HLSL30 bands 4,3,2 showing Phoenix and the contrasting agricultural and desert landscape west of the city, May 2021.View full-size image
The Harmonized Landsat Sentinel-2 (HLS) project provides consistent surface reflectance (SR) and top of atmosphere (TOA) brightness data from a virtual constellation of satellite sensors. The Operational Land Imager (OLI) is housed aboard the joint NASA/USGS Landsat 8 and Landsat 9 satellites, while the Multi-Spectral Instrument (MSI) is mounted aboard Europe’s Copernicus Sentinel-2A and Sentinel-2B satellites. The combined measurement enables global observations of the land every 2–3 days at 30-meter (m) spatial resolution. The HLS project uses a set of algorithms to obtain seamless products from OLI and MSI that include atmospheric correction, cloud and cloud-shadow masking, spatial co-registration and common gridding, illumination and view angle normalization, and spectral bandpass adjustment.
The HLSL30 product provides 30-m Nadir Bidirectional Reflectance Distribution Function (BRDF)-Adjusted Reflectance (NBAR) and is derived from Landsat 8/9 OLI data products. The HLSS30 and HLSL30 products are gridded to the same resolution and Military Grid Reference System (MGRS) tiling system, and thus are “stackable” for time series analysis.
The HLSL30 product is provided in Cloud Optimized GeoTIFF (COG) format, and each band is distributed as a separate file. There are 11 bands included in the HLSL30 product along with one quality assessment (QA) band and four angle bands. See the User Guide for a more detailed description of the individual bands provided in the HLSL30 product.
Aerosol QA bits from the USGS Land Surface Reflectance Code (LaSRC) model output have been added into the Function of Mask (Fmask) data layer. The added two bits indicate the aerosol levels: high, medium, low, and climatology aerosol.
HLS surface reflectance products are currently at stage 1 validation. Stage 2 validation of the HLS products is ongoing and will be made available on the individual data product landing pages when complete.
|File Size||~20 MB|
|Temporal Extent||2013-04-11 to Present|
|Spatial Extent||Global (Non-Antarctic)|
|Coordinate System||Universal Transverse Mercator (UTM)|
|Datum||World Geodetic System (WGS84)|
|Geographic Dimensions||109.8 km x 109.8 km|
|Number of Science Dataset (SDS) Layers||15|
|Columns/Rows||3660 x 3660|
|Pixel Size||30 m|
|SDS Name||Description||Units||Data Type||Fill Value||No Data Value||Valid Range||Scale Factor|
|Band 1||Coastal Aerosol||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 2||Blue||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 3||Green||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 4||Red||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 5||NIR||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 6||SWIR1||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 7||SWIR2||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 9||Cirrus||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band10||TIRS1||N/A||16-bit signed integer||-9999||N/A||N/A||0.01|
|Band11||TIRS2||N/A||16-bit signed integer||-9999||N/A||N/A||0.01|
|Fmask||Quality Bits||Bit Field||8-bit unsigned integer||255||N/A||N/A||N/A|
|SZA||Sun Zenith Angle||Degree||16-bit unsigned integer||40000||N/A||N/A||0.01|
|SAA||Sun Azimuth Angle||Degree||16-bit unsigned integer||40000||N/A||N/A||0.01|
|VZA||View Zenith Angle||Degree||16-bit unsigned integer||40000||N/A||N/A||0.01|
|VAA||View Azimuth Angle||Degree||16-bit unsigned integer||40000||N/A||N/A||0.01|
Additional information related to cloud and aerosol quality along with QA mappings are provided under section 6.4 of the User Guide.
The atmospheric correction over bright targets occasionally retrieves unrealistically high aerosol and thus makes the surface reflectance too low. High aerosol retrievals, both false high aerosol and realistically high aerosol, are masked when quality bits 6 and 7 are both set to 1 (see Table 9 in the User Guide); the corresponding spectral data should be discarded from analysis.
For scenes greater than or equal to 80 degrees north, multiple overpasses can be gridded into a single MGRS tile resulting in an L30 granule with data sensed at two different times. In this same area, it is also possible that Landsat overpasses that should be gridded into a single MGRS tile are actually written as separate data files. Finally, for scenes with a latitude greater than or equal to 65 degrees north, ascending Landsat scenes may have a slightly higher error in the BRDF correction because the algorithm is calibrated using descending scenes.
There are known issues regarding the Fmask band of this data product that impacts HLSL30 data prior to April of 2022. The HLS Fmask data band may have omission errors in water detection for cases where water detection using spectral data alone is difficult, and omission and commission errors in cloud shadow detection for areas with great topographic relief. This issue does not impact other bands in the dataset.
There is a spike difference in HLSL30 and HLSS30 when generating NDVI index from granules after 2021 which was resolved with the integration of Landsat 9 in January 2023; however, it was not back processed. The HLS team is aware of this issue and is currently working on a fix.