Evolving Oceanic and Atmospheric Boundary Layer Structure During Hurricanes Gustav and Ike: Progress

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Evolving Oceanic and Atmospheric Boundary Layer
Structure During Hurricanes Gustav and Ike
Progress

• L. K. Shay, E. Uhlhorn, R. Lumpkin, P. Meyers, B.
  Jaimes, J. Brewster, G. Halliwell, J. Zhang
• MPO/RSMAS, NOAA HRD, NOAA PhOD , CIMAS
• Appreciate efforts of NOAA AOC and the USAF 53rd
  Hurricane Hunters

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Research Objectives

• Observe the thermodynamical (thermal and
  momentum) response in the Loop Current (LC)/Warm
  and Cold Core Eddies (WCE, CCE) complex from
  temperature and current sampling
• Determine the relative roles of shear-induced
  mixing and advective tendencies by the background
  and wind-driven flows on the upper ocean thermal
  response
• Quantify the momentum, energy and vorticity
  balances of the LC complex and its response to
  strong TC forcing and,
• Examine the contribution of ocean features to
  surface stress and fluxes in the surface layer of
  the atmospheric within the direct forcing region,
  emphasizing the role of OML feedbacks on the
  atmospheric boundary layer.
• Note ONR sponsored cold wake experiments
  in Gilbert (88)

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Why Study Gulf of Mexico Hurricane?
FC
Oil Industry rigs and structures sustained
extensive damage in Katrina and Rita
(05) and Gustav and Ike (08).
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Surface Geostrophic Velocities (arrows) and SSH
(color) Before Gustav (left) and Ike
(right)-GFO/Jason/Envisat (http//isotherm.rsmas.m
iami.edu/heat)
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Track and Intensity of TCs Gustav and Ike Versus
AXBTs relative to OHC and 26oC Isotherm
Depth. Gustav 191 AXBTs 111
GPS Drifters
Floats Ike 216 AXBTs 111
GPS Drifters
Floats SMFR, SRA measurements.
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TCs Gustav and Ike NOAA WP-3D Sampling in
Aug/Sept 2008
Hurricane Gustav Hurricane Gustav Hurricane Gustav Hurricane Gustav Hurricane Ike Hurricane Ike Hurricane Ike Hurricane Ike
Date Flight GPS AXBT Date Flight GPS AXBT
28 Aug RF43 0 49(2) 08 Sep RF43 0 47(2)
29 Aug RF42 12(4) 16(0) 09 Sep RF42 19 6(0)
30 Aug RF43 9 19(2) 10 Sep RF42 17(1) 10(2)
31 Aug RF42 24 16(1) 10 Sep RF43 11 20(7)
31 Aug RF43 17(2) 19(1) 11 Sep RF42 16 10(1)
01 Sep RF43 44 19(0) 11 Sep RF43 10 22(3)
03 Sep RF43 4 54(4) 12 Sep RF42 21(2) 10(4)
12 Sep RF43 8 20(4)
15 Sep RF43 0 61(5)
Total 7 111(6) 191(10) 9 111(3) 216(28)
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Pre-Storm
Post-Storm Change in SST
Data courtesy of Dr. Chelle
Gentemann
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Gustav, OHC, HWIND
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Ike, OHC, HWIND
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OHC Approach Empirical Approach(Atlantic, East
Pacific-West Pac Next)

• Reduced gravity (g), H20, h (ocean mixed layer
  depth) GDEM V2.1
• Blend and objectively map SHA from Jason-1, GFO,
  and Envisat (9.9, 17 and 35-d repeat track).
• Infer H20 using mapped SHA and seasonal
  climatology.
• Estimate H26 relative to H20 (via ratio).
• Estimate OHC relative to 26oC using H26, h, and
  SST.

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Pre (left) and Post (right) and Post-Pre
(bottom) Ike OHC (color) and 26C isotherm depth
(contour) relative to the track and intensity Ike
from AXBTs. Notice the marked cooling in the
Gulf Common Water north and west of the LC.
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From Jaimes and Shay (MWR, 2009a)
6 kJ cm-2
22 m
mixed layer depth
114 kJ cm-2
68 m
81 m
122 m
26oC
246 m
Reduced negative feedback in warm core eddies
20oC
Hurricanes reach intensities closer to maximum
potential intensity.
Warm Eddy
Cold Eddy
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Gustav Drifters OHC (top panel) and Thermal
Structure (lower panel)
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Drifter Trajectories From Gustav (left) and Ike
(right)
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NOAA WP-3D profiling over MMS Moorings (In
collaboration with AOML HRD, AOC, TPC, NCEP)
Deliverables include V, T, S profiles to 1000 m
_at_ 2-m resolution. Surface winds (SFMR, GPS)
provided by HRD. Atmospheric profiles of V, T and
RH _at_ 5-m resolution.

• Goal To observe and improve our understanding of
  the LC response to the near-surface wind
  structure during TC passages. Specific
  objectives are
• Determine the oceanic response of the LC to TC
  forcing and,
• Influence of the LC response on the atmospheric
  boundary layer and intensity.

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Summary Quality ocean data needed for coupled
models!

• Approach serves as the prototype for coupled
  ocean/atmosphere measurements.
• Combine adaptive aircraft surveys with moored,
  drifter and ship based measurements as part of
  the MMS Dynamics of the Loop Current Study with
  the NOAA HFIP (AOML, NCEP), NSF and NASA
  (leveraging assets this year).
• Negative feedback (cooling/mixing induced by
  strong winds and CCR) as opposed to positive
  feedback over the LC/ WCR. Need to update OHC
  climatology in Atlantic basin.
• SST modulated by warm and cold ocean features
  that have to be properly initialized in ocean
  models and mixing processes-impact fluxes (more
  on this in Ivan Talk).
• Both temperature and current measurements needed
  to assess mixing schemes, fluxes and evaluate
  initialization schemes. Expendables (AXCP,
  AXCTD), drifters and floats required for
  satellite and oceanic and coupled model
  evaluations.