Introduction to Envisat satellite and ASAR data

Summary: The Envisat satellite, one of the ESA satellite-to-ground observation satellites, was launched on March 1, 2002. The satellite is the largest environmental satellite ever built in Europe. The star is loaded with 10 detection devices, 4 of which are improved by the ER s-1/2 device, the largest of which is advanced synthetic aperture Radar (ASAR), which generates oceans, coasts, polar ice caps and ...

The Envisat satellite, one of the ESA satellite-to-ground observation satellites, was launched on March 1, 2002. The satellite is the largest environmental satellite ever built in Europe. The star is loaded with 10 detection devices, 4 of which are improved by the ER S-1/2, the largest of which is the advanced Synthetic Aperture Radar (ASAR), which generates high-quality images of oceans, coasts, polar ice caps and land, and provides scientists with higher resolution images to study the changes in the oceans. Other devices will provide higher-precision data for studying the Earth's atmosphere and atmospheric density.   As a continuation of the ERS-1/2 Synthetic Aperture Radar (SAR) satellite, ENVISAT-1 data is mainly used for monitoring the environment, i.e. continuous observation of the Earth's surface and atmosphere for mapping, resource exploration, meteorological and disaster judgment. The main parameters of the satellite are as follows:

Launch time

March 1, 2002 (Central Europe Time)

Vehicle

Ariana No. 5th Rocket

Emission weight

8200 kg

Payload Weight (instrument)

2050 kg

Design Life

5 years ~ 10

Number of instruments on the star

10

Track

Sun Sync, height 800 km

Orbital inclination

98°

Single lap time

101 minutes

Repeat cycle

35 days

Cost

About 2 billion euros

Major participating countries

Austria, Belgium, Canada, Denmark, France, Finland, Germany, Italy, Norway, Spain, Sweden, Switzerland, the Netherlands and the United Kingdom

Asar is a high-resolution test imaging radar loaded by ENVISAT, operating at the C-band, which covers ocean wave studies, sea-ice range and motion studies, land surface research and monitoring of the environment and climate change. The advantages of the data include large coverage of radar data, multi-polarization mode, multiple incident angle and flexible operation mode. 5 working modes of ASAR data: Table One:

Measurement mode

Function description

Image mode

Polarization mode: VV or hh,7 selectable bandwidth (56-100km), spatial resolution 30m

Polarization mode

2 registration images per acquisition, 7 selectable bandwidths, HH/VV, HH/HV, HH/VH spatial resolution approx. 30m

Bandwidth mode

One King 400km*400km, spatial resolution 150M,VV or HH polarization mode

Global Monitoring model

Spatial resolution 1000m, covering the entire track, VV or HH polarization

Wave mode

Data is in the form of small pattern, 10km5km or 5km5km, 100km,vv or HH polarization, can be converted into a wave spectrum, mainly used for marine monitoring

Asar data at all levels of data products: Table II:

Working mode

Level-0 Data Products

LEVEL-1B Data Products

Image mode

ASAIM0P

AsaIMP1P (fine image) AsaIMS1P (single view complex image) AsaIMG1P (ellipsoid geocoding) AsaIMM1P (medium resolution image)

Polarization mode

AsaAPC0P (polarized mode HH/VV) ASAAPV0P (Polarized way VV/VH) ASAAPH0P (polarization mode HH/HV)

AsaAPP1P (fine image) AsaAPG1P (ellipsoid geocoding image) AsaAPM1P (mid-resolution image) ASAAPS1P (complex image)

Bandwidth mode

ASAWS0P (bandwidth mode)

ASAWSM1P (standard image)

Global Monitoring model

ASAGM0P (Global monitoring mode)

ASAGMI1P (image)

Wave mode

ASAWV0P (wave mode)

AsaWVI1P (fine image) AsaWVS1P (complex image)

Level 0 Products: This level of product is reformatted, time-stored satellite data, for the lowest level of Envisat PDS products, from the original data, can be processed in any other software, mainly for the testing of SAR processors, or the entire data processing process of the SAR. 1 Class B Products: This grade product is a geo-positioning Engineering Foundation product, data has been converted into engineering units, auxiliary data separated from the measurement data, and the data have a selective calibration. This product is the basis for more advanced products. 1B products are obtained from the level 0 products, a total of 3 forms: (1) unconfirmed. The product is produced in a quasi-real-time manner for monitoring the instrument. The product is obtained using quasi-real-time auxiliary data (i.e., no accurate orbital vectors or calibration data). (2) Fully substantiated. Offline generation, sorted by time, no overlap, no data gaps, fully validated. Is the basis for further off-line processing. Use the most accurate auxiliary data generation. (3) partially confirmed. The product simply does not use the most accurate auxiliary data for processing.    as shown in table 2, there are mainly the following products in each mode: (1) fine images (precision image). The product is a multi-view, ground-distance digital image (vv or HH). Can be used for multi-temporal analysis and can be used to obtain a backscatter coefficient. The known system error is corrected. The absolute calibration parameters are stored in the product notes. (2) ellipsoid geocoding image (ellipsoid geocoded image). The product is similar to a fine image, except that it has been projected by the map. The absolute calibration parameters are stored in the product notes. (3) Single-View complex image (Single-look complex). This product is used for quality evaluation, calibration, generation of interferometric images of SAR image, or application of wind/wave. The product is less correct and interpolated to ensure greater freedom when producing more advanced products. The absolute calibration parameters are stored in the product notes. (4) Medium resolution images (medium-resolution image). The product is available in a resolution of M, which is used primarily for sea ice and oceanographic applications. The absolute calibration parameters are stored in the product notes. Asar also has two auxiliary modes (Testmodes and Module Steppingmode) and a calibration mode (external characterization mode) data type, which is used for testing, calibration, and instrument monitoring, not listed here.    Another classification method divides Asar data products into image products and wave mode products. In the image product, it can also be divided into image products (striplineprocessed image product) and landscape images producedProducts (stand-alone imageproduct). With image product coverage size range is a complete scan band or a whole track (such as global monitoring mode), and ensure the product coverage of the geometry and radiation continuity; Landscape image products can be extracted from the image products. The size of the landscape image is based on granule as the basic unit. Landscape image products are produced according to user needs, can be directly from the 0-level products, including: Image mode single-view complex map (ASAIMS1P), Image mode fine view (ASAIMP1P), image mode ellipsoid geocoding map (ASAIMG1P), polarization mode single view complex (ASAAPS1P) and polarization mode fine maps (ASAAPP1P); polarized mode ellipsoid geocoding map (ASAAPG1P) with image products including all mid-resolution image products and browse image products. Compared with other SAR satellites, ENVISAT satellites have multi-polarization characteristics. The HH product of the image mode can be applied in geology, sea-testing, VV or HH products can be used in snow melting, crop conditions, earthquake/volcano/land subsidence, ice/ice movement and other monitoring; Alternating polarisation model VV/VH products can be applied in agriculture, forestry, hydrology, land cover, soil moisture and other aspects, HH/HV products can be used in urban mapping, ship detection, VV/HH products can be applied in oceanography, marine meteorology, coastal phenomena, Surface characteristics, etc.; Wide SWATH model HH products can be used in oceanography, sea ice range monitoring, flood monitoring, etc., VV products can be used in pollution monitoring, land moisture estimation, marine meteorology, VV or HH products can be used in vegetation mapping, ice range and melting zone. Asar naming rules for data:

General the name of the file is something like:

ASAIMS1ppipa200504020955560000001620360006516151_0388.n1

ASA = Sensor--asar Sensor IMS = = mode and product (image mode, SLC product)-imaging mode, many kinds, ws,wss,im, ... 1PPIPA = order number, not interesting--custom 20050402 = date--Data acquisition time--UTC time _095556 = IMPORTANT ! This is the start time (it's not a exactly what do you see in Eoli SA, and you just need to know it roughly so that you know th E area) 000000162036 = Some Kind of code, not interesting 00065 = Track--enviview The explanation given is Relati ve orbit 16151 = Orbit--absolute orbit 0388 = Some Kind of code, not interesting

Introduction to Envisat satellite and ASAR data