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Envisat MERIS Reduced Resolution - Level 2 [MER_RR__2P/ME_2_RRG]
MERIS RR Level 2 is a Reduced Resolution (RR) Geophysical product for Ocean, Land and Atmosphere. Each MERIS Level 2 geophysical product is derived from a MERIS Level 1 product and auxiliary parameter files specific to the MERIS Level 2 processing. The MERIS RR Level 2 product has a Sentinel 3-like format starting from the 4th reprocessing data released to users in July 2020. The data package is composed of NetCDF 4 files containing instrumental and scientific measurements, and a Manifest file, which contains metadata information related to the description of the product. A Level 2 product is composed of 64 measurement files containing mainly: 13 files containing Water-leaving reflectance, 13 files containing Land surface reflectance and 13 files containing the TOA reflectance (for all bands except those dedicated to measurement of atmospheric gas - M11 and M15), and several files containing additional measurement on Ocean, Land and Atmospheric parameters. The Auxiliary data used are listed in the Manifest file associated to each product. MERIS was operating continuously on the day side of the Envisat orbit (descending track). RR data was acquired over 43.5 minutes in each orbit, i.e. 80% of the descending track.
Envisat MERIS Reduced Resolution - Level 1 [MER_RR__1P/ME_1_RRG]
The MERIS Level 1 Reduced Resolution (RR) product contains the Top of Atmosphere (TOA) upwelling spectral radiance measurements at reduced resolution. 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 RR 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 measurements 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 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 1 products are the averaged band-pass of each pixel over the instrument field of view. The Auxiliary data used are listed in the Manifest file associated to each product. MERIS was operating continuously on the day side of the Envisat orbit (descending track). RR data was acquired over 43.5 minutes in each orbit, i.e. 80% of the descending track.
Envisat MERIS Full Resolution - Level 2 [MER_FRS_2P/ME_2_FRG]
MERIS FR Level 2 is a Full-Resolution Geophysical product for Ocean, Land and Atmosphere. Each MERIS Level 2 geophysical product is derived from a MERIS Level 1 product and auxiliary parameter files specific to the MERIS Level 2 processing. The MERIS FR Level 2 product has Sentinel 3-like format starting from the 4th reprocessing data released to users in July 2020. The data package is composed of NetCDF 4 files containing instrumental and scientific measurements, and a Manifest file which contains metadata information related to the description of the product. A Level 2 product is composed of 64 measurement files containing: 13 files containing Water-leaving reflectance, 13 files containing Land surface reflectance and 13 files containing the TOA reflectance (for all bands except those dedicated to measurement of atmospheric gas - M11 and M15), and several files containing additional measurements on Ocean, Land and Atmospheric parameters and annotation. The Auxiliary data used are listed in the Manifest file associated to each product. The Level 2 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/Level 1. Thus the estimated size of the Level 2 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.
Aura OMI complete NASA dataset
The OMI observations provide the following capabilities and features: A mapping of ozone columns at 13 km x 24 km and profiles at 13 km x 48 km A measurement of key air quality components: NO2, SO2, BrO, HCHO, and aerosol The ability to distinguish between aerosol types, such as smoke, dust and sulfates The ability to measure aerosol absorption capacity in terms of aerosol absorption optical depth or single scattering albedo A measurement of cloud pressure and coverage A mapping of the global distribution and trends in UV-B radiation. The OMI data are available in the following four levels: Level 0, Level 1B, Level 2, and Level 3. Level 0 products are raw sensor counts. Level 0 data are packaged into two-hour "chunks" of observations in the life of the spacecraft (and the OMI aboard it) irrespective of orbital boundaries. They contain orbital swath data. Level 1B processing takes Level 0 data and calibrates, geo-locates and packages the data into orbits. They contain orbital swath data. Level 2 products contain orbital swath data. Level 3 products contain global data that are composited over time (daily or monthly) or over space for small equal angle (latitude longitude) grids covering the whole globe.
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.
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.
Pléiades full archive and tasking
The Pléiades twins (1A and 1B) deliver very high-resolution optical data (up to 0.5 m resolution Panchromatic and Colour and 2 m Multispectral) and offer a daily revisit capability to any point on the globe. The swath width is approximately 20 km (with a nadir footprint). The ortho-products are automatically generated by the Pléiades ground segment, based on SRTM or Reference3D database. The projection available for Pléiades ortho-products is UTM, datum WGS84. Bands combinations:: Pansharpened: colour image at 0.5 m resolution Bundle: (0.5 m panchromatic image + 2 m multispectral image) Processing levels: Primary: The Primary product is the processing level closest to the natural image acquired by the sensor. This product restores perfect collection conditions: the sensor is placed in rectilinear geometry, and the image is clear of all radiometric distortion. Standard Ortho: The Ortho product is a georeferenced image in Earth geometry, corrected from acquisition and terrain off-nadir effects. Tailored Ortho: Aside from the Standard Ortho product, when different specifications are needed, a custom orthorectification, with a more precise 3D model provided by the client or acquired for the purpose, can be provided on demand. As per ESA policy, very high-resolution imagery of conflict areas cannot be provided.
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.
SPOT 1-5 ESA archive
The ESA SPOT 1-5 collection is a dataset of SPOT 1 to 5 Panchromatic and Multispectral products that ESA collected over the years. The HRV(IR) sensor onboard SPOT 1-4 provides data at 10 m spatial resolution Panchromatic mode (-1 band) and 20 m (Multispectral mode -3 or 4 bands). The HRG sensor on board of SPOT-5 provides spatial resolution of the imagery to < 3 m in the panchromatic band and to 10 m in the multispectral mode (3 bands). The SWIR band imagery remains at 20 m. The dataset mainly focuses on European and African sites but some American, Asian and Greenland areas are also covered. Spatial coverage: Check the spatial coverage of the collection on a map available on the Third Party Missions Dissemination Service. The SPOT Collection
CLOSED - Announcement of Opportunity for S5PVT (Sentinel-5 Precursor Calibration and Validation Team)
In the framework of the Copernicus programme, ESA offered an announcement of opportunity to support the Sentinel-5 Precursor Calibration and Validation Team Call.
AVHRR Level-1B Local Area Coverage Imagery
This collection is composed of AVHRR L1B products (1.1 km) reprocessed from the NOAA POES and Metop AVHRR sensors data acquired at the University of Dundee and University of Bern ground stations and from the ESA and University of Bern data historical archive. The product format is the NOAA AVHRR Level 1B that combines the AVHRR data from the HRPT stream with ancillary information like Earth location and calibration data which can be applied by the user. Other appended parameters are time codes, quality indicators, solar and satellite angles and telemetry. Two data collections cover Europe and the neighbouring regions in the period of 1 January 1981 to 31 December 2020 and the acquired data in the context of the 1-KM project in the ‘90s. During the early 1990’s various groups, including the International Geosphere-Biosphere Programme (IGBP), the Commission of the European Communities (CEC), the Moderate Resolution Imaging Spectrometer (MODIS) Science Team and ESA concluded that a global land 1 KM AVHRR data set would have been crucial to study and develop algorithms for several land products for the Earth Observing System. USGS, NOAA, ESA and other non-U.S. AVHRR receiving stations endorsed the initiative to collect a global land 1-km multi-temporal AVHRR data set over all land surfaces using NOAA's TIROS "afternoon" polar-orbiting satellite. On 1 April 1992, the project officially began up to the end of 1999 with the utilisation of 23 stations worldwide plus the NOAA local area coverage (LAC) on-board recorders. The global land 1-km AVHRR dataset is composed of 5 channels, raw AVHRR dataset at 1.1 km resolution from the NOAA-11 and NOAA-14 satellites covering land surfaces, inland water and coastal areas. Global Land 1 km AVHRR Data Set Project HRPT Ground Station Network (as of 1 April 1992) and Acquisition Areas for LAC Recorded Data Spatial coverage: Check the spatial coverage of the collection on a map available on the Third Party Missions Dissemination Service: AVHRR L1B 1.1 KM AVHRR L1B LAC Out-of-Europe.
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.
Spire live and historical data
The data collected by Spire from its 100 satellites launched into Low Earth Orbit (LEO) has a diverse range of applications, from analysis of global trade patterns and commodity flows to aircraft routing to weather forecasting. The data also provides interesting research opportunities on topics as varied as ocean currents and GNSS-based planetary boundary layer height. The following products can be requested: GNSS Polarimetric Radio Occultation (STRATOS) Novel Polarimetric Radio Occultation (PRO) measurements collected by three Spire satellites are available over 15 May 2023 to 30 November 2023. PRO differ from regular RO (described below) in that the H and V polarizations of the signal are available, as opposed to only Right-Handed Circularly Polarized (RHCP) signals in regular RO. The differential phase shift between H and V correlates with the presence of hydrometeors (ice crystals, rain, snow, etc.). When combined, the H and V information provides the same information on atmospheric thermodynamic properties as RO: temperature, humidity, and pressure, based on the signal’s bending angle. Various levels of the products are provided. GNSS Reflectometry (STRATOS) GNSS Reflectometry (GNSS-R) is a technique to measure Earth’s surface properties using reflections of GNSS signals in the form of a bistatic radar. Spire collects two types of GNSS-R data: Near-Nadir incidence LHCP reflections collected by the Spire GNSS-R satellites, and Grazing-Angle GNSS-R (i.e., low elevation angle) RHCP reflections collected by the Spire GNSS-RO satellites. The Near-Nadir GNSS-R collects DDM (Delay Doppler Map) reflectivity measurements. These are used to compute ocean wind / wave conditions and soil moisture over land. The Grazing-Angle GNSS-R collects 50 Hz reflectivity and additionally carrier phase observations. These are used for altimetry and characterization of smooth surfaces (such as ice and inland water). Derived Level 1 and Level 2 products are available, as well as some special Level 0 raw intermediate frequency (IF) data. Historical grazing angle GNSS-R data are available from May 2019 to the present, while near-nadir GNSS-R data are available from December 2020 to the present. Name Temporal coverage Spatial coverage Description Data format and content Application Polarimetric Radio Occultation (PRO) measurements 15 May 2023 to 30 November 2023 Global PRO measurements observe the properties of GNSS signals as they pass through by Earth's atmosphere, similar to regular RO measurements. The polarization state of the signals is recorded separately for H and V polarizations to provide information on the anisotropy of hydrometeors along the propagation path leoOrb.sp3. This file contains the estimated position, velocity and receiver clock error of a given Spire satellite after processing of the POD observation file proObs. Level 0 - Raw open loop carrier phase measurements at 50 Hz sampling for both linear polarization components (horizontal and vertical) of the occulted GNSS signal. h(v)(c)atmPhs. Level 1B - Atmospheric excess phase delay computed for each individual linear polarization component (hatmPhs, vatmPhs) and for the combined (“H” + “V”) signal (catmPhs). Also contains values for signal-to-noise ratio, transmitter and receiver positions and open loop model information. polPhs. Level 1C - Combines the information from the hatmPhs and vatmPhs files while removing phase continuities due to phase wrapping and navigation bit modulation. patmPrf. Level 2 - Bending angle, dry refractivity, and dry temperature as a function of mean sea level altitude and impact parameter derived from the “combined” excess phase delay (catmPhs) PRO measurements add a sensitivity to ice and precipitation content alongside the traditional RO measurements of the atmospheric temperature, pressure, and water vapor. Near-Nadir GNSS Reflectometry (NN GNSS-R) measurements 25 January-2024 to 24 July 2024 Global Tracks of surface reflections as observed by the near-nadir pointing GNSS-R antennas, based on Delay Doppler Maps (DDMs). gbrRCS.nc. Level 1B - Along-track calibrated bistatic radar cross-sections measured by Spire conventional GNSS-R satellites. gbrNRCS.nc. Level 1B - Along-track calibrated bistatic and normalized radar cross-sections measured by Spire conventional GNSS-R satellites. gbrSSM.nc. Level 2 - Along-track SNR, reflectivity, and retrievals of soil moisture (and associated uncertainties) and probability of frozen ground. gbrOcn.nc. Level 2 - Along-track retrievals of mean square slope (MSS) of the sea surface, wind speed, sigma0, and associated uncertainties. NN GNSS-R measurements are used to measure ocean surface winds and characterize land surfaces for applications such as soil moisture, freeze/thaw monitoring, flooding detection, inland water body delineation, sea ice classification, etc. Grazing angle GNSS Reflectometry (GA GNSS-R) measurements 25 January 2024 to 24 July 2024 Global Tracks of surface reflections as observed by the limb-facing RO antennas, based on open-loop tracking outputs: 50 Hz collections of accumulated I/Q observations grzRfl.nc. Level 1B - Along-track SNR, reflectivity, phase delay (with respect to an open loop model) and low-level observables and bistatic radar geometries such as receiver, specular reflection, and the transmitter locations. grzIce.nc. Level 2 - Along-track water vs sea ice classification, along with sea ice type classification. grzAlt.nc. Level 2 - Along-track phase-delay, ionosphere-corrected altimetry, tropospheric delay, and ancillary models (mean sea surface, tides). GA GNSS-R measurements are used to 1) characterize land surfaces for applications such as sea ice classification, freeze/thaw monitoring, inland water body detection and delineation, etc., and 2) measure relative altimetry with dm-level precision for inland water bodies, river slopes, sea ice freeboard, etc., but also water vapor characterization from delay based on tropospheric delays. Additionally, the following products (better detailed in the ToA) can be requested but the acceptance is not guaranteed and shall be evaluated on a case-by-case basis: Other STRATOS measurements: profiles of the Earth’s atmosphere and ionosphere, from December 2018 ADS-B Data Stream: monthly subscription to global ADS-B satellite data, available from December 2018 AIS messages: AIS messages observed from Spire satellites (S-AIS) and terrestrial from partner sensor stations (T-AIS), monthly subscription available from June 2016 The products are available as part of the Spire provision with worldwide coverage. All details about the data provision, data access conditions and quota assignment procedure are described in the Terms of Applicability.
TanSat AGCS and CAPI products
The Atmospheric Carbon-dioxide Grating Spectrometer (ACGS) instrument is pushbroom spectrometer operating in NIR and SWIR bands which allows the measuring of CO2 mole fraction. The available ACGS products have a temporal coverage between March 2017 and January 2020 (not all days included in the time frame): L1A DS: Sample Dark Calibration sample product L1A GL: Sample Glint Sample products L1A LS: Sample Lamp Calibration sample product L1A ND: Principal-Plane Nadir Sample product L1A ZS: Sample Z-Axis Solar Calibration Sample L1B CAL DS: Sample Dark Calibration product L1B CAL LS: Sample Lamp Calibration product L1B CAL ZS: Sample Z-Axis Solar Calibration product L1B SCI GL: Sample Glint Science product L1B SCI ND: Principal-Plane Nadir Science product. The Cloud Aerosol Polarization Imager (CAPI) is a pushbroom radiometer in VIS, NIR and SWIR bands for the observation of aerosols and clouds optical properties. The CAPI products are available in a time range from July 2019 and January 2020 (not all days included in the time frame): L1A ND: Principal-Plane Nadir product L1B ND 1000M: Principal-Plane Nadir products at 1000 m resolution (1375 nm, 1640 nm) L1B ND 250M: Principal-Plane Nadir products at 250 m resolution (380 nm, 670 nm, 870 nm) L1B ND GEOQK: Principal-Plane Nadir georeferenced at 250 m resolution L1B ND GEO1K: Principal-Plane Nadir georeferenced at 1000 m resolution L1B ND OBC: Principal-Plane Nadir on-board calibrator product L2 ND CLM: Principal-Plane Nadir cloud flag product.
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).
Atmospheric Thematic Data Product [MWR_TDPATM]
This is the Atmospheric Thematic Data Product (TDP) V1 resulting from the ESA FDR4ALT project and containing Total Column Water Vapour (TCWV), Cloud Liquid Water Path (LWP), Atmospheric Attenuation of the altimeter backscattering coefficient at Ku-band (AttKu), and Wet Tropospheric Correction (WTC), retrieved from observations of the Microwave Radiometer (MWR) instruments flown on-board the ERS-1, and ERS-2, and Envisat satellites. Compared to existing datasets, the Atmospheric TDP demonstrates notable improvements in several aspects: Improved temporal coverage, especially for ERS-2 Improved L0 -> 1 processing Two different corrections are provided based on a neural network retrieval or on a 1D-VAR approach 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.