Turbulent Mixing in a Far-Field Plume During the Transition to Upwelling Conditions: Microstructure Observations From an AUV

TY - JOUR

T1 - Turbulent Mixing in a Far-Field Plume During the Transition to Upwelling Conditions

T2 - Microstructure Observations From an AUV

AU - Fisher, Alexander W.

AU - Nidzieko, Nicholas J.

AU - Scully, Malcolm E.

AU - Chant, Robert J.

AU - Hunter, Elias J.

AU - Mazzini, Piero L.F.

N1 - Funding Information: The authors are indebted to Dave Loewensteiner for field assistance and AUV preparation. We also thank Ken Roma, captain of the R/V Arabella, for assistance in deployment and recovery of the AUV, and two anonymous reviewers, whose constructive comments improved the manuscript. Data are available in ASCII format in the supporting information. This work was supported by NSF awards OCE-1334398, OCE-1745258, and OCE-1334231. Publisher Copyright: ©2018. American Geophysical Union. All Rights Reserved.

PY - 2018/9/28

Y1 - 2018/9/28

N2 - A REMUS 600 autonomous underwater vehicle was used to measure turbulent mixing within the far-field Chesapeake Bay plume during the transition to upwelling. Prior to the onset of upwelling, the plume was mixed by a combination of energetic downwelling winds and bottom-generated shear resulting in a two-layer plume structure. Estimates of turbulent dissipation and buoyancy flux from a nose-mounted microstructure system indicate that scalar exchange within the plume was patchy and transient, with direct wind mixing constrained to the near surface by stratification within the plume. Changing wind and tide conditions contributed to temporal variability. Following the separation of the upper plume from the coast, alongshore shear became a significant driver of mixing on the shoreward edge of the plume.

AB - A REMUS 600 autonomous underwater vehicle was used to measure turbulent mixing within the far-field Chesapeake Bay plume during the transition to upwelling. Prior to the onset of upwelling, the plume was mixed by a combination of energetic downwelling winds and bottom-generated shear resulting in a two-layer plume structure. Estimates of turbulent dissipation and buoyancy flux from a nose-mounted microstructure system indicate that scalar exchange within the plume was patchy and transient, with direct wind mixing constrained to the near surface by stratification within the plume. Changing wind and tide conditions contributed to temporal variability. Following the separation of the upper plume from the coast, alongshore shear became a significant driver of mixing on the shoreward edge of the plume.

KW - autonomous underwater vehicle

KW - mixing

KW - river plume

KW - turbulence

KW - upwelling

UR - http://www.scopus.com/inward/record.url?scp=85053735041&partnerID=8YFLogxK

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U2 - https://doi.org/10.1029/2018GL078543

DO - https://doi.org/10.1029/2018GL078543

M3 - Article

SN - 0094-8276

VL - 45

SP - 9765

EP - 9773

JO - Geophysical Research Letters

JF - Geophysical Research Letters

IS - 18

ER -