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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 ASAR WM Ocean Wave Spectra L2 [ASA_WVW_2P]
The ASAR Wave Mode product is created by inverting the cross-spectra which is computed from inter-look processing of the SLC wave imagettes in order to derive the directional ocean product ocean wave spectra. Auxiliary ADSs included with the product remains the same as for the ASAR Wave Mode Cross-Spectra product. The output follows the format of the Envisat ASAR Level 1B Wave Mode Imagette Cross-Spectra (ASA_WVS_1P) product. This is done in order to be compatible with the ground segment products of Envisat ASAR. This product provides a continuation of the ERS-SAR wave mode data. Output: Wavelength range from 20 to 1000 m in 24 logarithmic steps.
Envisat ASAR Wave Imagette Cross Spectra L1 [ASA_WVS_1P]
The ASAR Wave product is extracted from the combined SLC and Cross Spectra product, ASA_WVI_1P, which is generated from data collected when the instrument was in Wave Mode using the Cross Spectra methodology. The product is meant for Meteo users. The spatial coverage is up to 20 spectra acquired every 100 km, with a minimum coverage of 5km x 5km. The file size has a maximum of 0.2 Mbytes. Auxiliary data include Orbit state vector, Time correlation parameters, Wave Processing parameters ADS, Wave Geolocation ADS, SQ ADS. The product provides a continuation of the ERS-SAR wave mode data. Output: Wavelength range from 20 to 1000 m in 24 logarithmic steps.
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 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 WS Single Look Complex L1 [ASA_WSS_1P]
The Level-1B data product offered by ESA from the ASAR Wide-Swath Mode (WS) is a multi-look detected product, ASA_WSM_1P, intended to support applications that exploit intensity data. In order to support the development of new applications with the ASAR ScanSAR data, a WSM product providing phase information has been developed and implemented in the ESA ASAR processor - the Wide-Swath Single-Look complex product (ASA_WSS_1P). This product is mainly used for INSAR applications based either on wide-swath/wide-swath pairs or wide-swath/image mode pairs, applications of ocean current mapping, large-area ocean wave retrievals and atmospheric water vapour characterisation. It is important to mention that the standard ESA WSS product is based on the prototype WSS processor developed by Polimi/Poliba, which has also been used to generate prototype products for testing potential and preparing the exploitation of the WSS product. The ESA ASA_WSS_1P product is available as a standard Envisat ASAR product. The ASA_WSS_1P product format is slightly different from other ASAR products since: There are 5 different MDSs, one per sub-swath A "Doppler Grid" ADS has been included to support ocean current mapping applications There are 5 records in the MPP ADS, one per sub-swath There are 5 records in the SQ ADS, one per sub-swath. Other key characteristics of the ASA_WSS_1P product are summarised below: Processing is fully phase preserving Data in the MDSs is sampled in a common grid both in range and in azimuth Standard product is 60 sec long with 80 m az. pixel spacing Auxiliary timeline information has been added in the Main Processing Parameters ADS Elevation antenna pattern correction is applied by default (although the product is a single-look complex). Spatial Resolution: Approximately 8 m slant range x 80 m azimuth.
Envisat ASAR Wave SLC and Cross-Spectra Imagettes L1 [ASA_WVI_1P]
This is the basic Level 1B ASAR Wave Mode product, including up to 400 single-look, complex, slant range, imagettes generated from Level 0 data and up to 400 imagette power spectra computed using the cross-spectra methodology. The auxiliary parameters used are the most up-to-date at the time of processing. A minimum number of corrections and interpolations are performed in order to allow the end-user maximum freedom to derive higher level products. Complex output data is retained to avoid loss of information. Absolute calibration parameters, when available (depending on external calibration activities), are provided in the product annotations. Imagette power spectrum is equivalent to the ERS UWA (Near Real Time) product with revisited algorithm (cross-spectra) taking into account the higher quality of the SLC imagette. Note that starting from an SLC imagette, the generation of an ERS UWA-type product might be ensured by a simple look detection and summation. This product provides a continuation of the ERS-SAR wave mode data. Imagette Spatial Resolution: 20 m ground range x 20 m azimuth. Cross Spectra Output: Wavelength range from 20 to 1000 m in 24 logarithmic steps.
Envisat ASAR IM Precision L1 [ASA_IMP_1P]
This is a multi-look, ground range, digital Precision Image generated from Level 0 data collected when the instrument was in Image Mode (7 possible swaths HH or VV polarisation). The product includes slant range to ground range correction. It is for users wishing to perform applications-oriented analysis and applies to multi-temporal imaging and to derive backscattering coefficients. The stand-alone image is generated using the Range/Doppler algorithm. The processing uses up to date (at time of processing) auxiliary parameters corrected for antenna elevation gain, and range spreading loss. Engineering corrections and relative calibration are applied to compensate for well-understood sources of system variability. Absolute calibration parameters, when available (depending on external calibration activities) are provided in the product annotations. This product provides a continuation of the ERS-SAR_PRI product. Spatial Resolution: 30 m ground range x 30 m azimuth.
Envisat ASAR AP Single-Look Complex L1 [ASA_APS_1P]
This product is a complex, slant-range, digital image generated from Level 0 data collected when the instrument is in Alternating Polarisation mode. (7 possible swaths). It contains two CO-registered images corresponding to one of the three polarisation combination submodes (HH and VV, HH and HV, VV and VH). In addition, the product uses the Range Doppler algorithm and the most up to date processing parameters available at the time of processing. It can be used to derive higher level products for SAR image quality assessment, calibration and interferometric applications, if allowed by the instrument acquisition. A minimum number of corrections and interpolations are performed on the data in order to allow the end-user maximum freedom to derive higher level products. Complex output data is retained to avoid loss of information. Absolute calibration parameters are available depending on external calibration activities and are provided in the product annotations. Spatial Resolution: Approximately 8m slant range x approximately 4m azimuth.
Envisat ASAR WS L0 [ASA_WS__0P]
The WS Mode Level 0 product consists of time-ordered AISPs collected while the instrument was is in Wide Swath Mode. The echo samples in the AISPs have been compressed to 4 bits per sample using FBAQ. This is a high-rate, wide swath (ScanSAR) mode so data is only acquired for partial orbit segments and is composed from five image swaths (SS1 to SS5). The Level 0 product is produced systematically for all data acquired within this mode. The objective of this product is to offer Level 0 data for possible image processing on another processing site. It includes mandatory information for SAR processing. Data Size: 400 km across track x 400 km along track.
Envisat ASAR WS Medium Resolution L1 [ASA_WSM_1P]
The strip-line product has been generated from Level 0 data collected when the instrument was in Wide Swath Mode. The product includes slant range to ground range corrections and covers a continuous area along the imaging swath. It is intended to perform application oriented analysis on large scale phenomena over a wide region and for multi-temporal imaging. This is the standard product for ASAR Wide Swath Mode. The ASAR WS L0 full mission data archive has been bulk processed to Level 1 (ASA_WSM_1P) in Envisat format with the IPF-ASAR processor Version 6.03. Spatial Resolution: 150 m slant range x 150 m 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.
Envisat ASAR IM L0 [ASA_IM__0P]
The ASAR Image Mode source packets Level 0 data product offers Level 0 data for possible images processing on an other processing site. It includes some mandatory information for SAR processing. The Image Mode Level 0 product consists of time-ordered Annotated Instrument Source Packets (AISPs) collected by the instrument in Image Mode. The echo samples contained in the AISPs are compressed to 4 bits/sample using Flexible Block Adaptive Quantisation (FBAQ). This is a high-rate, narrow swath mode so data is only acquired for partial orbit segments and may be from one of seven possible image swaths. The Level 0 product is produced systematically for all data acquired within this mode. This product provides a continuation of the ERS-SAR_RAW product.
Envisat ASAR IM Medium Resolution L1 [ASA_IMM_1P]
This ASAR Medium Resolution strip-line product has been generated from Level 0 data collected when the instrument was in Image Mode. This product has lower resolution but higher radiometric resolution than the ASA_IMP. It is intended to perform applications-oriented analysis on large scale phenomena and multi-temporal imaging. This product provides a continuation of the ERS-SAR Image Mode data. The ASAR IM L0 full mission data archive has been bulk processed to Level 1 (ASA_IMM_1P) in Envisat format with the IPF-ASAR processor Version 6.03. Spatial Resolution: 150 m ground range x 150 m azimuth.
Envisat ASAR AP Precision L1 [ASA_APP_1P]
This ASAR Alternating Polarisation Mode Precision product is generated from Level 0 data collected when the instrument is in Alternating Polarisation Mode (7 possible swaths). The product contains two CO-registered images corresponding to one of the three polarisation combination submodes (HH and VV, HH and HV, VV and VH). This is a stand-alone multi-look, ground range, narrow swath digital image generated using the SPECAN algorithm and the most up to date auxiliary information available at the time of processing. Engineering corrections and relative calibration (antenna elevation gain, range spreading loss) are applied to compensate for well-understood sources of system variability. Generation of this product uses a technique to allow half the looks of an image to be acquired in horizontal polarisation and the other half in vertical polarisation and processed to 30-m resolution (with the exception of IS1). Absolute calibration parameters are available depending on external calibration activities and are provided in the product annotations. Spatial Resolution: 30 m ground range x 30 m azimuth.