AST_L1T v003

ASTER Level 1 Precision Terrain Corrected Registered At-Sensor Radiance

Description

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Level 1 Precision Terrain Corrected Registered At-Sensor Radiance (AST_L1T) data contains calibrated at-sensor radiance, which corresponds with the ASTER Level 1B (AST_L1B), that has been geometrically corrected, and rotated to a north-up UTM projection. The AST_L1T is created from a single resampling of the corresponding ASTER L1A (AST_L1A) product. The bands available in the AST_L1T depend on the bands in the AST_L1A and can include up to three Visible and Near Infrared (VNIR) bands, six Shortwave Infrared (SWIR) bands, and five Thermal Infrared (TIR) bands. The AST_L1T dataset does not include the aft-looking VNIR band 3.

The precision terrain correction process incorporates GLS2000 digital elevation data with derived ground control points (GCPs) to achieve topographic accuracy for all daytime scenes where correlation statistics reach a minimum threshold. Alternate levels of correction are possible (systematic terrain, systematic, or precision) for scenes acquired at night or that otherwise represent a reduced quality ground image (e.g., cloud cover).

For daytime images, if the VNIR or SWIR telescope collected data and precision correction was attempted, each precision terrain corrected image will have an accompanying independent quality assessment. It will include the geometric correction available for distribution in both as a text file and a single band browse images with the valid GCPs overlaid.

This multi-file product also includes georeferenced full resolution browse images. The number of browse images and the band combinations of the images depends on the bands available in the corresponding AST_L1A dataset.

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Characteristics

Collection and Granule

Collection

Characteristic Description
CollectionTerra ASTER
DOI10.5067/ASTER/AST_L1T.003
File Size~115 MB
Temporal ResolutionOther
Temporal Extent2000-03-04 to Present
Spatial ExtentGlobal
Coordinate SystemUniversal Transverse Mercator (UTM)
DatumWorld Geodetic System (WGS84)
File FormatHDF-EOS or GeoTIFF
Geographic Dimensions~60 km x 60 km

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers14
Columns/RowsVaries by scene x Varies by scene
Pixel Size15 m (VNIR), 30 m (SWIR), and 90 m (TIR)

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
VNIR_Band1 15 meter resolution VNIR Band 1(0.52 to 0.60 µm) W/m²/sr/μm 8-bit unsigned integer N/A N/A 0 to 255 N/A
VNIR_Band2 15 meter resolution VNIR Band 2 (0.63 to 0.69 µm) W/m²/sr/μm 8-bit unsigned integer N/A N/A 0 to 255 N/A
VNIR_Band3N 15 meter resolution VNIR Band 3N (0.78 to 0.86 µm) W/m²/sr/μm 8-bit unsigned integer N/A N/A 0 to 255 N/A
SWIR_Band4 30 meter resolution SWIR Band 4 (1.600 to 1.700 µm) W/m²/sr/μm 8-bit unsigned integer N/A N/A 0 to 255 N/A
SWIR_Band5 30 meter resolution SWIR Band 5 (2.145 to 2.185 µm) W/m²/sr/μm 8-bit unsigned integer N/A N/A 0 to 255 N/A
SWIR_Band6 30 meter resolution SWIR Band 6 (2.185 to 2.225 µm) W/m²/sr/μm 8-bit unsigned integer N/A N/A 0 to 255 N/A
SWIR_Band7 30 meter resolution SWIR Band 7 (2.235 to 2.285 µm) W/m²/sr/μm 8-bit unsigned integer N/A N/A 0 to 255 N/A
SWIR_Band8 30 meter resolution SWIR Band 8 (2.295 to 2.365 µm) W/m²/sr/μm 8-bit unsigned integer N/A N/A 0 to 255 N/A
SWIR_Band9 30 meter resolution SWIR Band 9 (2.360 to 2.430 µm) W/m²/sr/μm 8-bit unsigned integer N/A N/A 0 to 255 N/A
TIR_Band10 90 meter resolution TIR Band 10 (8.125 to 8.475 µm) W/m²/sr/μm 16-bit unsigned integer N/A N/A 0 to 65535 N/A
TIR_Band11 90 meter resolution TIR Band 11 (8.475 to 8.825 µm) W/m²/sr/μm 16-bit unsigned integer N/A N/A 0 to 65535 N/A
TIR_Band12 90 meter resolution TIR Band 12 (8.925 to 9.275 µm) W/m²/sr/μm 16-bit unsigned integer N/A N/A 0 to 65535 N/A
TIR_Band13 90 meter resolution TIR Band 13 (10.25 to 10.95 µm) W/m²/sr/μm 16-bit unsigned integer N/A N/A 0 to 65535 N/A
TIR_Band14 90 meter resolution TIR Band 14 (10.95 to 11.65 µm) W/m²/sr/μm 16-bit unsigned integer N/A N/A 0 to 65535 N/A

Full Resolution Image (GeoTIFF) color composite band combinations¹

TIF Bands Available Red band Green band Blue band
_V.tif 15 meter resolution VNIR (bands 1, 2, 3N) and resampled 15 meter resolution pre-April 2008 SWIR (band 4) 4 3N 2
_V.tif 15 meter resolution VNIR only (bands 1, 2, 3N) 2 3N 1
_T.tif 90 meter resolution TIR (bands 10, 12, 14) 14 12 10

¹Reduced resolution browse thumbnail images assume the same band combination and spatial resolution as their full resolution counterparts; Visible Infrared Full Resolution Images are 15 meters and Thermal Infrared Full Resolution Images are 90 meters.

QA Report Text File (when produced)²

Report sections Information contained in report sections
GLS 2000 Ground Control Points (GCPs) used to correct the scene Listing of GCPs
Summarized correlation of comparison GCPs pixel offset from AST_L1T to a GLS2000 Standard Scene. Mean, median, standard deviation
Quadrant RMSE Mean, median, standard deviation
Full scene RMSE Mean, median, standard deviation

²Refer to ASTER Level 1T User Guide for additional information on the Quality Assurance Files.

Quality Assessment browse (JPEG)

Color Code Range for the number of pixels off nominal
Red >3 pixels
Yellow ≤ 3 and > 2
Blue ≤ 2 and > 1
Cyan ≤ 1 and > 0.5
Green ≤ 0.5 pixel

Known Issues

A modification has been incorporated within the processing of the AST_L1T data product for correcting zero-filled scans that appear in the processing of low-latitude, ascending orbit (night) thermal infrared (TIR) data acquisitions. This correction has been implemented for the historical archive of the ASTER L1T data product and for newly processed scenes as of October 1, 2017. Additional information can be found in the ASTER L1T User Advisory for more details.

Users are advised that ASTER SWIR data acquired from April 2008 to the present exhibit anomalous saturation of values and anomalous striping. This effect is also present for some prior acquisition periods. Please refer to the ASTER SWIR User Advisory Document for more details.

Documentation

Using the Data

E-Learning

R You Ready to Python? An Introduction to Working with Land Remote Sensing Data in R and Python

Working with Land Remote Sensing Data in a GIS Environment

Working with ASTER L1T Visible and Near Infrared (VNIR) Data in R

Observing Land from Space: Interacting with Geospatial Data from NASA's LP DAAC

View from NASA Terra's Zoom Lens: All About the ASTER Sensor

Data In Action

Observing Superstorm Sandy with VIIRS and ASTER Data: A 5 Year Review

A View from Above: The Aftermath of a Tornado

ASTER: The Ultimate 2018 Winter Olympics Observer

Global Land Ice Measurements from Space: Observing Glaciers Using ASTER

Highlights from the Literature: January to March 2016

Will Cape Town Run Out of Water?

When there’s a disaster, look for ASTER

Highlights from the Literature: October to December 2018

Highlights from the Literature: January to March 2019

ECOSTRESSED: Measuring Temperatures of Cities During Extreme Heatwaves

Evolution of a Wildfire

Access Data

Citation

DOI: 10.5067/ASTER/AST_L1T.003

About the Image

Terra ASTER level 1 precision terrain corrected registered at-sensor radiance band combination 3n-1-3n data from the AST_L1T product over Guatemala on January 8, 2018.

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