Shedding Light on the Ocean Remote Sensing Blind Spot - Spanning the Submesoscale Observational Gap with Drones

Abstract:

For 40 years remote sensing has played a key role in our understanding of ocean biology, revealing the incredibly patchy spatial structure of near-surface plankton across scales. From the Nimbus 7’s noteworthy Coastal Zone Color Scanner to the recent use of CALIPSO’s LiDAR to monitor diel migration across the ocean, significant advancements in our understanding of ocean biology have accelerated with increased observational capabilities. At present, it is increasingly clear that small unoccupied aircraft systems (sUAS) and associated science-grade sensors are no longer just prototypes, but rather mature enough to join the suite of instruments advancing our ability to observe the spatiotemporal complexity of ocean biology. The ocean sub-mesoscale represents a remote sensing blindspot, a major gap in scales of space and time that cannot be observed practically by ship-based tools and satellite platforms. Indeed, sUAS are now a potentially transformative tool in the study of submesoscale and finer dynamics because of their ability to bridge these gaps. In addition to increased spatial resolution over satellites and occupied aircraft, the ability to observe fine scale ocean features many times within a single day can revolutionize our understanding of temporal variation and diel patterns in ocean biology and ecology. This high immediacy, coupled with modular sensors (e.g. hyperspectral, thermal) can resolve variability in features where flow can be rapid, water constituents optically complex, and biological response highly variable. These low cost, high endurance, reliable platforms and science-grade sensors can increasingly be leveraged as primary scientific tools in fine-scale oceanographic research and as complements to more complex and intensive large-scale oceanographic campaigns. Just as profiling Argo floats have lifted the veil on ocean temperature and salinity at depth across the globe, and ocean gliders have provided sustained observations of 3D structure and biogeochemistry across mesoscales, sUAS can now provide ocean color, surface biogeochemistry, and sea surface temperature data at finer spatial scales and temporal cadences and will reveal entirely new processes and biophysical dynamics.