Optimizing EnMAP Satellite Operations: Acquisition Strategies and Data Access

Abstract

Since its launch on April 1, 2022, the EnMAP mission is delivering high-quality hyperspectral data to a growing global user base. The mission follows an open-access policy, providing freely available data for scientific use. Additionally, users are encouraged to submit observation proposals granting the opportunity to task EnMAP over specific areas of interest. This approach requires the mission operations to balance the needs of the users with the technical capabilities of the satellite. This contribution summarizes the status of the tasking strategy and data access in the EnMAP mission and the challenges that have been found and optimizations that have been introduced during the initial years of operation. Acquisition Strategy While many present satellite missions offer global mapping capabilities, this is not yet available for the current generation of imaging spectroscopy missions. Today's hyperspectral missions, like EnMAP, operate with a tasking mission concept, where acquisitions are prioritized and scheduled on specific locations. EnMAP follows a strategy that prioritizes observations entered by the users. To maximize the observation capacity, the remaining time is used for the so-called Background Mission which targets over 600 high-interest sites worldwide and, at the same time, aims to map large land surface areas. Experience from the first few years of operation shows that user requests are very unevenly distributed globally, which makes it a real challenge to fulfill all user requests. In addition, users order short acquisitions, i.e. single EnMAP products (30 x 30 km), underutilizing the potential observation capabilities of the satellite. Moreover, there is a growing number of requests for time series data which is difficult to achieve on the most requested geographic areas, due to the competing orders from different users. To address these difficulties, the so-called Foreground Mission was introduced. In this approach, a set of pre-selected areas over Europe are periodically observed and up-to-date information is shared at the EnMAP web site (www.enmap.org) about the status of the observations and future plans. The targets for the Foreground Mission were defined in collaboration with users representing different application areas. Following its positive reception by the user community, this initiative will be extended to other geographic areas in the future. In this contribution, we present the EnMAP acquisition approach and its optimization. We discuss the statistics of different observation modes and provide best practice recommendations for effectively tasking the EnMAP satellite to acquire data. Data access The open-access data policy of EnMAP allows users to access and download more than 110,000 products from the mission archive simply by registering as an EnMAP user. Archived products can be ordered and processed on-demand, with users selecting their preferred parameters, including product levels or the type of atmospheric correction. The available data product levels are: - Level 1B: radiometrically corrected data in sensor geometry - Level 1C: radiometrically and geometrically corrected, orthorectified data - Level 2A: atmospherically and geometrically corrected, orthorectified surface reflectance data with two atmospheric correction modes (land-mode and water-mode) The on-demand processing approach ensures that the EnMAP products adapt better to user needs and are generated using the up-to-date version of the processing software, which is regularly updated with enhancements. On the other hand, high-volume product requests can lead to long waiting times. To address the needs of users with no specific processing requirements or interested in large data volumes, EnMAP provides the complete set of Level 2A products processed with a standard set of parameters, available at the EOC-Geoservice and EOLab platforms. This dataset, verified as CEOS Analysis Ready Data (CEOS-ARD) for land applications, is optimized for large-scale use and easily accessible through the Geoservice STAC API, facilitating data discovery and access. In this contribution we will present what are the different deliverable EnMAP products, what are the available options to obtain them and the main differences that the users shall expect in each case.