Response of Louisiana Coastal Environments to a Cold Front Passage

Abstract

The effect of a cold front passage on suspended sediment concentrations, water temperatures, and coastal circulation off Louisiana is examined via remote sensing with the Multispectral Atmospheric Mapping Sensor (MAMS). This 12 channel visible- infrared scanning spectrometer is flown on NASA's ER- 2 aircraft, collecting 100 m resolution data over a 37 km swath from an altitude of 20 km. Time series charts of water temperature and suspended sediment content record the rapid (days) response of these shallow coastal waters to the cold front system of March 30 - April 1, 1989. The river discharge sediment plumes stream down wind from the coast, remaining as coherent discrete water masses for up to 100 km. Detectable temperature gradients evolve rapidly in the estuarine waters in response to changing atmospheric conditions, with lowest temperatures developing in shallowest regions. Water level setup and setdown created by surface winds and barometric pressure strongly affect the exchange of river, estuarine and Gulf water. Behavior of the turbid river and estuarine discharge plumes is important as they serve as the source for new sediment deposits along the coastline. The utility of time series from high resolution, multispectral imagery in coastal environmental research, resource management, and pollution control is clear from this short term, multimission coverage.