Several orbit solutions are currently distributed: A new set of ORB POD (Precise Orbit Determination - REAPER v2) computed with the most updated model standards for the complete ERS-1 and ERS-2 mission. A previous set of ORB POD (REAPER v1) data already available on the ESA dissemination site since 2014, covering the ERS-1 full mission and the ERS-2 mission up to July 2003. ORB PRC which is the original Precise Orbit dataset computed during the ERS mission operations for ERS-1 and ERS-2. In the new POD dataset (REAPER v2) for the ERS-1 and ERS-2 missions, two different orbit solutions are provided together with the combined solution to be used for processing of the radar altimeter measurements and the determination of geodetic/geophysical products: those computed by DEOS (Delft Institute of Earth Observation and Space Systems), and those generated by ESOC (European Space Operations Centre) using different software (GEODYN and NAPEOS respectively). Careful evaluation of the various solutions of REAPER v2 has shown that the DEOS solution for both ERS-1 and ERS-2 has the best performance and is recommended to be used as reference. See the ERS Orbit Validation Report. For the previous version of the POD data set (REAPER v1), with ERS-2 mission data only up to 2003, three different orbit solutions together with the combined solution are available. These precise orbits for ERS-1 and ERS-2 have been computed at DEOS, ESOC, and GFZ (Deutschen GeoForschungsZentrums) using different software and different altimeter databases. Combined solutions have been created using three individual solutions for each satellite. All orbits were derived using consistent models in the same LPOD2005 terrestrial reference frame. These new orbit solutions show notable improvement with respect to DGME04 orbits (Scharroo and Visser, 1998). Thus, RMS crossover differences of new orbits improved by 4-9 mm. Careful evaluation of the various solutions has shown that the combined solution for both ERS-1 and ERS-2 has the best performance. All POD orbit files (REAPER v1/v2) are available in SP3c format.
GOME Total Column Water Vapour Climate product
The GOME Total Column Water Vapour (TCWV) Climate product was generated by the Max Planck Institute for Chemistry (MPIC), and the German Aerospace Center (DLR) within the ESA GOME-Evolution project. It is a Level 3 type product containing homogenized time-series of the global distribution of TCWV spanning over more than two decades (1995-2015). The data is provided as single netCDF file, containing monthly mean TCWV (units kg/m2) with 1-degree resolution, and is based on measurements from the satellite instruments ERS-2 GOME, Envisat SCIAMACHY, and MetOp-A GOME-2. Details are available in the paper by Beirle et al, 2018. Please also consult the GOME TCWV Product Quality Readme file before using the data.
ERS-2 GOME Spectral Product L1
GOME Level 1 products contain Earthshine radiance at the Top of the Atmosphere and solar irradiance spectra. They were generated by DLR on behalf of the European Space Agency with Level 1 GOME Data Processor (GDP-L1) starting from the Extracted GOME Calibration (EGOC) Level 0 data files. Originally raw detector signals (binary Analog to Digital Converted units) of the science measurements plus calibration constants were provided (dataset version 4 and lower), but following the end of the operational phase of the ERS-2 mission (2 July 2011), as part of ESA's post-operational algorithm improvement activities (Coldewey-Egbers et al., 2018), the GOME Level 1 data type was entirely revised and a dataset of fully calibrated and ready to use data was generated with GOME processor version 5.1. The version 5.1 data bring relevant quality improvements for the revised calibration approach, compensating aging and instrument degradation, and provide enhanced accessibility. The version 5.1 data are in NetCDF format and differ fundamentally from the previous GOME Level 1 data, having the Envisat proprietary format and basically containing Level 1a data where a dedicated extraction software tool had to be applied by end user to obtain spectrally and radiometrically calibrated radiances (including the correction for polarisation, leakage current and stray light). Such calibrations are now applied to the version 5.1 L1b data product in the standard processing. Users of GOME Level 1 products are strongly recommended to migrate to the latest reprocessed dataset. Please consult the GOME Product Quality Readme file before using the data.
ERS-2 GOME Total Column Amount of Trace Gases Product
GOME Level 2 products were generated by DLR on behalf of the European Space Agency, and are the end result of the Level 1 to 2 reprocessing campaign of GOME Level 1 version 4 data with Level 2 GOME Data Processor (GDP) version 5.0 (HDF-5 format). The GOME Level 2 data product comprises the product header, total column densities of ozone and nitrogen dioxide and their associated errors, cloud properties and selected geo-location information, diagnostics from the Level 1 to 2 algorithms and a small amount of statistical information.