Structure of submesoscale fronts of the mississippi river plume

Tao Wang*, Roy Barkan, James C. Mcwilliams, M. Jeroen Molemaker

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Submesoscale currents (SMCs), in the forms of fronts, filaments, and vortices, are studied using a highresolution (~150m) Regional Oceanic Modeling System (ROMS) simulation in the Mississippi River plume system. Fronts and filaments are identified by large horizontal velocity and buoyancy gradients, surface convergence, and cyclonic vertical vorticitywith along-coast fronts and along-plume-edge filaments notably evident. Frontogenesis and arrest/destruction are two fundamental phases in the life cycle of fronts and filaments. In the Mississippi River plume region, the horizontal advective tendency induced by confluence and convergence plays a primary role in frontogenesis. Confluent currents sharpen preexisting horizontal buoyancy gradients and initiate frontogenesis. Once the fronts and filaments are formed and the Rossby number reaches O(1), they further evolve frontogenetically mainly by convergent secondary circulations, which can be maintained by different cross-frontmomentumbalance regimes.Confluentmotions and preexisting horizontal buoyancy gradients depend on the interaction between wind-induced Ekman transport and the spreading plume water. Consequently, the direction of wind has a significant effect on the temporal variability of SMCs, with more active SMCs generated during a coastally downwellingfavorable wind and fewer SMCs during an upwelling-favorable wind. Submesoscale instabilities (~1-3 km) play a primary role in the arrest and fragmentation of most fronts and filaments. These instabilities propagate along the fronts and filaments, and their energy conversion is a mixed barotropic-baroclinic type with horizontal-shear instabilities dominating.

Original languageEnglish
Pages (from-to)1113-1131
Number of pages19
JournalJournal of Physical Oceanography
Volume51
Issue number4
DOIs
StatePublished - 2021

Keywords

  • Ageostrophic circulations
  • Baroclinic flows
  • Frontogenesis/frontolysis
  • Fronts
  • Instability

Fingerprint

Dive into the research topics of 'Structure of submesoscale fronts of the mississippi river plume'. Together they form a unique fingerprint.

Cite this