Observations of Diurnal Coastal-Trapped Waves with a Thermocline-Intensified Velocity Field

Tamara L. Schlosser, Nicole L. Jones, Ruth C. Musgrave, Cynthia E. Bluteau, Gregory N. Ivey, Andrew J. Lucas

Research output: Contribution to journalArticle

Abstract

Using 18 days of field observations, we investigate the diurnal (D1) frequency wave dynamics on the Tasmanian eastern continental shelf. At this latitude, the D1 frequency is subinertial and separable from the highly energetic near-inertial motion. We use a linear coastal-trapped wave (CTW) solution with the observed background current, stratification, and shelf bathymetry to determine the modal structure of the first three resonant CTWs. We associate the observed D1 velocity with a superimposed mode-zero and mode-one CTW, with mode one dominating mode zero. Both the observed and mode-one D1 velocity was intensified near the thermocline, with stronger velocities occurring when the thermocline stratification was stronger and/or the thermocline was deeper (up to the shelfbreak depth). The CTW modal structure and amplitude varied with the background stratification and alongshore current, with no spring-neap relationship evident for the observed 18 days. Within the surface and bottom Ekman layers on the shelf, the observed velocity phase changed in the cross-shelf and/or vertical directions, inconsistent with an alongshore propagating CTW. In the near-surface and near-bottom regions, the linear CTW solution also did not match the observed velocity, particularly within the bottom Ekman layer. Boundary layer processes were likely causing this observed inconsistency with linear CTW theory. As linear CTW solutions have an idealized representation of boundary dynamics, they should be cautiously applied on the shelf.

Original languageEnglish
Pages (from-to)1973-1994
Number of pages22
JournalJournal of Physical Oceanography
Volume49
Issue number7
DOIs
Publication statusPublished - Jul 2019

Cite this

Schlosser, Tamara L. ; Jones, Nicole L. ; Musgrave, Ruth C. ; Bluteau, Cynthia E. ; Ivey, Gregory N. ; Lucas, Andrew J. / Observations of Diurnal Coastal-Trapped Waves with a Thermocline-Intensified Velocity Field. In: Journal of Physical Oceanography. 2019 ; Vol. 49, No. 7. pp. 1973-1994.
@article{42e241f8478745b2a5c0b6b5102676e9,
title = "Observations of Diurnal Coastal-Trapped Waves with a Thermocline-Intensified Velocity Field",
abstract = "Using 18 days of field observations, we investigate the diurnal (D1) frequency wave dynamics on the Tasmanian eastern continental shelf. At this latitude, the D1 frequency is subinertial and separable from the highly energetic near-inertial motion. We use a linear coastal-trapped wave (CTW) solution with the observed background current, stratification, and shelf bathymetry to determine the modal structure of the first three resonant CTWs. We associate the observed D1 velocity with a superimposed mode-zero and mode-one CTW, with mode one dominating mode zero. Both the observed and mode-one D1 velocity was intensified near the thermocline, with stronger velocities occurring when the thermocline stratification was stronger and/or the thermocline was deeper (up to the shelfbreak depth). The CTW modal structure and amplitude varied with the background stratification and alongshore current, with no spring-neap relationship evident for the observed 18 days. Within the surface and bottom Ekman layers on the shelf, the observed velocity phase changed in the cross-shelf and/or vertical directions, inconsistent with an alongshore propagating CTW. In the near-surface and near-bottom regions, the linear CTW solution also did not match the observed velocity, particularly within the bottom Ekman layer. Boundary layer processes were likely causing this observed inconsistency with linear CTW theory. As linear CTW solutions have an idealized representation of boundary dynamics, they should be cautiously applied on the shelf.",
keywords = "Australia, Continental shelf, slope, Boundary currents, Dynamics, Waves, oceanic, INTERNAL TIDES, SHELF, CIRCULATION, GENERATION, TURBULENCE, ENERGY, OCEAN",
author = "Schlosser, {Tamara L.} and Jones, {Nicole L.} and Musgrave, {Ruth C.} and Bluteau, {Cynthia E.} and Ivey, {Gregory N.} and Lucas, {Andrew J.}",
year = "2019",
month = "7",
doi = "10.1175/JPO-D-18-0194.1",
language = "English",
volume = "49",
pages = "1973--1994",
journal = "Journal of Physical Oceanography",
issn = "0022-3670",
publisher = "American Meteorological Society",
number = "7",

}

Observations of Diurnal Coastal-Trapped Waves with a Thermocline-Intensified Velocity Field. / Schlosser, Tamara L.; Jones, Nicole L.; Musgrave, Ruth C.; Bluteau, Cynthia E.; Ivey, Gregory N.; Lucas, Andrew J.

In: Journal of Physical Oceanography, Vol. 49, No. 7, 07.2019, p. 1973-1994.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Observations of Diurnal Coastal-Trapped Waves with a Thermocline-Intensified Velocity Field

AU - Schlosser, Tamara L.

AU - Jones, Nicole L.

AU - Musgrave, Ruth C.

AU - Bluteau, Cynthia E.

AU - Ivey, Gregory N.

AU - Lucas, Andrew J.

PY - 2019/7

Y1 - 2019/7

N2 - Using 18 days of field observations, we investigate the diurnal (D1) frequency wave dynamics on the Tasmanian eastern continental shelf. At this latitude, the D1 frequency is subinertial and separable from the highly energetic near-inertial motion. We use a linear coastal-trapped wave (CTW) solution with the observed background current, stratification, and shelf bathymetry to determine the modal structure of the first three resonant CTWs. We associate the observed D1 velocity with a superimposed mode-zero and mode-one CTW, with mode one dominating mode zero. Both the observed and mode-one D1 velocity was intensified near the thermocline, with stronger velocities occurring when the thermocline stratification was stronger and/or the thermocline was deeper (up to the shelfbreak depth). The CTW modal structure and amplitude varied with the background stratification and alongshore current, with no spring-neap relationship evident for the observed 18 days. Within the surface and bottom Ekman layers on the shelf, the observed velocity phase changed in the cross-shelf and/or vertical directions, inconsistent with an alongshore propagating CTW. In the near-surface and near-bottom regions, the linear CTW solution also did not match the observed velocity, particularly within the bottom Ekman layer. Boundary layer processes were likely causing this observed inconsistency with linear CTW theory. As linear CTW solutions have an idealized representation of boundary dynamics, they should be cautiously applied on the shelf.

AB - Using 18 days of field observations, we investigate the diurnal (D1) frequency wave dynamics on the Tasmanian eastern continental shelf. At this latitude, the D1 frequency is subinertial and separable from the highly energetic near-inertial motion. We use a linear coastal-trapped wave (CTW) solution with the observed background current, stratification, and shelf bathymetry to determine the modal structure of the first three resonant CTWs. We associate the observed D1 velocity with a superimposed mode-zero and mode-one CTW, with mode one dominating mode zero. Both the observed and mode-one D1 velocity was intensified near the thermocline, with stronger velocities occurring when the thermocline stratification was stronger and/or the thermocline was deeper (up to the shelfbreak depth). The CTW modal structure and amplitude varied with the background stratification and alongshore current, with no spring-neap relationship evident for the observed 18 days. Within the surface and bottom Ekman layers on the shelf, the observed velocity phase changed in the cross-shelf and/or vertical directions, inconsistent with an alongshore propagating CTW. In the near-surface and near-bottom regions, the linear CTW solution also did not match the observed velocity, particularly within the bottom Ekman layer. Boundary layer processes were likely causing this observed inconsistency with linear CTW theory. As linear CTW solutions have an idealized representation of boundary dynamics, they should be cautiously applied on the shelf.

KW - Australia

KW - Continental shelf

KW - slope

KW - Boundary currents

KW - Dynamics

KW - Waves

KW - oceanic

KW - INTERNAL TIDES

KW - SHELF

KW - CIRCULATION

KW - GENERATION

KW - TURBULENCE

KW - ENERGY

KW - OCEAN

U2 - 10.1175/JPO-D-18-0194.1

DO - 10.1175/JPO-D-18-0194.1

M3 - Article

VL - 49

SP - 1973

EP - 1994

JO - Journal of Physical Oceanography

JF - Journal of Physical Oceanography

SN - 0022-3670

IS - 7

ER -