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Characterizing the 2011 great flood plume of the Mississippi River
Ajit
Subramaniam, Lamont Doherty Earth Observatory, ajit@ldeo.columbia.edu
(Presenter)
The Mississippi River experienced record flooding in 2011. The average monthly flow measured at Tarbat Landing, MS in May 2011 was the largest since 1930. We characterized the Mississippi River plume during field surveys conducted on board the R/V Endeavor and R/V Cape Hatteras from 2nd to 28th July 2011 by making over 100 CTD casts. In addition, a full complement of optical measurements were made at 22 stations and the combination of satellite ocean color data along with the optical, physical, biological, and chemical data sets showed that the plume covered an area over 250,000 square kilometers, was as thin as 2m at some locations and contained extremely high amounts of colored dissolved organic matter and phytoplankton biomass. Unlike normal years when the plume flows mainly over the Louisiana Texas shelf, analysis of satellite imagery shows that in 2011, the plume spread southeastward covering about 150,000 km2 beyond the continental shelf on to the open waters of eastern Gulf of Mexico. The volume of discharge and nutrient loading in May have been identified as key parameters for predicting the size of the “Dead Zone” – the area of the bottom water with oxygen concentrations below 2 mg/L. Based on the values from May 2011, two separate statistical models predicted a record size for the Dead Zone for 2011. However, the actual measured area of the Dead Zone was smaller than predicted and we show that the actual direction of the Mississippi River plume is yet another important variable that might control the size of the Dead Zone, especially in years with high flow. We will present the results of our field survey. Presentation Type: Poster Session: Coupled Processes at Land-Atmosphere-Ocean Interfaces (Mon 4:00 PM) Associated Project(s):
Poster Location ID: 87
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