Ocean Color Indices of Frontal Boundary Movements: A Multi-Sensor View

Strong and optically conspicuous frontal boundaries are common in the river-dominated Louisiana-Texas Shelf (LTS). Variable wind stress forcing along cross-shelf density gradients results in convergences/divergences that may lead to rapid vertical water mass displacements. In cases where near-bottom shelf waters are displaced to the surface, the associated optical anomaly is often distinct in satellite ocean color data. A satellite-observed optical feature consistent with near-bottom-water ventilation is examined over the LTS with multiple satellite-based ocean color radiometers (OLCI, VIIRS), as well as data from the Advanced Baseline Imager (ABI) on the geostationary GOES-R platform. In the aftermath of an atmospheric cold front passage and sustained northerly winds, the combined satellite analysis reveals a rapidly westward moving optical front delineated by a sharp visible-band reflectivity gradient. Ocean model simulations reproduce a qualitatively similar displacement of surface density fields that is consistent with advection by the along-front current with a potentially modulating influence from the diurnal heating. This study serves as an example of the kind of analyses that may be possible from future geostationary ocean color missions.