USGS Landsat 4 Surface Reflectance Tier 1

LANDSAT/LT04/C01/T1_SR
Dataset Provider
Earth Engine Snippet
ee.ImageCollection("LANDSAT/LT04/C01/T1_SR")
Tags
global sr reflectance ledaps cloud fmask cfmask lt04 landsat usgs

Description

This dataset is the atmospherically corrected surface reflectance from the Landsat 4 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.

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 23 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 INT

Percentage cloud cover, -1 = not calculated

CLOUD_COVER_LAND INT

Percentage cloud cover over land, -1 = not calculated

IMAGE_QUALITY INT

Image quality, 0 = worst, 9 = best, -1 = quality not calculated

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_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 across-track direction. (Obtained from raw Landsat metadata)

EARTH_SUN_DISTANCE DOUBLE

Earth-Sun distance (AU)

ESPA_VERSION STRING

Internal ESPA image version used to compute SR

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

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

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/LT04/C01/T1_SR')
                  .filterDate('1989-01-01', '1992-12-31')
                  .map(cloudMaskL457);

var visParams = {
  bands: ['B3', 'B2', 'B1'],
  min: 0,
  max: 3000,
  gamma: 1.4,
};
Map.setCenter(-114.6588, 31.6569, 10);
Map.addLayer(dataset.median(), visParams);

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