Evaluation and sensitivity analysis of an ocean model response to Hurricane Ivan

Jr R. Halliwell, Lynn K Shay, J. K. Brewster, W. J. Teague

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

An ocean model response to Hurricane Ivan (2004) over the northwest Caribbean Sea and Gulf of Mexico is evaluated to guide strategies for improving performance during strong forcing events in a region with energetic ocean features with the ultimate goal of improving coupled tropical cyclone forecasts. Based on prior experience, a control experiment is performed using quasi-optimal choices of initial ocean fields, atmospheric forcing fields, air-sea flux parameterizations, vertical mixing parameterizations, and both horizontal and vertical resolutions. Alternate experiments are conducted by altering one single model attribute and comparing the results to SST analyses and moored ADCP current measurements to quantify the sensitivity to that attribute and identify where to concentrate model improvement efforts. Atmospheric forcing that does not resolve the eye and eyewall of the storm (scales.10 km) substantially degrades the ocean response. Ordering other model attributes from greatest to least sensitivity, ocean model initialization with regard to the accuracy of upper-ocean temperature-salinity profiles along with accurate location of ocean currents and eddies is the most important factor for ensuring good ocean model performance. Ocean dynamics ranks second in this energetic ocean region because a one-dimensional ocean model fails to capture important physical processes that affect SST cooling. Wind stress drag coefficient parameterizations that yield values exceeding 2.5×10-3 10-3 at high wind speeds or that remain<2.0×10-3 over all wind speeds reduce the realism of wind-driven current profiles and have a large impact on both SST cooling and the heat flux from ocean to atmosphere. Turbulent heat flux drag coefficient parameterizations substantially impact the surface heat flux while having little impact on SST cooling, which is primarily controlled by entrainment at the mixed layer base. Vertical mixing parameterizations have a moderate impact on SST cooling but a comparatively larger impact on surface heat flux. The impacts of altering the horizontal and vertical resolutions are small, with horizontal resolution of ≈10 km and vertical resolution of ≈10 m in the mixed layer being adequate. Optimal choices of all attributes for simulating the ocean response to Ivan are identified.

Original languageEnglish (US)
Pages (from-to)921-945
Number of pages25
JournalMonthly Weather Review
Volume139
Issue number3
DOIs
StatePublished - Mar 2011

Fingerprint

hurricane
sensitivity analysis
ocean
parameterization
sea surface temperature
heat flux
cooling
atmospheric forcing
drag coefficient
vertical mixing
mixed layer
Hurricane Ivan 2004
evaluation
energetics
wind velocity
wind-driven current
Acoustic Doppler Current Profiler
upper ocean
wind stress
tropical cyclone

Keywords

  • Hurricanes
  • Ocean models
  • Sea surfaced temperature
  • Sensitivity studies

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Evaluation and sensitivity analysis of an ocean model response to Hurricane Ivan. / Halliwell, Jr R.; Shay, Lynn K; Brewster, J. K.; Teague, W. J.

In: Monthly Weather Review, Vol. 139, No. 3, 03.2011, p. 921-945.

Research output: Contribution to journalArticle

Halliwell, Jr R. ; Shay, Lynn K ; Brewster, J. K. ; Teague, W. J. / Evaluation and sensitivity analysis of an ocean model response to Hurricane Ivan. In: Monthly Weather Review. 2011 ; Vol. 139, No. 3. pp. 921-945.
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