Spiral inertial waves emitted from geophysical vortices

Peng Wang, Tamay M Ozgokmen

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

By numerically simulating an initially unstable geophysical vortex, we discover for the first time a special kind of inertial waves, which are emitted in a spiral manner from the vortices; we refer to these waves as spiral inertial waves (SIWs). SIWs appear at small Rossby numbers (0.01 ≤ Ro ≤ 1) according to our parameter sweep experiments; the amplitude, wavelength and frequency of SIWs are sensitive to Rossby numbers. We extend the Lighthill-Ford radiation into inertial waves, and propose an indicator for the emission of inertial waves; this indicator may be adopted into general circulation models to parameterize inertial waves. Additionally, in our tracer releasing experiments, SIWs organize tracers into spirals, and modify the tracer's local rate of change by advecting tracers vertically. Further, the spirals of SIWs resembles some spiral features observed in the ocean and atmosphere, such as spiral ocean eddies and spiral hurricane rainbands; thus, SIWs may offer another mechanism to form spiral eddies and rainbands. Since no density anomaly is required to generate the spirals of SIWs, we infer that the density anomaly, hence the baroclinic or frontal instability, is unlikely to be the key factor in the formation of these spiral features.

Original languageEnglish (US)
Pages (from-to)22-42
Number of pages21
JournalOcean Modelling
Volume99
DOIs
StatePublished - Mar 1 2016

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vortex
Vortex flow
tracer
rainband
Rossby number
eddy
anomaly
Hurricanes
ocean
hurricane
general circulation model
experiment
Experiments
wavelength
Radiation
Wavelength
atmosphere

Keywords

  • Lighthill-Ford radiation
  • Spiral eddy
  • Spiral rainband
  • Vortex Rossby wave

ASJC Scopus subject areas

  • Atmospheric Science
  • Oceanography
  • Geotechnical Engineering and Engineering Geology
  • Computer Science (miscellaneous)

Cite this

Spiral inertial waves emitted from geophysical vortices. / Wang, Peng; Ozgokmen, Tamay M.

In: Ocean Modelling, Vol. 99, 01.03.2016, p. 22-42.

Research output: Contribution to journalArticle

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AB - By numerically simulating an initially unstable geophysical vortex, we discover for the first time a special kind of inertial waves, which are emitted in a spiral manner from the vortices; we refer to these waves as spiral inertial waves (SIWs). SIWs appear at small Rossby numbers (0.01 ≤ Ro ≤ 1) according to our parameter sweep experiments; the amplitude, wavelength and frequency of SIWs are sensitive to Rossby numbers. We extend the Lighthill-Ford radiation into inertial waves, and propose an indicator for the emission of inertial waves; this indicator may be adopted into general circulation models to parameterize inertial waves. Additionally, in our tracer releasing experiments, SIWs organize tracers into spirals, and modify the tracer's local rate of change by advecting tracers vertically. Further, the spirals of SIWs resembles some spiral features observed in the ocean and atmosphere, such as spiral ocean eddies and spiral hurricane rainbands; thus, SIWs may offer another mechanism to form spiral eddies and rainbands. Since no density anomaly is required to generate the spirals of SIWs, we infer that the density anomaly, hence the baroclinic or frontal instability, is unlikely to be the key factor in the formation of these spiral features.

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