# Biological and physical impacts of ageostrophic frontal circulation driven by confluent front with vertical mixing

Author(s) Nagai, Takeyoshi, Tandon, Amit, Gruber, Nicolas, McWilliams, James C.
Publication Type Journal Items, Publication Status: Published
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## Detailed Information

Title Biological and physical impacts of ageostrophic frontal circulation driven by confluent front with vertical mixing
Author(s) Nagai, Takeyoshi
Tandon, Amit
Gruber, Nicolas
McWilliams, James C.
Journal or Series Title Dynamics of atmospheres and oceans
Volume Number 45
Issue Number 3-4
Start Page 229
End Page 251
ISSN 0377-0265
Publisher Elsevier
Publication Place Amsterdam
Publication Date 2008-00-00
Keyword(s) Front
Vertical mixing
Ageostrophic secondary circulations
Water mass subduction
Primary production
Nutrient upwelling
Abstract Subduction, upwelling, and phytoplankton blooms are commonly observed features at oceanic fronts. This study isolates the role of vertical mixing for enhanced production and water mass subduction near fronts, considering the time-developing problem with a Semi-Geostrophic circulation model coupled to a planktonic ecosystem model. Our model results show that vertical mixing in the surface boundary layer strongly modifies the time evolution of the front and of its associated biology. Ageostrophic flows caused by the combined effects of confluence and vertical mixing enhance primary production on the less dense side and increase water mass subduction on the dense side of the front. Confluence alone results in the intensification of the front by the same advective response, while the phytoplankton bloom on the less dense side does not arise without vertical mixing. Vertical mixing alone slumps the front near the surface and provides weak subduction on the dense side and uplift of the isopycnals at the center of the front. We find that it is possible to sustain an isolated phytoplankton patch above the domed isopycnals at the center of the front with the nutrients supplied by the secondary circulations arising due to vertical mixing. These results suggest that the phytoplankton bloom and patches found on the less dense side of fronts in many field observations are likely caused by fine-scale along-isopycnal upwelling of nutrients forced by adiabatic confluence in the meander trough of fronts and further pumping and entrainment of nutrients by the secondary circulation due to vertical mixing. Isolated patches observed at the center of the front in many frontal surveys could be caused by secondary flows due to vertical mixing.
DOI 10.1016/j.dynatmoce.2007.12.001
Additional Notes Available online 5 July 2008
Document Type Article
Publication Status Published
Language English
Assigned Organisational Unit(s) 03731
Organisational Unit(s)
NEBIS System Number 000000464
Source Database ID PP-43403
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@article{Ng2008,
author = "Nagai, Takeyoshi and Tandon, Amit and Gruber, Nicolas and McWilliams, James C.",
title = "{B}iological and physical impacts of ageostrophic frontal circulation driven by confluent front with vertical mixing",
journal = "Dynamics of atmospheres and oceans",
year = 2008,
volume = "45",
number = "3-4",
pages = "229--251",
}


E-Citations record created: Fri, 02 Apr 2010, 00:13:57 CET