Towards Seamless Global 30-meter Terrestrial Monitoring: Evaluating 2022 Cloud Free Coverage of Harmonized Landsat and Sentinel-2 (HLS) V2.0

Global observations at 30 m ground sampling distance (GSD) are now possible at a cadence of 1-3 days by combining Landsat 8 and 9 and Sentinel-2A and -2B satellites, but currently little information exists about the availability of pixellevel cloud-free observations when these data are combined. This study characterizes the coverage frequency of HLS V2.0 data for 2022, the first year all four satellites data are available. On average, the HLS data provide observations every 1.6 days at the global scale, and 2.2 days in the most data-scarce tropical regions. 0The frequency of cloud free land surface observations varies geographically and seasonally due to changes in satellite image swath overlap extent, cloud frequency, and solar illumination. The high latitudes (>~75°N) have the greatest number of clear observations from March to September, and the boreal regions have a lower number of clear observations in the summer months. 0The tropical regions have the lowest number of clear observations where the advantages of HLS are particularly evident compared to the use of Landsat or Sentinel-2 alone. Terrestrial monitoring can benefit from the more frequent HLS observations. We mapped the monthly and weekly number of clear observations globally to show where HLS data could support monthly or subweekly time series applications and where frequent cloud-free surface observations were still lacking.

ZHOU Qiang;  NEIGH Christopher;  JU Jungchang;  DABNEY Philip;  COOK Bruce;  ZHU Zhe;  CRAWFORD Christopher;  GASCON Ferran;  STROBL Peter;  SRIDHAR Madhu; 

2025-08-12

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

JRC140718

1558-0571 (online),   

https://ieeexplore.ieee.org/document/10852289,    https://publications.jrc.ec.europa.eu/repository/handle/JRC140718,   

10.1109/LGRS.2025.3533923 (online),