HLSL30 v002

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.

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.