HLSS30 bands 4,3,2 showing croplands around Cedar Falls in Northeastern Iowa taken May 26, 2021.View full-size image
The Harmonized Landsat Sentinel-2 (HLS) project provides consistent surface reflectance data from the Operational Land Imager (OLI) aboard the joint NASA/USGS Landsat 8 satellite and the Multi-Spectral Instrument (MSI) 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 HLSS30 product provides 30-m Nadir Bidirectional Reflectance Distribution Function (BRDF)-Adjusted Reflectance (NBAR) and is derived from Sentinel-2A and Sentinel-2B MSI 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 HLSS30 product is provided in Cloud Optimized GeoTIFF (COG) format, and each band is distributed as a separate COG. There are 13 bands included in the HLSS30 product along with four angle bands and a quality assessment (QA) band. See the User Guide for a more detailed description of the individual bands provided in the HLSS30 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||2015-11-28 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||18|
|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||Red Edge1||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 6||Red Edge2||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 7||Red Edge3||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 8||NIR Broad||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 8A||NIR Narrow||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 9||Water Vapor||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 10||Cirrus||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 11||SWIR1||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|Band 12||SWIR2||N/A||16-bit signed integer||-9999||N/A||N/A||0.0001|
|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.
There are known issues regarding the Fmask band of this data product that impacts HLSS30 data prior to February 1, 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.
European Space Agency (ESA) started to add 1000 units to the scaled top of atmosphere (TOA) and surface reflectance in late January of 2022, and Interagency Implementation and Advanced Concepts Team (IMPACT) accordingly subtracts 1000 units after the TOA data is read. Users unaware of this change saw a jump in the time series.