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DATA
Fundamental Data Records for Radiometry [MWR_FDR___]
This dataset is a Fundamental Data Record (FDR) resulting from the ESA FDR4ALT project. The Fundamental Data Record for Radiometry V1 products contain intercalibrated Top of the Atmosphere brightness temperatures at 23.8 and 36.5 GHz. The collection covers data for the ERS-1, ERS-2 and Envisat missions, and is built upon a new processing of Level 0 data, incorporating numerous improvements in terms of algorithms, flagging procedures, and corrections. Compared to existing datasets, the Radiometry FDR demonstrates notable improvements in several aspects: New solutions for instrumental effects (ERS Reflector loss, Skyhorn, and Sidelobe corrections) Native sampling rate of 7Hz with enhanced coverage The FDR4ALT products are available in NetCDF format. Free standard tools for reading NetCDF data can be used. Information for expert altimetry users is also available in a dedicated NetCDF group within the products. Please consult the FDR4ALT Product User Guide before using the data. The FDR4ALT datasets represent the new reference data for the ERS/Envisat altimetry missions, superseding any previous mission data. Users are strongly encouraged to make use of these datasets for optimal results.
Fundamental Data Records for Altimetry [ALT_FDR___]
This dataset is a Fundamental Data Record (FDR) resulting from the ESA FDR4ALT project. The Fundamental Data Record for Altimetry V1 products contain Level 0 and Level 1 altimeter-related parameters including calibrated radar waveforms and supplementary instrumental parameters describing the altimeter operating status and configuration through the satellite lifetime. The data record consists of data for the ERS-1, ERS-2 and Envisat missions for the period ranging from 1991 to 2012, and bases on the Level 1 data obtained from previous ERS REAPER and ENVISAT V3.0 reprocessing efforts incorporating new algorithms, flags, and corrections to enhance the accuracy and reliability of the data. For many aspects, the Altimetry FDR product has improved compared to the existing individual mission datasets: New neural-network waveform classification, surface type classification, distance to shoreline and surface flag based on GSHHG Instrumental calibration information directly available in the product Improved Orbit solutions Correction of REAPER drawbacks (i.e., time jumps and negative waveforms) The FDR4ALT products are available in NetCDF format. Free standard tools for reading NetCDF data can be used. Information for expert altimetry users is also available in a dedicated NetCDF group within the products. Please consult the FDR4ALT Product User Guide before using the data. The FDR4ALT datasets represent the new reference data for the ERS/Envisat altimetry missions, superseding any previous mission data. Users are strongly encouraged to make use of these datasets for optimal results.
Sea Ice Thematic Data Product [ALT_TDP_SI]
This is the Sea Ice Thematic Data Product (TDP) V1 resulting from the ESA FDR4ALT project and containing the sea ice related geophysical parameters, along with associated uncertainties: snow depth, radar and sea-ice freeboard, sea ice thickness and concentration. The collection covers data for the ERS-1, ERS-2 and Envisat missions, and bases on Level 1 data coming from previous reprocessing (ERS REAPER and the Envisat V3.0) but taking into account the improvements made at Level 0/Level 1 in the frame of FDR4ALT (ALT FDR). The Sea Ice TDP provides data from the northern or southern hemisphere in two files corresponding to the Arctic and Antarctic regions respectively for the winter periods only, i.e., October to June for the Arctic, and May to November for the Antarctic. For many aspects, the Sea Ice TDP is very innovative: First time series of sea-ice thickness estimates for ERS Homogeneous calibration, allowing the first Arctic radar freeboard time series from ERS-1 (1991) to CryoSat-2 (2021) Uncertainties estimated along-track with a bottom-up approach based on dominant sources ERS pulse blurring error corrected using literature procedure [Peacock, 2004] The FDR4ALT products are available in NetCDF format. Free standard tools for reading NetCDF data can be used. Information for expert altimetry users is also available in a dedicated NetCDF group within the products. Please consult the FDR4ALT Product User Guide before using the data. The FDR4ALT datasets represent the new reference data for the ERS/Envisat altimetry missions, superseding any previous mission data. Users are strongly encouraged to make use of these datasets for optimal results.
Land Ice Thematic Data Product [ALT_TDP_LI]
This is the Land Ice Thematic Data Product (TDP) V1 resulting from the ESA FDR4ALT project and containing estimates of ice sheet surface elevation and associated uncertainties. The collection covers data for three different missions: ERS-1, ERS-2 and Envisat, and based on Level 1 data coming from previous reprocessing (ERS REAPER and the Envisat V3.0) but taking into account the improvements made at Level 0/Level 1 in the frame of FDR4ALT (ALT FDR). The Land Ice TDP focuses specifically on the ice sheets of Greenland and Antarctica, providing these data in different files. For many aspects, the Land Ice Level 2 and Level 2+ processing is very innovative: Improved relocation approach correcting for topographic effects within the beam footprint to identify the Point of Closest Approach Homogeneous timeseries of surface elevation measurements at regular along-track reference nodes. The FDR4ALT products are available in NetCDF format. Free standard tools for reading NetCDF data can be used. Information for expert altimetry users is also available in a dedicated NetCDF group within the products. Please consult the FDR4ALT Product User Guide before using the data. The FDR4ALT datasets represent the new reference data for the ERS/Envisat altimetry missions, superseding any previous mission data. Users are strongly encouraged to make use of these datasets for optimal results.
Envisat ASAR AP Co- and Cross-polar L0 [ASA_APC/APH/APV_0P]
The ASAR Alternating Polarization Mode Level 0 (Co-polar and Cross-polar H and V) products contain time-ordered Annotated Instrument Source Packets (AISPs) corresponding to one of the three possible polarisation combinations: HH & HV, VV & VH and HH & VV, respectively. The echo samples in the AISPs have been compressed to 4 bits/sample using FBAQ. This is a high-rate, narrow swath mode, so data is only acquired for partial orbit segments. There are two co-registered images per acquisition and may be from one of seven different image swaths. The Level 0 product was produced systematically for all data acquired within this mode. Data Size: 56-100 km across track x 100 km along track. There are three AP Mode Level 0 products: ASA_APH_0P: The Cross-polar H Level 0 product corresponds to the polarisation combination HH/HV. ASA_APV_0P: The Cross-polar V Level 0 product corresponds to the polarisation combination VV/VH. ASA_APC_0P: The Co-polar Level 0 product corresponds to the polarisation combination HH/VV= H and H received/V transmit and V received.
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.
Envisat RA-2 Geophysical Data Record - GDR [RA2_GDR__2P]
This is a RA-2 Geophysical Data Record (GDR) Full Mission Reprocessing (FMR) V3 product containing radar range and orbital altitude, wind speed, wave height, water vapour from the MWR and geophysical corrections. This FMR follows the first Envisat Altimetry reprocessing Version (V2.1) completed in 2012. The GDR and S-GDR data products were reprocessed for all cycles from 6 to 113 (May 2002 to April 2012) into a homogeneous standard in NetCDF format (close to Sentinel-3). For many aspects, the V3.0 reprocessed data are better than the previous dataset: In terms of available and valid data, the coverage is better, notably thanks to a better availability of MWR data at the beginning of the mission In terms of performance at cross-overs, the quality is improved: the annual signal and average of Mean SSH is decreased, as well as the standard deviation The new MWR characteristics were shown to improve largely the global quality of data. As well as the new tide model, the new MSS and the new orbit standard The Global and regional Mean Sea Level trend is very weakly impacted though the effort was put, this time, on the mesoscale restitution, rather than long term drift, as during V2.1 reprocessing. Please consult the Envisat RA-2/MWR Product Quality Readme file PDF before using the data.
Envisat RA-2 Sensor and Geophysical Data Record - SGDR [RA2_MWS__2P]
This is a RA-2 Sensor and Geophysical Data Record (SGDR) Full Mission Reprocessing (FMR) V3 product. This FMR follows the first Envisat Altimetry reprocessing Version (V2.1) completed in 2012. The GDR and S-GDR data products were reprocessed for all cycles from 6 to 113 (May 2002 to April 2012) into a homogeneous standard in NetCDF format (close to Sentinel-3). The Sensor Data Record (SGDR) Product from RA-2/MWR includes the data in the GDR product (RA-2 geophysical data, MWR data) and also RA-2 averaged waveforms (18Hz) and RA-2 individual waveforms (1800Hz). This product is a continuation of ERS RA data. This data product has a coverage of 1 pass and pole to pole, a spatial sampling of about 390 m along track and a size of 31 to 40 MB, depending on presence of individual waveforms. The radiometric accuracy is 0.2 dB and auxiliary data include: Orbit state vectors (DORIS, FOS), RA2 and MWR characterisation data, Platform attitude, Gain calibration, USO frequency, ECMWF data, time relation, leap second, Ionospheric corrections, geoid, mean sea surface, slope data, and tide model (ocean, earth, loading, pole). Please consult the Envisat RA-2/MWR Product Quality Readme file before using the data.
ERS-1/2 Radar Altimeter REAPER Geophysical Data Record - GDR [ERS_ALT_2]
This is a RA Geophysical Data Record (GDR) product containing radar range, orbital altitude, wind speed, wave height and water vapour from the ATSR/MWR as well as geophysical corrections. The REAPER (REprocessing of Altimeter Products for ERS) product is generated by applying a similar processing as for Envisat RA-2 on the Level 1b consolidated waveforms using 4 different re-trackers, RA calibration improvement, new precise orbit solution (POD), new ionospheric corrections (NICO09 until 1998 and GIM up to 2003), ECMWF ERA-interim model and updated SSB tables. This product contains two data rates: a low rate of 1 Hz and a high rate of 20 Hz. Most 1 Hz data is also represented at 20 Hz, while microwave radiometer (ATSR/MWR) data and the atmospheric and geophysical corrections are only given at 1 Hz. The REAPER GDR (ERS_ALT_2_) is a global product including data over ocean, ice and land. It should be noted that this product differs from the Envisat RA2 in the following ways: The product format; which is NetCDF (more details can be found in the Product Handbook, and not PDS The product is delivered based on orbit acquisition and not per pass (pole-to-pole). This product is extended through Envisat RA-2 data.
ERS-1/2 Radar Altimeter REAPER Sensor Geophysical Data Record - SGDR [ERS_ALT_2S]
This is a RA Geophysical Data Record (GDR) product containing radar range, orbital altitude, wind speed, wave height and water vapour from the ATSR/MWR as well as geophysical corrections. The REAPER (REprocessing of Altimeter Products for ERS) product is generated by applying a similar processing as for Envisat RA-2 on the Level 1b consolidated waveforms using 4 different re-trackers, RA calibration improvement, new precise orbit solution (POD), new ionospheric corrections (NICO09 until 1998 and GIM up to 2003), ECMWF ERA-interim model and updated SSB tables. This product contains two data rates: a low rate of 1 Hz and a high rate of 20 Hz. Most 1 Hz data is also represented at 20 Hz, while microwave radiometer (ATSR/MWR) data and the atmospheric and geophysical corrections are only given at 1 Hz. The REAPER GDR (ERS_ALT_2_) is a global product including data over ocean, ice and land. It should be noted that this product differs from the Envisat RA2 in the following ways: The product format; which is NetCDF (more details can be found in the Product Handbook, and not PDS The product is delivered based on orbit acquisition and not per pass (pole-to-pole). This product is extended through Envisat RA-2 data.
ERS-1/2 Radar Altimeter REAPER METEO Product - [ERS_ALT_2M]
This is a RA Meteo product containing only the 1 Hz parameters for altimeter (surface range, satellite altitude, wind speed and significant wave height at nadir) and ATSR/MWR data (brightness temperature at 23.8 GHz and 36.5 GHz, water vapour content, liquid water content) used to correct altimeter measurements. It also contains the full geophysical corrections. This product corresponds to a subset of the REAPER GDR product (ERS_ALT_2_). The REAPER (REprocessing of Altimeter Products for ERS) product is generated by applying a similar processing as for Envisat RA-2 on the Level 1b consolidated waveforms using 4 different re-trackers, RA calibration improvement, new precise orbit solution (POD), new ionospheric corrections (NICO09 until 1998 and GIM up to 2003), ECMWF ERA-interim model and updated SSB tables. This product contains only the low rate of 1 Hz data. The REAPER Meteo (ERS_ALT_2M) is a global product including data over ocean, ice and land. It should be noted that this product differs from the Envisat RA2 in the following ways: The product format; which is NetCDF (more details can be found in the Product Handbook), and not PDS The product is delivered based on orbit acquisition and not per pass (pole-to-pole). This product is extended through Envisat RA-2 data.
ERS-1/2 SAR IM Medium Resolution L1 [SAR_IMM_1P]
This ERS Medium Resolution stripline product is generated from the Image Mode Level 0 Product. Stripline image products contain image data for an entire segment, up to a maximum size of 10 minutes per product for IM mode. The processor concatenates together several sub-images called "slices" that were processed separately on a dataset-by-dataset basis in order to form the entire stripline image. The product is processed to an approximately 150 m x 150 m resolution and has a radiometric resolution that is good enough for ice applications. This product has a lower spatial resolution than the SAR_IMP_1P and SAR_IMS_1P products. Product Characteristics: Pixel size: 5 m (ground range – across track) x 75 m (azimuth – along track) Scene area: 100 km (range) x at least 102.5 km Scene Size: 1300 pixels (range) x at least 1350 lines (azimuth) Pixel depth: 16 bits unsigned integer- Total product volume: at least 3.5 MB Projection: Ground-range Number of looks: 8 (azimuth) x 7 (range).
ERS-1/2 SAR IM Precision L1 [SAR_IMP_1P]
The SAR Precision product is a multi-look (speckle-reduced), ground range image acquired in Image Mode. This product type is most applicable to users interested in remote sensing applications, but is also suitable for calibration purposes. The products are calibrated and corrected for the SAR antenna pattern and range-spreading loss. Radar backscatter can be derived from the products for geophysical modelling, but no correction is applied for terrain-induced radiometric effects. The images are not geocoded, and terrain distortion (foreshortening and layover) has not been removed. The numbering sequence relates to the satellite position and therefore differs between Ascending and Descending scenes. Product characteristics: Pixel size: 12.5 m (range - across track) x 12.5 m (azimuth - along track) Scene area: 100 km (range) x at least 102.5 km (azimuth) Scene size: 8000 pixels range x at least 8200 lines (azimuth) Pixel depth: 16 bits unsigned integer Total product volume: 125 MB Projection: Ground-range Number of looks: 3.
ERS-1/2 SAR IM Single Look Complex L1 [SAR_IMS_1P]
The SAR SLC product is a single look complex acquired in Image Mode. It is a digital image, with slant range and phase preserved, generated from raw SAR data using up-to-date auxiliary parameters. The products are intended for use in SAR quality assessment, calibration and interferometric applications. A minimum number of corrections and interpolations are performed on the data. Absolute calibration parameters (when available) are provided in the product annotation. Product characteristics: Pixel size: 8 m (range - across track) x 4 m (azimuth - along track – varying slightly depending on acquisition Pulse Repetition Frequency) Scene area: 100 km (range) x at least 102.5 km (azimuth) Scene size: 5000 samples (range) x at least 30000 lines (azimuth) Pixel depth: 32 bits signed integer (16 bits I, 16 bits Q) Total product volume: 575 MB Projection: Slant range- Number of looks: 1.
ERS-1/2 SAR IM L0 [SAR_IM__0P]
This SAR Level 0 product is acquired in Image Mode. The products consist of the SAR telemetry data and are supplied as standard scenes. It also contains all the required auxiliary data necessary for data processing. The product serves two main purposes: For testing ERS SAR processors independently from the HDDR system For users interested in full SAR data processing. Product characteristics: Scene area: 100 km (range - across track) x full segment length (azimuth - along track) Scene size: 5616 samples (range) x full segment length (azimuth) Pixel depth: 10 bits signed integer (5 bits I, 5 bits Q) Projection: Slant range.
ERS-1/2 SCATTEROMETER Ocean Wind field and Sea Ice probability [ASPS20.H/ASPS20.N]
The ASPS Level 2 products contain, for each node: the radar backscattering sigma nought for the three beams of the instrument, the four aliased wind solutions (Rank 1-4 wind vector) and the de-aliased wind vector flag, the sea-ice probability and sea-ice flag, the YAW quality flag. The wind retrieval is performed with the CMOD5N geophysical model function derived by ECMWF to compute the neutral winds rather than 10 m winds. ASPS L2.0 High resolution products are provided with a spatial resolution of 25x25 km and a grid spacing of 12.5 km. ASPS L2.0 Nominal resolution products are provided with a spatial resolution of 50x50 km and a grid spacing of 25 km. One product covers one orbit from ascending node crossing. Please consult the Product Quality Readme file before using the ERS ASPS data.
Envisat ASAR AP Medium Resolution L1 [ASA_APM_1P]
This ASAR Alternating Polarization Medium Resolution Image product has been generated from Level 0 data collected when the instrument was in Alternating Polarisation Mode. The product has lower geometric resolution but higher radiometric resolution than ASA_APP and contains one or two co-registered images corresponding to one of the three polarisation combination sub modes (HH and VV, HH and HV, VV and VH). This product has been processed using the SPECAN algorithm and contains radiometric resolution good enough for ice applications and covers a continuous area along the imaging swath. The ASAR AP L0 full mission data archive has been bulk processed to Level 1 (ASA_APM_1P) in Envisat format with the IPF-ASAR processor Version 6.03. Spatial Resolution: 150 m ground range x 150 m azimuth.
Envisat MERIS Full Resolution - Level 1 [MER_FRS_1P/ME_1_FRG]
The MERIS Level 1 Full Resolution (FR) product contains the Top of Atmosphere (TOA) upwelling spectral radiance measurements. The in-band reference irradiances for the 15 MERIS bands are computed by averaging the in-band solar irradiance of each pixel. The in-band solar irradiance of each pixel is computed by integrating the reference solar spectrum with the band-pass of each pixel. The MERIS FR Level 1 product has Sentinel 3-like format starting from the 4th reprocessing data released to users in July 2020. Each measurement and annotation data file is in NetCDF 4. The Level 1 product is composed of 22 data files: 15 files containing radiances at each band (one band per file), accompanied by the associated error estimates, and 7 annotation data files. The 15 sun spectral flux values provided in the instrument data file of the Level 1 products are the in-band reference irradiances adjusted for the Earth-sun distance at the time of measurement. The band-pass of each pixel is derived from on-ground and in-flight characterisation via an instrument model. The values "Band wavelength" and "Bandwidth" provided in the Manifest file of the Level 1b products are the averaged band-pass of each pixel over the instrument field of view. Auxiliary data are also listed in the Manifest file associated to each product. The Level 1 FR product covers the complete instrument swath. The product duration is not fixed and it can span up to the time interval of the input Level 0 (for a maximum of 20 minutes). Thus the estimated size of the Level 1 FR is dependent on the start/stop time of the acquired segment. During the Envisat mission, acquisition of MERIS Full Resolution data was subject to dedicated planning based on on-demand ordering and coverage of specific areas according to operational recommendations and considerations. See yearly and global density maps to get a better overview of the MERIS FR coverage.
Envisat ASAR Global Monitoring L1 [ASA_GM1_1P]
This product has been generated from Level 0 data collected when the instrument was in Global Monitoring Mode. One product covers a full orbit. The product includes slant range to ground range corrections. This strip-line product is the standard for ASAR Global Monitoring Mode. It is processed to approximately 1 km resolution using the SPECAN algorithm. The swath width is approximately 400 km. The ASAR GM L0 full mission data archive has been bulk processed to Level 1 (ASA_GM1_1P) in Envisat format with the IPF-ASAR processor Version 6.03. Spatial Resolution: 1 km ground range x 1 km azimuth.
Envisat ASAR IM Single Look Complex L1 [ASA_IMS_1P]
This data product represents a single-look, complex, slant-range, digital image generated from Level 0 ASAR data collected when the instrument is in Image Mode. Seven possible swaths in HH or VV polarisation are available. The product is primarily intended for use in SAR quality assessment and calibration or applications requiring complex SAR images such as interferometry, and can be used to derive higher level products. The spatial coverage is about 100 km along track per 56 - 100 km across track, and the radiometric resolution is 1 look in azimuth, 1 look in range. The file size is 741 Mbytes. It is worth highlighting that Azimuth pixel spacing depends on Earth-Satellite relative velocity and actual PRF and slant range pixel spacing is given by ASAR sampling frequency (19.208 Mhz). Auxiliary data include: Orbit state vector, Time correlation parameters, Main Processing parameters ADS, Doppler Centroid ADS, Chirp ADS, Antenna Elevation Pattern ADS, Geolocation Grid ADS, SQ ADS. Spatial Resolution: Approximately 8m slant range x approximately 4m azimuth.