New insights into aquatic systems with hyperspectral data: The EnMAP satellite and it’s water-related ground segment processors

The EnMAP satellite and it's water related ground processor

The EnMAP user interface and user request scenarios

EnMAP (Environmental Mapping and Analysis Program) is a German hyperspectral satellite mission providing high quality hyperspectral image data on a timely and frequent basis. Main objective is to investigate a wide range of ecosystem parameters encompassing agriculture, forestry, soil and geological environments, coastal zones and inland waters. The EnMAP Ground Segment will be designed, implemented and operated by the German Aerospace Center (DLR). The Applied Remote Sensing Cluster (DFD) at DLR is responsible for the establishment of a user interface. This paper provides details on the concept, design and functionality of the EnMAP user interface and a first analysis about potential user scenarios. The user interface consists of two online portals. The EnMAP portal (www.enmap.org) provides general EnMAP mission information. It is the central entry point for all international users interested to learn about the EnMAP mission, its objectives, status, data products and processing chains. The EnMAP Data Access Portal (EDAP) is the entry point for any EnMAP data requests and comprises a set of service functions offered for every registered user. The scientific user is able to task the EnMAP HSI for Earth observations by providing tasking parameters, such as area, temporal aspects and allowed tilt angle. In the second part of that paper different user scenarios according to the previously explained tasking parameters are presented and discussed in terms of their feasibility for scientific projects. For that purpose, a prototype of the observation planning tool enabling visualization of different user request scenarios was developed. It can be shown, that the number of data takes in a certain period of time increases with the latitude of the observation area. Further, the observation area can differ with the tilt angle of the satellite. Such findings can be crucial for the planning of remote sensing based projects, especially for those investigating ecosystem gradients in the time domain

Sensitivity study for aquatic ecosystem monitoring with the DESIS hyperspectral sensor

The aquatic ecosystems of coastal and inland waters are more variable than the open ocean as water constituents and bottom substrates differ considerably in type, concentration and optical properties. Sensors with high spatial, spectral and radiometric resolution are therefore required to provide enough detail for mapping these highly complex environments. A new Earth observation instrument, designed for monitoring spectrally complex areas, is the DLR Earth Sensing Imaging Spectrometer (DESIS). This hyperspectral sensor, which covers a spectral range from 450 nm to 950 nm and has a spatial resolution of 30 meters, will be launched to the ISS in summer 2018. The goal of the present study is to specifically evaluate the performance of DESIS over aquatic ecosystems based on its sensor specifications. For this purpose, a sensitivity study was conducted in order to explore the spectral and radiometric properties of DESIS in the context of optically deep and shallow water mapping. The optical water properties and benthic cover types were chosen to represent typical inland and coastal waters. Forward simulations of hyperspectral measurements were made using the Water Color Simulator software WASI to study the expected DESIS radiances and their signal-to-noise ratios (SNR) for different atmospheric conditions. The impact of sensor noise on the retrieval of water constituents, benthos types and water depth was analyzed by applying inverse modelling to these reflectance spectra. The study assesses the mapping potential and limitations of a DESIS type sensor for these complex environments, which are usually much darker than land surfaces

The EnMAP Ground Segment user services and products

EnMAP (Environmental Mapping and Analysis Program) is a high-resolution imaging spectroscopy remote sensing mission dedicated to monitor and characterizing Earth's environment by providing accurate information on the state and evolution of terrestrial and aquatic ecosystems. EnMAP is equipped with a prism-based dual-spectrometer, which can make observations in the spectral range between 418.2 nm and 2445.5 nm with 224 bands and a high radiometric and spectral accuracy and stability. The EnMAP satellite was launched on 1 April 2022 and completed its commissioning phase in November 2022. From March 2023 EnMAP accepts user requests to acquire new acquisitions or download products from the mission archive. The EnMAP Ground Segment, under the responsibility of the German Aerospace Center (DLR), provides the services necessary to command the satellite and receive, archive and process the EnMAP data up to the three user product levels that can be ordered. These products are the radiometrically corrected at sensor top-of-the-atmosphere radiance product (L1B), the radiometrically corrected and orthorectified top-of-the-atmosphere radiance product (L1C) and the atmospherically corrected bottom-of-the-atmosphere reflectance product (L2A). The L2A processing supports options for Land processing, Water processing and a combine mode that automatically selects the correction based on pixel classification. In this contribution we offer an overview of the services provided by the EnMAP Ground Segment to the EnMAP data users: planning of new EnMAP acquisitions, access to archived data products and data processing. We cover in particular those aspects that, according to the user feedback, have been more challenging for the EnMAP users. We also provide an overview of the EnMAP products available and the different access or processing options that users can choose from

Vitalitätserfassung von Fichten mittels Fernerkundung

Die Vitalität vieler Baumarten ist durch den Klimawandel und die damit einhergehenden Wetteränderungen stark gefährdet. Der Bedarf an kostengünstigen Methoden zum großfl ächigen Monitoring von Waldfl ächen ist deshalb von großer Bedeutung. Im Projekt VitTree der Bayerischen Forstverwaltung wurde von einem Projektteam aus BOKU Wien, DLR, BaySF, ÖBf und LWF untersucht, in welchem Ausmaß und ab welchem Zeitpunkt Vitalitätsveränderungen von Bäumen mithilfe von Fernerkundungsdaten erfasst werden können. Das Ziel dieser neuen Methoden ist eine möglichst frühzeitige Erkennung von Veränderungen, idealerweise noch bevor diese für das menschliche Auge im Gelände erkennbar sin

The Ground Segment of the EnMAP Mission: from Tasking to Product Download

An overview of teh EnMAP Ground Segment services of interest for the users of the EnMAP data products

Laboratory for Essential Biodiversity Variables (EBV) Concepts – The “Data Pool Initiative for the Bohemian Forest Ecosystem”

Forest ecosystems respond very sensitively to climate and atmospheric changes. Feedback mechanisms can be measured via changes in albedo, energy balance and carbon storage. The Bavarian Forest National Park is a unique forest ecosystem with large non-intervention zones, which promote a large scale re-wilding process with low human interference. It provides important ecosystem services of clear water, carbon sequestration and recreation, and has fragile habitats with endangered forest species. The national park is therefore a very suitable field of research to study natural and near natural ecosystem processes. Under the leadership of the national park authority, experts from various European research institutions have joined forces to systematically establish a remote sensing data pool on the Bavarian Forest as a resource for their research. This collaborative effort provides an opportunity to combine various methodological approaches and data and to optimize products by sharing knowledge and expertise. The first objective of the data pool is to develop methods for the establishment of Essential Biodiversity Variables (EBV) based on a very sound and comprehensive data base. The recent advances in tighter collaboration of remote sensing and biodiversity science, especially with regard to the newly established EBV and RS-EBV concepts will help to improve the interdisciplinary research. However, such concepts and especially the underlying remote sensing data need to be developed, adapted and validated against biodiversity patterns. Such process needs an extensive set of in-situ and remotely sensed data in order to allow a thorough analysis. The Bavarian data pool fits these requirements through the commitment of all members and hence provides a variety of remote sensing data sets such as hyperspectral, Lidar as well as CIR and multispectral data, as well as a wealth of in-situ data of zoological and botanical transects. This combination allows setting sensor-specific, as well as species-specific analysis on different aspects, i.e. different processes between managed and natural forest, impact of climate change or species distribution mapping. The second objective is to develop concepts for EBV using Sentinel mission data combined with data from future contributing hyperspectral missions such as EnMAP. Spaceborne hyperspectral data has been identified by the remote sensing related biodiversity community as an important data source. However, the acquisition of airborne data is very expensive for regular coverage of forest stands and the entire forest ecosystem. This drawback will be overcome by the launch of the space-borne imaging spectroscopy mission EnMAP. It is a contributing mission to the Copernicus program and will be launched in 2018. EnMAP is expected to provide high quality imaging spectroscopy data on an operational basis and will be suitable for the retrieval of high resolution plant traits at local scales. First studies within the data pool have been focused on e.g. derivation of plant traits like chlorophyll, LAI and nitrogen and tree species classification with a special focus on rare species within the national park, just to name a few. Objective, purpose and content of the data pool will be shown as well as first selective developments

Water quality monitoring in Térraba Sièrpe Wetland (Costa Rica) using multi- and hyperspectral EO data

The project MONEOWET focuses on multispectral and hyperspectral Earth Observation (EO) data to investigate water quality in relation to agricultural activities within the Térraba Sièrpe Wetland in Costa Rica. This study corresponds to an initiative focused on investigating the applicability of remote sensing data in tropical systems. The main topic of this project is the use of EO data to assess the impacts and dynamics of agricultural activities on the sensitive RAMSAR wetland ecosystem Térraba Sièrpe at the mouth of the Térraba and Sièrpe rivers. One goal of this project is to develop a first EO database and define analytical methods for water quality studies in that area and beyond. The results will provide a deeper insight into the processes of the entire wetland ecosystem and may help to detect harmful damage to the fragile environment caused by surrounding agricultural activities. The long-term goal is sustainable water and land use management that is exemplary for many other tropical wetlands in Latin America. Scientists from Germany and Costa Rica are working together to collect data with established (e.g. Sentinel 2, Landsat 8) and new Earth Observation sensors (e.g. DESIS on the ISS) to assess water quality parameters and link these parameters to agricultural land use in the surrounding area. The common goal of the project is to evaluate the applicability of Landsat 8, Sentinel-2 and DESIS multi- and hyperspectral satellite imagery for water quality studies in tropical environments. Field campaigns were carried out during wet season (November 2018 and November 2019) and dry season (March 2019 and March 2021). The sampling sites for in-situ measurements were taken in the three main meanders of the Sièrpe River and the main meander of Térraba River within the wetland. At each sampling site, the spectral signature of the river was recorded using an Ocean Optics Sensor System (OOSS). The multispectral (Sentinel 2, Landsat 8) and hyperspectral EO (DESIS) data were atmospherically corrected to Bottom-of-atmosphere (BOA) reflectance using Sen2cor (ESA) and PACO (Python-based Atmospheric Correction, DLR), respectively. The WASI-2D inversion method, a semi-analytical model, which retrieves the optically active water quality variables: chlorophyll, total suspended matter (TSM) and colored dissolved organic matter (CDOM) was used and parameterized with site - specific inherent optical properties (SIOPs) of the area and applied to time series of L2A Sentinel, Landsat 8 and DESIS images. Some of the Sentinel-2 and Landsat overpasses were coincident with available field data, however DESIS images could not be obtained during field campaigns, thus only a qualitative evaluation is presented. Although cloud cover in the tropics is a major challenge, the influence of thin clouds could be corrected and the concentrations of TSM and CDOM could be derived quantitatively. Chlorophyll could not be derived reliably in most areas, in particular not from Landsat 8, most likely because its concentration was relatively low and water absorption was dominated by CDOM. The high temporal dynamics of the river system, which is strongly influenced by tides, makes comparison of satellite data collected at different times very difficult, as is comparison with field data. Nevertheless, Sentinel 2-derived maps of water constituents and corresponding Landsat 8 and DESIS images show good agreements in the average concentrations of TSM and CDOM concentration and plausible spatial patterns, and field measurements show that they are in a plausible range. The results indicate that under favorable observational and environmental conditions, the applied atmospheric correction and the used retrieval algorithm are suitable to use DESIS, Sentinel 2 and Landsat 8 data for mapping TSM and CDOM in tropical environments, while chlorophyll is challenging. Their quantitative determination by satellite is therefore an important contribution of this project to the ecological assessment of the waters and the surrounding environment of the study area

Feasibility Study for an Aquatic Ecosystem Earth Observing System Version 1.2.

International audienceMany Earth observing sensors have been designed, built and launched with primary objectives of either terrestrial or ocean remote sensing applications. Often the data from these sensors are also used for freshwater, estuarine and coastal water quality observations, bathymetry and benthic mapping. However, such land and ocean specific sensors are not designed for these complex aquatic environments and consequently are not likely to perform as well as a dedicated sensor would. As a CEOS action, CSIRO and DLR have taken the lead on a feasibility assessment to determine the benefits and technological difficulties of designing an Earth observing satellite mission focused on the biogeochemistry of inland, estuarine, deltaic and near coastal waters as well as mapping macrophytes, macro-algae, sea grasses and coral reefs. These environments need higher spatial resolution than current and planned ocean colour sensors offer and need higher spectral resolution than current and planned land Earth observing sensors offer (with the exception of several R&D type imaging spectrometry satellite missions). The results indicate that a dedicated sensor of (non-oceanic) aquatic ecosystems could be a multispectral sensor with ~26 bands in the 380-780 nm wavelength range for retrieving the aquatic ecosystem variables as well as another 15 spectral bands between 360-380 nm and 780-1400 nm for removing atmospheric and air-water interface effects. These requirements are very close to defining an imaging spectrometer with spectral bands between 360 and 1000 nm (suitable for Si based detectors), possibly augmented by a SWIR imaging spectrometer. In that case the spectral bands would ideally have 5 nm spacing and Full Width Half Maximum (FWHM), although it may be necessary to go to 8 nm wide spectral bands (between 380 to 780nm where the fine spectral features occur -mainly due to photosynthetic or accessory pigments) to obtain enough signal to noise. The spatial resolution of such a global mapping mission would be between ~17 and ~33 m enabling imaging of the vast majority of water bodies (lakes, reservoirs, lagoons, estuaries etc.) larger than 0.2 ha and ~25% of river reaches globally (at ~17 m resolution) whilst maintaining sufficient radiometric resolution

User Inquiries and Ground Segment Operation Activities

Since the beginning of the operational phase in November 2022, the Environmental Mapping and Analysis Programm (EnMAP) has gathered substantial interest within the Earth Observation community, counting a considerable number of more than 1800 registered users from over 80 different countries across the globe. The EnMAP data archive is also used very frequently by users with ordering and downloading approx. 2000 tiles per months. Any science user can submit its (his/her) own observations request via the EnMAP Instrument Planning Portal (IPP, https://planning.enmap.org/, also reachable through the official website www.enmap.org), by submitting a proposal. The IP portal also provides access links to the entire EnMAP data archive via the EOWEB Geoportal. The number of users requesting future observations varies significantly based on geographic location. Notably, Europe sees the highest demand for the EnMAP mission, leading to challenges such as conflicting orders for areas within the same orbit. This convergence has introduced complexities in data acquisition, particularly for time series and orchestration of field campaigns. To ensure (increase) regular data acquisition and boost mission efficiency, a "Foreground Mission" has been introduced. This entails prioritized acquisition of extended 990-kilometer flightlines (stripes) over Europe, with a specific focus on Germany. This strategic approach aims to improve data coverage in Germany and streamlines recurring acquisitions along key transects. First this informative presentation provides an assessment of ground segment operations, with special attention given to user feedback and inquiries. Along the way, it outlines the most prevalent user concerns and highlights the strategic factors involved in requesting observations. As second part the audience gains deeper insight into the newly implemented Foreground Mission initiative