Challenges and Opportunities in Validating PACE/OCI, VIIRS, and EMIT for Coastal and Land Applications

With the advent of advanced spectrometers in the UV-VIS spectral range, a new generation of hyperspectral satellite missions are being developed, including PACE/OCI, EMIT, GLIMR, SBG, and GeoXO/OCX geared towards high spatial and spectral resolutions. These missions will fill in a critical gap for coastal water and land remote sensing beyond what the current VIIRS instrument can support. While VIIRS is excellent for global open ocean and land studies, it falls short for studies focusing on coastal waters, estuaries, lakes, wetlands, and crop fields requiring both high spatial and resolution. This study will investigate the needs for hyperspectral data in coastal water and land applications to address the gaps in the current observation datasets, using PACE/OCI, EMIT, and VIIRS datasets at selected sites such as the Florida Bay. The study reveals the challenges of using current data available due to spatial, spectral, and temporal resolution constraints, and potential mitigation strategies to address these challenges.

Preliminary comparisons between PACE/OCI and VIIRS shows that OCI products represent a major advance in remote sensing of water except that the spatial resolution of 1.2 km at nadir is a weakness for coastal applications. Technically OCI could provide high spatial resolution at 250m (cross-track only), but it's not a practical and standard product. Current studies show that 300m is a desired minimum spatial resolution for hyperspectral sensors that would meet the needs of coastal water applications (for example, https://oceancolor.gsfc.nasa.gov/about/projects/cyan/ ). VIIRS I-bands with a 375 m spatial resolution could potentially be used to generate some of the products, but are not able to address all the needs. However, the 7 VIIRS dual gain bands have unaggregated mode data downlinked and could enable a 250 m spatial resolution product crosstrack. The along-track spatial resolution still needs to be addressed. Meanwhile, the JPL EMIT (which has a spatial resolution of 60m, with a follow-on mission of 30m (SBG)) datasets can be used as a proxy for trade off studies between spatial and spectral resolution. This study will shed light on the paradigm shift from traditional broadband imaging to hyperspectral/high spatial remote sensing, as well as challenges and opportunities for a new generation of applications to be enabled operationally.