1 ASTER 介绍
Advanced Spaceborne Thermal Emission and Reflection Radiometer 星载热量散发和反辐射仪
The Advanced Spaceborne Thermal Emission and Reflection Radiometer obtains high-resolution (15 to 90 square meters per pixel) images of the Earth in 14 different wavelengths of the electromagnetic spectrum, ranging from visible to thermal infrared light. Scientists use ASTER data to create detailed maps of land surface temperature, emissivity, reflectance, and elevation.
波段分布
| 波段编号 | 波段类型 | 波长范围(微米) | 侧视角（°） | 分辨率（米） |
| B1 | 可见光近红外波段 | 0.52～0.60 | +/-24 | 15 |
| B2 | 可见光近红外波段 | 0.63～0.69 | +/-24 | 15 |
| B3 | 可见光近红外波段 | 0.76～0.86 | +/-24 | 15 |
| 立体后视 | 可见光近红外波段 | 0.76～0.86 | +/-24 | 15 |
| B4 | 短波红外 | 1.60～1.70 | +/-8.55 | 30 |
| B5 | 短波红外 | 2.145～2.185 | +/-8.55 | 30 |
| B6 | 短波红外 | 2.185～2.225 | +/-8.55 | 30 |
| B7 | 短波红外 | 2.235～2.285 | +/-8.55 | 30 |
| B8 | 短波红外 | 2.295～2.365 | +/-8.55 | 30 |
| B9 | 短波红外 | 2.360～2.430 | +/-8.55 | 30 |
| B10 | 热红外 | 8.125～8.475 | +/-8.55 | 90 |
| B11 | 热红外 | 8.475～8.825 | +/-8.55 | 90 |
| B12 | 热红外 | 8.925～9.275 | +/-8.55 | 90 |
| B13 | 热红外 | 10.25～10.95 | +/-8.55 | 90 |
| B14 | 热红外 | 10.95～11.65 | +/-8.55 | 90 |
The ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) sensor is an imaging instrument flown on the Terra satellite which was launched in December 1999. ASTER has been designed to acquire land surface temperature, emisivity, reflectance, and elevation data and is a cooperative effort between NASA and the Japanese Ministry of Economy, Trade, and Industry (METI). As of April 1, 2016 these date are being distributed free of charge.
| Resolution | VNIR 15 m SWIR 30 m TIR 90 m |
|---|---|
| Nominal Swath Width | 60 km |
| Bands |
|
| Archive Availability | Possible from 1999 |
| Programmable? | No |
| Minimum area of purchase | Standard, full scenes only |
| Stereo available? | Yes along track stereo from Level 1A VNIR bands 3N and 3B |
| Largest Scale | 1:40,000 - VNIR & SWIR |
| Bit depth | 8 bits VNIR & SWIR 12 bits TIR |
An ASTER scene covers an area of approximately 60 km by 60 km and data is acquired simultaneously at three resolutions.
VNIR - 15m spatial resolution - 3 bands at Green, Red, and Near InfraRed wavelengths
- for the AST_L1B dataset only, there is also a backward viewing band 3B.
SWIR - 30m spatial resolution - 6 bands between 1.65 and 2.40 micrometers
TIR - 90m spatial resolution - 5 bands between 8.29 and 11.13 micrometers
Note: Since April 2008 the ASTER SWIR sensor has been subjected to abnormally high temperature abnormalities and these bands should not be used. The VNIR and TIR data are fine.
The images are georeferenced to the WGS-84 datum and Universal Transverse Mercator projection. Data are acquired when tasked and the telescopes on the ASTER sensor can be pointed to each side to expand data collection opportunities. As a result, images do not have regular and repeating path and row footprints as many other sensors have. This can provide a challenge when searching for imagery over time.
As of the spring of 2016 the primary full ASTER individual dataset is the AST_L1T: ASTER Level 1 Precision Terrain Corrected Registered At-Sensor Radiance product. The AST_L1T product has a very high level of geometric correction and the scenes are distributed with a North-Up orientation. All prior ASTER scenes have been reprocessed to this data format. A complete ASTER scene consists of 14 bands of data as described above. In addition you can select full resolution browse images in GeoTIFF format suitable for use in GIS programs along with several Quality Assurance files. You should read the USGS AST_L1T product page for full dataset details.
The earlier ASTER version AST_L1B: ASTER Level 1B Registered Radiance at the Sensor product includes the backward viewing NIR band labeled 3B and is delivered in the along-track orientation. These scenes should be rotated so north is up.
There are several ASTER products derived from individual scenes such as temperature, emissivity, and reflectance. You can view the full list of products, as well as individual product documentation sheets at: https://lpdaac.usgs.gov/dataset_discovery/aster/aster_products_table.
| Short Name | Collection | Keyword | Spatial Resolution (m) | Temporal Resolution |
|---|---|---|---|---|
| AST14DEM.003 | Terra ASTER | Elevation | 30 | Other |
| AST14DMO.003 | Terra ASTER | Elevation, Surface Radiance | 15, 30, 90 | Other |
| AST14OTH.003 | Terra ASTER | Surface Radiance | 15, 30, 90 | Other |
| ASTGTM.003 | Terra ASTER | Elevation | 30 | Multi-Year |
| ASTGTM.002 | Terra ASTER | Elevation | 30 | Multi-Year |
| ASTWBD.001 | Terra ASTER | Elevation, Land Cover | 30 | Multi-Year |
| AST_05.003 | Terra ASTER | Emissivity | 90 | Other |
| AST_07.003 | Terra ASTER | Surface Reflectance | 15, 30 | Other |
| AST_07XT.003 | Terra ASTER | Surface Reflectance | 15, 30 | Other |
| AST_08.003 | Terra ASTER | Land Surface Temperature (LST) | 15 | Other |
| AST_09.003 | Terra ASTER | Surface Radiance | 15, 30 | Other |
| AST_09T.003 | Terra ASTER | Surface Radiance | 90 | Other |
| AST_09XT.003 | Terra ASTER | Surface Radiance | 15, 30 | Other |
| AST_L1A.003 | Terra ASTER | Unprocessed | 15, 30, 90 | Other |
| AST_L1AE.003 | Terra ASTER | Unprocessed | 15, 30, 90 | Other |
| AST_L1B.003 | Terra ASTER | Surface Radiance | 15, 30, 90 | Other |
| AST_L1BE.003 | Terra ASTER | Surface Radiance | 15, 30, 90 | Other |
| AST_L1T.003 | Terra ASTER | Surface Radiance | 15, 30, 90 | Other |
Each product has unique scaling factors and fill values that are described in the product documentation. For example, the AST_08 Surface Kinetic Temperature product has a valid data range from 200 to 3200 and must be multiplied by 0.1 to restore the values to degrees Kelvin.
Note: If you are considering working with the AST_07: ASTER Surface Reflectance VNIR and SWIR product prior to April 2008, you may want to consider using the AST_07XT: ASTER Surface Reflectance VNIR and Crosstalk Corrected SWIR product instead. One SWIR band has defective shielding, leading to light leakage to other SWIR bands. This is referred to as Crosstalk. An algorithm has been developed to remove this aberration.
ASTER is a multispectral imager which flies on EOS-Terra polar orbiting platform with four other sensors. EOS-Terra was launched in Jun. 2000. ASTER covers a wide spectral region from visible to thermal infrared by 14 spectral bands with high spatial and spectral and radiometric resolutions. ASTER stands for the Advanced Spaceborne Thermal Emission and Reflection radiometer. The EOS-Terra orbit is a circular, near polar orbit at 705 km altitude. The orbit is sun-synchronous with a local time of 10:30 a.m. The recurrent cycle is 16 days. Thus, the orbit parameters are the same as Landsat.
The main purpose of the science investigation by ASTER is to study the interaction among the geosphere, hydrosphere, cryosphere, and atmosphere of the Earth. The target area of the science investigation are (a) geology and soil, (b) volcano monitoring, (c) carbon cycle and marine ecosystem, (d) aerosol and cloud, (e) evapotranspiration, (f) hydrology, (g) vegetation and ecosystem dynamics, and (h) land surface climatology.
参考：
https://terra.nasa.gov/about/terra-instruments/aster
https://www.sciencedirect.com/topics/earth-and-planetary-sciences/aster
https://yceo.yale.edu/what-aster
https://rs-freedatasource.readthedocs.io/zh_CN/latest/ASTER.html