Instrument - Imaging Radars
Products Information The information provided in this page is applicable to the latest ASAR products. Level 0 products are derived from the raw satellite data and are the lowest level product available. Level 1 products are then processed from L0 products. Higher level products (Level 2) can then be derived from L1 products; however, this is currently only done with Wave mode. The general layout for all products includes the following records: Main Product Header (MPH) - The MPH has a fixed length and the format is identical across all Envisat products. Specific Product Header (SPH) - The SPH is defined for each product and provides additional information related to the processing, which is applicable to the whole product. Data Set (DS) - The DS contains the instrument's scientific measurements that are either measurement data sets (MDS) or annotation data sets (ADS). Further details are provided in the ASAR product specifications. All ASAR products are provided in ENVISAT format and are processed by the ESA PF-ASAR processor. For information on the latest version of PF-ASAR, see the Processor Releases page. The specifications for the ASAR data products currently made available by ESA are shown in the ASAR Product Table below. Detailed information on all ASAR products can be found in the ASAR Product Handbook. Product ID Product Name Nominal resolution (m - range x azimuth) Pixel Spacing (m) Coverage (km - range x azimuth) Equivalent No. Looks IMP_1P Image Mode Precision 30 x 30 12.5 56-100 x 100 >3 IMS_1P Image Mode Single-Look Complex 9 x 6 natural 56-100 x 100 1 IMM_1P Image Mode Medium resolution 150 x 150 75 56-100 x 100 40 APP_1P Alternating Polarisation Precision Image 30 x 30 12.5 41-106 x 100 >1.8 APS_1P Alternating Polarisation Single-Look Complex 9 x 12 natural 41-106 x 100 1 APM_1P Alternating Polarisation Medium resolution 150 x 150 75 41-106 x 100 50 WSM_1P Wide Swath Mode Medium resolution 150 x 150 75 400x 400 11.5 WSS_1P Wide Swath Mode Single-Look Complex 11.5-20 x 117 7.8x80 400x 400 1 GM1_1P Global Monitoring Mode Image 1000 x 1000 500 400x 400 7-9 WVI_1P Wave Mode Imagette and power spectrum 9 x 6 natural 5 x 5 1 WVS_1P Wave Mode Image Spectra - - 5 x 5 - WVW_2P Wave Mode Ocean Wave Spectra - - 5 x 5 - Table 1. ASAR L1 product types. *Range width depends on swath used. ASAR data products are currently available through a number of different sources: L0 and High resolution precision and single look complex (SLC) L1 IM, AP and WS products are available through the ESA Online Dissemination Service Medium resolution L1 IM, AP, WS and GM products are available through the EO Data Gateway and ESA Online Dissemination Service (OTF) L1 and L2 Wave products are available from the ESA Dissharm FTP server High Resolution products High resolution products are processed from the Level 0 data upon request using the On-The-Fly (OTF) service. These products are not archived but are processed when a product is selected, usually becoming available within a few minutes. The products processed in this manner are: ASA_IM__0P ASA_IMP_1P ASA_IMS_1P ASA_AP_0P (including Co-polar (APC), Cross-polar horizontal (APH) and Cross-polar vertical (APV)) ASA_APP_1P ASA_APS_1P ASA_WS__0P ASA_WSS_1P Once registered, users can access the Level 1 OTF standard service using the Online Dissemination Service. The Online Dissemination Service can be accessed here. To access products through the Online Dissemination Service users will need to log in using their ESA EO-SSO account. For more details on the OTF service, please see the ASAR OTF FAQ page. Medium Resolution products Medium resolution products are available through two different sources, which are as follows: During the operational lifetime of ASAR instrument, medium resolution products were processed operationally using the version of PF-ASAR available at the time of processing. More recently medium resolution products have also been processed from the Level 0 data during a bulk processing activity. Therefore, these products have been archived and are available for immediate download. The products available in this manner are: ASA_IMM_1P ASA_APM_1P ASA_WSM_1P ASA_GM1_1P Once registered, users can access the Level 1 products through the EO Data Gateway. To access products the EO Data Gateway users will need to log in using their ESA EO Sign In account. Additionally, the Medium Resolution Products for L1 IM, AP and WS can also be accessed from OTF service, in the same way as High Resolution Products. These products are not archived but are processed when a product is selected, usually becoming available within a few minutes. Wave products Wave products were processed operationally using the version of PF-ASAR available at the time of processing. Therefore, these products have been archived and are available for immediate download. The products available in this manner are: WVI_1P WVS_1P WVW_2P Once registered, users can access the Level 1 and Level 2 wave products though the ESA Dissharm FTP server (envwave-ftp-ds.eo.esa.int) using the credentials provided at registration. Information on ASAR Wave Mode data can be found in the 'Envisat ASAR Wave Mode Product Description and Reconstruction Procedure' document here. The purpose of this document is to provide the user community with information to reconstruct and interpret the ocean wave spectral information within the ASAR WV products.