On the processes that influence the transport and fate of Mississippi waters under flooding outflow conditions

Yannis S. Androulidakis, Vassiliki H Kourafalou

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

The Mississippi River (MR) freshwater outflow is a major circulation forcing mechanism for the Northern Gulf of Mexico. We investigate the transport and fate of the brackish waters under flood conditions. The largest outflow in history (45,000 m3/s in 2011) is compared with the second largest outflow in the last 8 years (41,000 m3/s in 2008). Realistically forced simulations reveal the synergistic effect of enhanced discharge, winds, stratification of ambient shelf waters, and offshore circulation over the transport of plume waters. The strongest impact is attributed to the evolution of the Loop Current (LC) and associated frontal cyclonic eddies and anticyclonic rings, which exhibited distinctly different influence during the two study periods. The northward LC intrusion in the summer of 2011 weakened and blocked the buoyancy-driven downstream (westward) transport of brackish waters. The 2011 flood was thus characterized by upstream (eastward) flow and an extensive coverage of the Mississippi-Alabama-Florida shelf. An immediate response between the LC and the brackish offshore eastward spreading is computed during and after this historic event. The absence of a LC northward intrusion during the 2008 flood, in combination with wind effects, promotes downstream advection of MR waters towards the Louisiana-Texas shelf; large amounts of buoyant waters are also retained near the Delta, subject to local offshore advection under the synergistic action of LC-associated counter-rotating eddies.

Original languageEnglish (US)
Pages (from-to)143-164
Number of pages22
JournalOcean Dynamics
Volume63
Issue number2-3
DOIs
StatePublished - Mar 2013

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Keywords

  • Buoyant plume
  • HYCOM
  • Mississippi River
  • Northern Gulf of Mexico
  • Numerical modeling
  • River flood

ASJC Scopus subject areas

  • Oceanography

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