Name: Envisat DORIS Precise Orbit [DOR_VOR_AX]
Creator: European Space Agency
License: https://earth.esa.int/eogateway/documents/20142/1564626/Terms-and-Conditions-for-the-use-of-ESA-Data.pdf

DORIS

Passive Remote Sensing

Positioning/Navigation

Radio

Envisat

Earthquakes

Environmental Impacts

Human Dimensions

Natural Hazards and Disaster Risk

Solid Earth

Tectonics

The latest version of the Envisat DORIS Precise Orbit product, DOR_VOR_AX, was generated by the Centre de Traitement Doris Poseidon (CTDP) using the Geophysical Data Records F standards (GDR-F). The product is used to obtain the satellite orbital parameters (latitude, longitude, height and height rate) by using orbit computation routines.

The most significant changes related to the GDR-F standards concern the new ocean tide model (FES2014) and the updated Terrestrial Reference Frame (ITRF2014). The new standards significantly improve all Precise Orbit Determination (POD) metrics with respect to GDR-E. The mean difference and variance of Sea Surface Height (SSH) at crossovers is slightly reduced.

The DOR_VOR_AX product adopts the Envisat format, and the size is 0.2 Mbytes per orbit.

Users are recommended to apply the GDR-F version, but the previous datasets are still available (i.e. GDR-D and GDR-E versions).

See further details in the <a href="/eogateway/documents/20142/37627/Readme-file-for-Envisat-DORIS-POD.pdf" target="_blank">readme file</a>&nbsp;for Envisat DORIS Precise Orbit Determination files.

<figure class="centered-mobile-centered"><a data-lightbox="DOR-VOR-AX-Description" data-title="Caption of image" href="/eogateway/documents/20142/1565579/DOR-VOR-AX-Description.png"><img alt="DOR-VOR-AX-Description" class="centered-mobile-centered" src="/eogateway/documents/20142/1565579/DOR-VOR-AX-Description-tm.png" /> </a>

<figcaption>Comparison of Envisat Sea Level Anomaly trends obtained using DORIS Precise Orbit GDR-E and F standards. North/South patterns are evident. Credits: CNES/CLS.</figcaption>
</figure>

European Space Agency, 2021, Envisat Precise Orbit product - GDR Version F.

European Space Agency, 2019, Envisat Precise Orbit product - GDR Version E.

DORIS Products Specifications

DOR_VOR_AX GDR-F Reprocessing – Technical Documentation

DOR_VOR_AX File Structure

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Utilisation of this data is subject to ESA's Earth Observation Terms and Conditions.

This collection is composed of a subset of ALOS-1 PRISM (Panchromatic Remote-sensing Instrument for Stereo Mapping) OB1 L1C products from the <a href="https://earth.esa.int/eogateway/catalog/alos-prism-l1c">ALOS PRISM L1C collection</a> (DOI: 10.57780/AL1-ff3877f) which have been chosen so as to provide a cloud-free coverage over Europe. 70% of the scenes contained within the collection have a cloud cover percentage of 0%, while the remaining 30% of the scenes have a cloud cover percentage of no more than 20%.

The collection is composed of PSM_OB1_1C EO-SIP products, with the PRISM sensor operating in OB1 mode with three views (Nadir, Forward and Backward) at 35 km width.

ALOS PRISM L1C European Coverage Cloud Free

The FSSCat collection provides hyperspectral data coverage over a number of locations around the world, as measured by the HyperScout 2 sensor.

The FSSCat hyperspectral data products are comprised of 50 spectral bands, covering a spectral range of 450 – 950 nm with a spectral resolution of 18 nm (at FWHM). Imagery is available with an along-track ground sampling distance (GSD) of 75 m. To ensure a high degree of radiometric accuracy, HyperScout 2 data are validated through comparison with Sentinel-2 data products.

The processing level of the data is L1C – calibrated top-of-atmosphere radiance, reflectance or brightness temperature. The raster type of the L1C data product is a GRID – a 2D or 3D raster where the (geo)location of the data is uniquely defined by the upper left pixel location of the raster and the pixel size of the raster, and the projection parameters of the raster (if georeferenced). The third dimension can e.g. be a spectral or third spatial dimension.

The L-1C VNIR data product includes a hyperspectral cube of TOA reflectance in the VNIR range, as well as relevant meta-data that adheres to EDAP's best practice guidelines. This product consists of georeferenced and ortho-rectified image tiles that contain spectral reflectance data at the top-of-the-atmosphere. Each image tile contains radiometrically corrected and ortho-rectified band images that are projected onto a map, as well as geolocation information and the coordinate system used. Additionally, each image pixel provides TOA spectral reflectance data in scaled integers, conversion coefficients for spectral radiance units, viewing and solar zenith and azimuth angles, and quality flags.

FSSCat products

In cooperation with CONAE (Comisión Nacional de Actividades Espaciales), ESA is launching an Announcement of Opportunity for the international scientific community to access data from the SAOCOM mission for science and EO-based applications development.

Announcement of Opportunity for SAOCOM

GEOSAT-2 Portugal coverage is a collection of 2021 data over the Portugal area, including islands. The available dataset has a cloud cover less than 10%, and is acquired up to 1m resolution with Geometric accuracy &lt;6m CE90 based on Copernicus DEM @10m.

<figure class="centered-mobile-centered"><a data-lightbox="GEOSAT-2-Portugal" data-title="GEOSAT-2 Portugal 2021 - Spatial Coverage of the Dataset" href="/documents/20142/4279060/GEOSAT2_Portugal_Coverage.png"><img alt="GEOSAT-2 Portugal 2021 - Spatial Coverage of the Dataset" src="/documents/20142/4279060/GEOSAT2_Portugal_Coverage_Smaller.jpg/3e2c84ea-17e7-c8b6-ed57-b079e1851142?t=1677155961453&amp;download=true" style="margin: 10px;" /></a>

<figcaption style="text-align: center;">GEOSAT-2 Portugal 2021 - Spatial Coverage of the Dataset</figcaption>
</figure>

The following product types are available:

<ul>
	<li>Pan-sharpened (4 bands, 321 Natural Colours or 432 False Colours): A four-band image, resulting from adding the information of each multispectral band to the panchromatic band. The fusion does not preserves all spectral features of the multispectral bands, so it should not be used for radiometric purposes. Resolution 1m; Bands: All, R-G-B or Ni-R-G</li>
	<li>Bundle: Panchromatic (1m resolution) + Multispectral bands (4m resolution): five-band image containing the panchromatic and multispectral products packaged together, with band co-registration.</li>
</ul>

The available processing level is L1C orthorectified: a calibrated and radiometrically corrected product, manually orthorectified and resampled to a map grid.

<table class="eogtable">
	<tbody>
		<tr class="eogtable-heading">
			<td rowspan="2">Product Type</td>
			<td colspan="2">Processing Level and Spatial Resolution</td>
		</tr>
		<tr class="eogtable-heading">
			<td>L1B (native)</td>
			<td>L1C (ortho)</td>
		</tr>
		<tr>
			<td>Pan-sharpened</td>
			<td>1.0m</td>
			<td>1.0m</td>
		</tr>
		<tr>
			<td>Bundle (PAN+MS)</td>
			<td>1.0m (P), 4.0m (MS)</td>
			<td>1.0m (P), 4.0m(MS)</td>
		</tr>
	</tbody>
</table>

GEOSAT-2 Portugal Coverage 2021

A large number of European cities are covered by this dataset; for each city you can find one or more Cartosat-1 ortho image products and one or more Euro-Maps 3D DSM tiles clipped to the extent of the ortho coverage.

The Euro-Maps 3D DSM is a homogeneous, 5 m spaced Digital Surface Model semi-automatically derived from 2.5 m Cartosat-1 in-flight stereo data with a vertical accuracy of 10 m. The very detailed and accurate representation of the surface is achieved by using a sophisticated and well adapted algorithm implemented on the basis of the Semi-Global Matching approach. The final product includes several pixel-based quality and traceability layers:

<ul>
	<li>The dsm layer (*_dsm.tif) contains the elevation heights as a geocoded raster file</li>
	<li>The source layer (*_src.tif) contains information about the data source for each height value/pixel</li>
	<li>The number layer (*_num.tif) contains for each height value/pixel the number of IRS-P5 Cartosat-1 stereo pairs used for the generation of the DEM</li>
	<li>The quality layer (*_qc.tif) is set to 1 for each height/pixel value derived from IRS-P5 Cartosat-1 data and which meets or exceeds the product specifications</li>
	<li>The accuracy vertical layer (*_acv.tif) contains the absolute vertical accuracy for each quality controlled height value/pixel.</li>
</ul>

The ortho image is a Panchromatic image at 2.5 m resolution. The following table defines the offered product types.

<table class="eogtable">
	<tbody>
		<tr class="eogtable-heading">
			<td>EO-SIP product type</td>
			<td>Description</td>
		</tr>
		<tr>
			<td>PAN_PAM_3O</td>
			<td>IRS-P5 Cartosat-1 ortho image</td>
		</tr>
		<tr>
			<td>DSM_DEM_3D</td>
			<td>IRS-P5 Cartosat-1 DSM</td>
		</tr>
	</tbody>
</table>

Envisat DORIS Precise Orbit [DOR_VOR_AX]

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