Effects of River Discharge, Wind Stress, and Slope Eddies on Circulation and the Satellite-Observed Structure of the Mississippi River Plume

Abstract

Abstract Satellite measurements of suspended sediment, temperature, and chlorophyll α are used in combination with surface current measurements to investigate surface circulation and structure of the Mississippi River plume. River discharge changes affect frontal locations, areal extent, and suspended sediment loads of the plume. During high river discharge (>20,000 m3 s−1) in spring, the sediment plume extends 23 km southwestward, covers 2700 km2, with maximum concentrations of 360 mg L−1. Plume temperatures vary seasonally from 10° to 28°C, with maximum surface fronts of 3.3°C km−1 in winter. East winds, prevalent in autumn, winter, and spring, drive a westward flow of river waters around the delta, linking two isolated shelf regions and increasing river discharge onto the Louisiana/Texas shelf. During peak river flow, this westward current exhibits velocities of 40–90 cm s−1, is 20 km wide, and transports 140,000–165,000 m3 s−1 of river and shelf water. It usually turns toward the coast between 89.5° W...