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In the context of Long Term Data Preservation, ESA, with the support of the Instrument Data Evaluation and Quality Analysis Service (IDEAS+) team, reprocessed over 600’000 Landsat 1-5 Multi-Spectral Scanner (MSS) products acquired in the period 1975 - 2001 from the European Ground Stations complementing the existing 1 million Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) Level 1 products, with a geographical coverage from Greenland to Continental Europe and North Africa. The reprocessing software and quality control tool developed for the reprocessing present new features aimed at improving the radiometric and geometric accuracy, image data recovery and including additional quality assurance information. An accurate geometric and radiometric accuracy evaluation across the over 40-years long operative life of Landsat is vital for the exploitation of long time series analysis and for the future development of multi-mission Analysis Ready Data (ARD). This paper proposes to evaluate the geometric accuracy and the radiometric calibration accuracy of the Landsat Level 1 products delivered by ESA. It is obvious that across Landsat historical mission the accuracy is not the same; data are acquired with the MSS, the TM and the ETM+ sensors with improved characteristics for the most recent ones. All these differences between remote sensing systems, did not preclude to engineer processing algorithms with one main objective to harmonize physical measurement and ensure interoperability with the ongoing missions such as Landsat 8 - OLI / Sentinel 2 – MSI. This approach is a key aspect for the future development of multi mission ARD. The geometric quality assurance parameters are exposed in the Level 1 products. These scene based parameters allows to filter out and select, for a given region, if needed the most accurate products. Also, to demonstrate that these parameters are consistent is fundamental. Because of the ageing of missions, specifically for MSS missions, the processing cannot solely rely on information coming from telemetry. It is mandatory to apply ground model and to estimate both external and internal orientation parameters for what concerned the geometric model. Furthermore, for some parameters, the use of single scene for calibration of geo referencing model is not sufficient and the estimate of parameters becomes more robust when considering, instead of one scene, all data recorded in the acquisition period and downlinked to the receiving station. Also, the proposed methodology herein validates the stability of geometric accuracy for a long period of time within the orbit. The product quality assurance parameters are compared with the same ones but inferred from an image matching methods comparing disparity between two geometric grids; the input ESA image and geometric reference image (Global Land Survey data). A comparison with relative USGS products is also performed.
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