Sentinel-2 and Landsat missions are the primary source of moderate-resolution, optical images for aquatic science and applications within the next decade. The remarkable data quality and quantity offered by this virtual constellation have made possible new scientific avenues and operational applications, such as early warning systems for harmful algal bloom detection.

In this presentation, I will present our to-date experiences on how Sentinel-2A/B and Landsat-8 products compare over bodies of water at three different product levels, i.e., L1B/C, L2, and L3. We will discuss different aspects of data product harmonization and how such an existing constellation can provide temporal gap filling for future hyperspectral data. Assuming high-fidelity spectroscopic observations enabling more accurate/precise products, It is possible to harness higher-level products (made possible through spectrometry) to enhance products derived from multispectral observations.

The NASA Hyperion spectrometer carried onboard the Earth Observing One (EO-1) satellite pioneered orbital civilian observations for visible through short-wave infrared wavelengths acquired at moderate spatial resolution (30 m) to match the Landsat spatial scale, and at relatively high spectral resolution (10 nm). The EO-1/Hyperion acquired more than 90,000 images globally over almost 17 years of service (2000-2017). These data sets have successfully been used for a variety of science and application studies. We will provide examples of studies using Hyperion data to retrieve carbon cycle biophysical parameters such as photosynthetic Light Use Efficiency (LUE), Net and/or Gross Primary Production (NPP, GPP), and the Absorbed Photosynthetically Active Radiation (APAR) of incident sunlight, partitioned into the APAR fractions for green (APARchl) and non-green (APARnon-chl) canopy sectors. Several of these studies are based on time series analyses utilizing eddy covariance flux tower data, and retrieval approaches include statistical methods (e.g., Partial Least Squares Regression), forward modeling, and direct use of a fuller suite of spectral indices. A subset drew upon NASA’s MODerate Imaging Spectroradiometer (MODIS) data to develop spectral information for convolving the Hyperion bands for input into existing models and for validations. This presentation will address several workshop objectives, including aspects of data harmonization, validation strategies, and recommended products for orbital spectroscopy and hyperspectral instruments.

The NRC 2017 Earth Decadal Survey recommended a new NASA “Designated” program element, the Surface Biology and Geology (SBG) Targeted Observable. The specific SBG targeted observables – surface biology & geology, functional traits of terrestrial vegetation and inland & near-coastal aquatic ecosystems, active geologic processes, ground & water temperature, gross primary production (GPP), and snow spectral albedo were identified. In response to the 2017 NRC Decadal Survey, NASA’s Earth Science Directorate developed a multi-center SBG Designated Observable Study Plan for science, applications, systems engineering and costing studies to prepare for an October 2021 Key Decision Point. The SBG is the first Decadal Survey designated “mission” that implements NASA Earth Science Division’s: Directive On Project Applications Program. This directive guides the implementation of a Project Applications Program within the Earth Science Division. As a result, an Application Working Group (APPWG) was established with two major objectives: 1. Identify key applications requirements, latency, revisit, and specific products for use in both the applications community and the SBG architectures study team, 2. Inform and identify the applied science community and its stakeholders through workshops, thematic working groups, and scheduled telecons. The APPWG builds on NASA’s applied science program which includes projects in agriculture, water resources, aquatic & terrestrial ecosystems, volcanology, disasters, public health, and climatology along with partnerships in federal, state, and local governments, and various non-governmental organizations.

In the framework of the Copernicus Programme, the user consultation process highlighted strong requirements in relation to both stability and continuity of products and services provision. Several of these requirements will be matched by the Next Generation (NG) of Sentinel missions (1 to 6 series) ensuring the continuity of initial observations and by the so called High Priority Candidate Missions including the hyperspectral mission.
The ongoing project “RFP/ Chime Mission Requirements Consolidation” funded by ESA, aims at assessing if the development of a hyperspectral satellite mission provides potential value-added products to current Sentinel missions in the "Agriculture & food security” and “Raw materials exploration" application domains. The user information needs within these two application domains, are associated to geophysical variables and the related EO derived products. The project based on already available data and algorithms, use them to simulate hyperspectral sensor configuration (spectral, spatial and temporal resolution) and test the resulting outputs in comparison and in synergy with the corresponding product from multispectral missions (e.g. Sentinel 2) in terms of added value.
From the consolidation analysis, the project has identified about ten products useful to map topsoil properties (soil organic carbon content, Soil texture), vegetation properties (LAI, canopy water content, Leaf and canopy pigment content, Leaf Mass/Area) and to characterize raw material compositions. These products have been generated using state-of-the-art retrieval algorithms and exploiting the available airborne hyperspectral data from AVIRIS-NG and APEX sensors, acquired in 2018 over a test site in the area of Grosseto (Italy) and Cuprite (USA).

The European Forest Fire Information System (EFFIS) allows to visualize active fire/ hot spot data and products derived by both Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) sensors.
Numerous are the advantages provided by the system on active fires as the data are updated 6 times daily and the MODIS and VIIRS sensors have TIR bands ideally positioned to detect thermal anomalies.
However, due of the coarse resolution of the two sensors, small in size or low in intensity fires are missed from the global product system.
In this context, Copernicus Sentinel sensors and hyperspectral space sensors such as PRISMA and EnMap with better spatial resolution (10-30m/px) can contribute to map smaller fires. This work addresses wildfires detection from space by using hyperspectral features of biomass burning in the VIS-NIR-SWIR resulting from ASI -AGI project. The study aims to deliver fire detection indexes customized on PRISMA bands which can better respond to Potassium emission and CO2 absorption features.
In addition, results from Free Research - Fondo integrativo speciale per la ricerca- FIRS 2016 project are reported focusing on exploring the Sentinel 2 data potential to characterize wildfires and High Temperature Events in central Italy are reported to show Copernicus Sentinel 2-Landsat 8 programs contribution for detecting wildfires in central Italy.

NASA is evaluating satellite mission architectures to observe Earth’s surface biology and geology (SBG) from space. The mission will likely include at least one imaging spectrometer spanning the visible and shortwave infrared (VSWIR) wavelength region and multi- or hyperspectral imager in the thermal infrared (TIR). These sensors could potentially support science and application objectives of the aquatic remotes sensing community, including evaluation of coastal and inland aquatic habitats including composition; ecological condition; and areal distribution, extent and change. Such observations could also improve our understanding of biogeochemical cycling in watersheds and coastal and limnological geological composition and dynamic processes. They could also help monitor response to disasters, hazards such as harmful algal blooms, and water quality and availability. However, how much of these objectives can be realized depends on the mission characteristics. These include the observational geometry, which can be designed to reduce glint, optimize optic path lengths through the atmosphere and maximize solar illumination; the orbital configuration and number of instruments and platforms to increase sampling frequency; and instruments with high-performance radiometric, spectral and spatial characteristics supported by a robust, mission-long characterization and calibration program. This presentation will offer a discussion on the limitations of candidate SBG architecture and sensor characteristics in supporting aquatic remote sensing objectives and whether strategic cooperation with other satellite missions and other resources could overcome them.