Data from the Advanced Synthetic Aperture Radar (ASAR) on-board ENVISAT is available for the UK from 2002-2009. The raw data for alternating polarisation, wide swath and image modes were acquired by the Landmap project from ESA and processed to produce 8 and 32-bit greyscale and multi-difference colour composite geotiff images.

• Image mode: Provides high resolution (30m) for HH and VV polarisation products
• Alternating Polarisation (AP): 30m resolution data in the following polarisations (each AP mode has 2 polarisations) – HH/VV, HH/HV, VV/VH
• Wide swath: 150m resolution data in VV or HH polarisations over a wider sampling area.

• HH - Horizontal polarisation transmitted, horizontal received
• VV - Vertical transmitted, vertical received
• HV - Horizontal transmitted, vertical received
• VH - Vertical transmitted, horizontal received

The Joint Information Systems Committee (JISC) funded Landmap service which ran from 2001 to July 2014 collected and hosted a large amount of earth observation data for the majority of the UK. After removal of JISC funding in 2013, the Landmap service is no longer operational, with the data now held at the NEODC.

The ASAR data are available to UK academics and students. To apply for access, please

1. Register as a NEODC user. If you already are a NEODC registered user, skip this step. If you have forgotten your NEODC user ID and/or password, please contact the NEODC helpdesk at neodc@rl.ac.uk.
2. Apply for access to the Landmap data. Application involves the agreement with the Landmap terms of use.

The data are available in geotiff format which can be opened in many earth observation image processing software including open/free software such as Erdas ER viewer and the freely available Basic ERS & Envisat (A)ATSR and Meris Toolbox (BEAM) or NEST (Next ESA SAR Toolbox). Geotiff files are TIFF files which have geographic metadata embedded as tags within the TIFF file. The geographic metadata can then be used to position the image in the correct location and geometry on the screen of a geographic information display. The data are split into the three modes acquired by Landmap (alternating polarisation, wide swath and image modes). The various polarisations can be determined from the filename:

• hh - Horizontal polarisation transmitted, horizontal received.
• vv - Vertical transmitted, vertical received
• hv - Horizontal transmitted, vertical received
• vh - Vertical transmitted, horizontal received

Software

Erdas ER viewer, available free of charge, can be used to open raster image formats such as TIFF, GeoTiff, IMG, ECW, ERS, ALG, DAT and many more, and is capable of handling large file sizes.

Basic ERS & Envisat (A) ATSR and Meris Toolbox (BEAM): BEAM is an open-source toolbox and development platform for viewing, analysing and processing of remote sensing raster data. Originally developed to facilitate the utilisation of image data from Envisat's optical instruments, BEAM now supports a growing number of other raster data formats such as GeoTIFF and NetCDF as well as data formats of other Earth Observation (EO) sensors such as Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Very High Resolution Radiometer (AVHRR), AVNIR, Polarised Radiation Imaging and Spectroscopy Mission (PRISM) and Compact High Resolution Imaging Spectrometer (CHRIS). Various data and algorithms are supported by dedicated extension plug-ins.

NEST (Next ESA SAR Toolbox) is an ESA open source toolbox under the GNU GPL license for reading, processing, analysing and visualising ESA (ERS-1/2, ENVISAT, SENTINEL-1) and other spaceborne SAR data (TerraSAR-X, RADARSAT 1-2, COSMO-SkyMed, JERS-1, ALOS PALSAR) processed to Level-1 or higher.

Documentation

• ASAR specifications and details
• ASAR product handbook

Links to further information

• The Landmap project ASAR website, this site may be offline soon after 1st August 2014 due to removal of JISC (Joint Information Systems Committee) funding, see below for an archived version of ths site
• An archived version of the Landmap project ASAR site, hosted by the Internet Archive project
• The ESA ASAR website

If you have queries about these pages or about obtaining the ASAR data from the NEODC then you should contact the NEODC Support team. Your query should be answered within one working day. When follow-up work is required, the NEODC support team will carry out the work as quickly and efficiently as possible.