USGS Landsat 7 Surface Reflectance Tier 2

LANDSAT/LE07/C01/T2_SR
Dataset Availability
1999-01-01T00:00:00Z - 2021-09-19T00:00:00
Dataset Provider
Earth Engine Snippet
ee.ImageCollection("LANDSAT/LE07/C01/T2_SR")
Tags
cfmask cloud fmask global landsat le07 ledaps reflectance sr usgs

Description

This dataset is the atmospherically corrected surface reflectance from the Landsat 7 ETM+ sensor. These images contain 4 visible and near-infrared (VNIR) bands and 2 short-wave infrared (SWIR) bands processed to orthorectified surface reflectance, and one thermal infrared (TIR) band processed to orthorectified brightness temperature. The VNIR and SWIR bands have a resolution of 30m / pixel. The TIR band, while originally collected with a resolution of 120m / pixel (60m / pixel for Landsat 7) has been resampled using cubic convolution to 30m.

These data have been atmospherically corrected using LEDAPS, and include a cloud, shadow, water and snow mask produced using CFMASK, as well as a per-pixel saturation mask.

Strips of collected data are packaged into overlapping "scenes" covering approximately 170km x 183km using a standardized reference grid.

Note that Landsat 7's orbit has been drifting to an earlier acquisition time since 2017.

See also the USGS page on SR QA bands.

SR can only be produced for Landsat assets processed to the L1TP level

Data provider notes:

  • SR is not run for a scene with a solar zenith angle greater than 76°.
  • Users are cautioned to avoid using SR for data acquired over high latitudes (> 65°).
  • The panchromatic band (ETM+ Band 7, OLI Band 8) is not processed to Surface Reflectance.
  • Efficacy of SR correction will be likely reduced in areas where atmospheric correction is affected by adverse conditions:
    • Hyper-arid or snow-covered regions
    • Low sun angle conditions
    • Coastal regions where land area is small relative to adjacent water
    • Areas with extensive cloud contamination

This product is generated by Google using a Docker image supplied by USGS.

Bands

Resolution
30 meters

Bands

Name Units Scale Wavelength Description
B1 0.0001 0.45-0.52 μm

Band 1 (blue) surface reflectance

B2 0.0001 0.52-0.60 μm

Band 2 (green) surface reflectance

B3 0.0001 0.63-0.69 μm

Band 3 (red) surface reflectance

B4 0.0001 0.77-0.90 μm

Band 4 (near infrared) surface reflectance

B5 0.0001 1.55-1.75 μm

Band 5 (shortwave infrared 1) surface reflectance

B6 Kelvin 0.1 10.40-12.50 μm

Band 6 brightness temperature. While originally collected with a resolution of 120m / pixel (60m / pixel for Landsat 7), this band has been resampled using cubic convolution to 30m.

B7 0.0001 2.08-2.35 μm

Band 7 (shortwave infrared 2) surface reflectance

sr_atmos_opacity 0.001

Atmospheric opacity; < 0.1 = clear; 0.1 - 0.3 = average; > 0.3 = hazy

sr_cloud_qa

Cloud quality attributes. Note: pixel_qa is likely to present more accurate results than sr_cloud_qa for cloud masking. See page 14 in the LEDAPS product guide.

pixel_qa

Pixel quality attributes generated from the CFMASK algorithm.

radsat_qa

Radiometric saturation QA

Image Properties

Image Properties

Name Type Description
CLOUD_COVER DOUBLE

Percentage cloud cover (0-100), -1 = not calculated. (Obtained from raw Landsat metadata)

CLOUD_COVER_LAND DOUBLE

Percentage cloud cover over land (0-100), -1 = not calculated. (Obtained from raw Landsat metadata)

EARTH_SUN_DISTANCE DOUBLE

Earth-Sun distance (AU)

ESPA_VERSION STRING

Internal ESPA image version used to compute SR

GEOMETRIC_RMSE_MODEL DOUBLE

Combined RMSE (Root Mean Square Error) of the geometric residuals (meters) in both across-track and along-track directions. (Obtained from raw Landsat metadata)

GEOMETRIC_RMSE_MODEL_X DOUBLE

RMSE (Root Mean Square Error) of the geometric residuals (meters) measured on the GCPs (Ground Control Points) used in geometric precision correction in the along-track direction. (Obtained from raw Landsat metadata)

GEOMETRIC_RMSE_MODEL_Y DOUBLE

RMSE (Root Mean Square Error) of the geometric residuals (meters) measured on the GCPs (Ground Control Points) used in geometric precision correction in the across-track direction. (Obtained from raw Landsat metadata)

IMAGE_QUALITY INT

Image quality, 0 = worst, 9 = best, -1 = quality not calculated. (Obtained from raw Landsat metadata)

LANDSAT_ID STRING

Landsat Product Identifier (Collection 1)

LEVEL1_PRODUCTION_DATE INT

Date of production for raw Level 1 data as ms since epoch

PIXEL_QA_VERSION STRING

Version of the software used to produce the 'pixel_qa' band

SATELLITE STRING

Name of satellite

SENSING_TIME STRING

Time of the observations as in ISO 8601 string. (Obtained from raw Landsat metadata)

SOLAR_AZIMUTH_ANGLE DOUBLE

Solar azimuth angle

SR_APP_VERSION STRING

LEDAPS version used to process surface reflectance

WRS_PATH INT

WRS path number of scene

WRS_ROW INT

WRS row number of scene

Terms of Use

Terms of Use

Landsat datasets are federally created data and therefore reside in the public domain and may be used, transferred, or reproduced without copyright restriction.

Acknowledgement or credit of the USGS as data source should be provided by including a line of text citation such as the example shown below.

(Product, Image, Photograph, or Dataset Name) courtesy of the U.S. Geological Survey

Example: Landsat-7 image courtesy of the U.S. Geological Survey

See the USGS Visual Identity System Guidance for further details on proper citation and acknowledgement of USGS products.

Explore in Earth Engine

/**
 * Function to mask clouds based on the pixel_qa band of Landsat SR data.
 * @param {ee.Image} image Input Landsat SR image
 * @return {ee.Image} Cloudmasked Landsat image
 */
var cloudMaskL457 = function(image) {
  var qa = image.select('pixel_qa');
  // If the cloud bit (5) is set and the cloud confidence (7) is high
  // or the cloud shadow bit is set (3), then it's a bad pixel.
  var cloud = qa.bitwiseAnd(1 << 5)
                  .and(qa.bitwiseAnd(1 << 7))
                  .or(qa.bitwiseAnd(1 << 3));
  // Remove edge pixels that don't occur in all bands
  var mask2 = image.mask().reduce(ee.Reducer.min());
  return image.updateMask(cloud.not()).updateMask(mask2);
};

var dataset = ee.ImageCollection('LANDSAT/LE07/C01/T2_SR')
                  .filterDate('2014-01-01', '2017-12-31')
                  .map(cloudMaskL457);

var visParams = {
  bands: ['B3', 'B2', 'B1'],
  min: 0,
  max: 3000,
  gamma: 1.4,
};
Map.setCenter(12.9261, -18.89, 11);
Map.addLayer(dataset.median(), visParams);