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Crop Agriculture

Sentinel-2 Atmospheric Correction / SR Tutorial

(Sentinel-2 Atmospheric Correction/Surface Reflectance Tutorial & Imagery Downloads are Below)

GIS Ag Maps DOS Surface Reflectance Method (below downloads) for ArcGIS or other GIS software that can generate a Raster Attribute Table (band information included near bottom of page).

Sentinel-2 surface reflectance can be calculated with a downloadable toolkit; this tutorial shows how to convert to SR independently. Please see the following page for toolkit access information: Background information about USGS & GIS Ag Maps surface reflectance.

Related Pages: QGIS Sentinel-2 Surface Reflectance Tutorial    Landsat 8 / Sentinel-2 Rare Comparison & Data

Sentinel-2 is comprised of two satellites (2A & 2B) that produce free ongoing imagery with a combined revisit time of 5 days at the equator and 2 to 3 days at the mid-latitudes. Sentinel-2 has finer pixel resolution and more bands that Landsat (however, Landsat remains excellent data and the two can and should be used together). In order to convert to surface reflectance (SR), apply the steps in the Tutorial below. The method is a dark object subtraction (DOS; Chavez 1988, 1996) technique. Sentinel-2 Level 1C imagery can be downloaded from GloVis Next (opens in new tab). Contact us if you have any questions about applying the imagery.

Sentinel-2 Download Extent - Northwest Ohio (Eastern Corn Belt, USA; 7/19/16 (6.2 x 6.2 miles)

Sentinel-2 Atmospheric Correction/Surface Reflectance Tutorial & Imagery Download Extent

IMPORTANT: As is the case with Landsat, we have found that visible band, particularly the blue band, SR values become much less accurate at solar elevations less than 30⁰, but have not completed research for solar elevations from 30 to 50⁰. It is very likely that visible band retrieved SR becomes increasingly less accurate (too high) as solar elevations decrease from about 45⁰ - NIR AND SWIR BANDS REMAIN ACCURATE AT VERY LOW SOLAR ELEVATIONS. Chavez (1996) stated further research for the COST model (based on Landsat TM) is needed for solar elevations less than 35⁰ (solar zenith angles greater than 55⁰). CLICK HERE FOR LOW SOLAR ELEVATION IMAGERY DOWNLOADS.

Imagery Background & Tutorial Imagery Downloads

(Tutorial starts below downloads; more band information is included at bottom of page)

Naming convention for compressed zip file downloads below is as follows:

S2 is Sentinel-2 Satellite_Date_Band Number_Band Central Wavelength (based on chart below)_Band Description_ Band Resolution (meters). (Red edge is the vegetation spectral range where there is a steep increase from very low red reflectance [about 5%] to relatively high NIR reflectance [about 50%] - reflectance amounts can vary according plant and range boundaries may vary depending on the source.)

Pixel values represent Top of Atmosphere (TOA) reflectance units x 10,000 (for example, 0.50 TOA units correspond to a 5000 pixel value; .025 is 250).  

Please read prior to downloading: The downloaded compressed file name for the Composite Bands file starts with the number "0", bands 1-9 files start with the band number, while bands 10-12 files start will "B", then the band number - this was done simply as a way to have files ordered by band number on this page. Files decompress to original Sentinel-2 file name; see the following  page for Sentinel-2 image file naming convention: https://earth.esa.int/web/sentinel/user-guides/sentinel-2-msi/naming-convention. Images have level 1C processing and are .jp2 files, except for the Composite Band file which is a .tif file. The Composite Bands (band 11 [SWIR], band 8a [NIR], band 4 [red]) file was processed here with the bands that can be downloaded below - an image with the same band combination, but processed into a smaller image size, can be downloaded with Sentinel-2 imagery.