Applications of a Harmonized Landsat, Sentinel-2, and PlanetScope (HLSP) Surface Reflectance Product

The expansion of satellite-based sensor constellations offer game-changing opportunities for observation-driven monitoring with unprecedented temporal resolution and timeliness. However, distributed sensor observations are not typically directly interoperable, and require significant preparation to add value and enable actionable and impactful insights.

The Harmonized Landsat, Sentinel-2, and PlanetScope (HLSP) surface reflectance (SR) product adopts an innovative data fusion methodology and brings enhancements in temporal resolution, quality, and interoperability to help unlock the full potential of time-series remote sensing data from both public and commercial sources.

HLSP leverages the comprehensive harmonization methodology developed as part of Planet’s flagship high resolution (3 m) analysis ready data products, which adopt an implementation of the CubeSat-Enabled Spatio-Temporal Enhancement Method (CESTEM) to leverage near-daily PlanetScope observations in synergy with public mission sources. HLSP is produced with a 30 m pixel size and consists of a traceable mixture of 30 m downsampled PlanetScope, Sentinel-2, and Landsat 8/9 clear-sky observations that have been directly fused and harmonized into a seamless sensor-agnostic data stream consistent with FORCE (The Framework for Operational Radiometric Correction for Environmental Monitoring) SR data.

HLSP moves towards fully unlocking the value of the multi-year (~2017 to present) near-daily PlanetScope archive, complemented and enhanced by Sentinel-2 and Landsat observations. As a near-daily, multi-year, analysis-ready product, HLSP provides the foundational characteristics required for use cases across many industries via high quality AI-driven insights and analytics. This presentation will showcase the impacts of HLSP processing on multi-constellation sensor interoperability, cross-sensor radiometric consistency, and temporal resolution, and highlight relevant use cases. Highlighted use cases include application of time-series HLSP data for daily phenological monitoring, land cover change and deforestation detection and mapping, and multi-modal (optical and passive/active microwave) data fusion.

The preliminary results support HLSP as a core demonstration of how public missions can be used to complement private Earth Observation efforts to produce analysis-ready SR datasets with significantly enhanced quality, temporal resolution, interoperability, and usability. The HLSP SR product is envisioned as a foundational analysis ready data building block to support effective and accurate monitoring and mitigation of impacts from critical environmental challenges.