JHT Project: Evaluation and Improvement of Ocean Model Parameterizations for NCEP Operations Ivan

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JHT Project Evaluation and Improvement of Ocean
Model Parameterizations for NCEP Operations (Ivan)

• L. K. Shay, G. Halliwell, J.Brewster, C. Lozano,
  W. Teague
• MPO, RSMAS, Univ. of Miami
• EMC-NCEP
• Oceanography Department, NRL-Stennis
• http//isotherm.rsmas.miami.edu/nick

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JHT Project Objectives

• Ivan an example of negative feedback (cold wake
  cooling and Cold Core Ring) as opposed to less
  negative feedback (Loop Current/Warm Core Rings)
• By building on a previous JHT, specific
  objectives are
• optimizing spatial resolution that will permit
  the ocean model to run efficiently as possible
  without degrading the simulated response
• improving the initial background state provided
  to the ocean model
• improving the representation of vertical and
  horizontal friction and mixing
• generating realistic high-resolution atmospheric
  forcing fields necessary to achieve these
  objectives and
• Testing differing formulations of the drag
  coefficient (cd).

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MOTIVATION Ivan (2004) over the GOM SSH (cm)
from HYCOM (from Halliwell et al., MWR,
2008). SST Analyses
Northern Cyclone
Southern Cyclone
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Ivans Track and Intensity Relative to OHC
(left) NRL SEED Mooring Locations in Northern
Gulf of Mexico Relative to Bottom Depth (Right)
(Teague et al., JPO, 2007).
14 ADCP moorings- Focus here in Array 9.
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NRL Mooring Specifics (Teague et al., JPO,
2007).Note ADCP provides absolute velocity
(u,v,w)
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HYbrid Coordinate Ocean Model (HYCOM)Hurricane
Ivan Simulations 10 Sept-6 Oct 04

• Configuration
• 0.04 Mercator grid, Gulf of Mexico domain
• No data assimilation performed
• Initial and boundary conditions from U.S. Navy
  HYCOM ocean nowcast-forecast system
• Data assimilative ocean nowcast
• Navy Coupled Ocean Data Assimilation (NCODA)
  assimilation
• Atmospheric Forcing
• Navy 27 km COAMPS atmospheric model
• Vector wind blended with higher resolution fields
  from HWIND
• Wind stress for HWIND calculated using Donelan cd

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Hurricane Ivan Modeling Experiment Summary
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Intense Forcing (upper) and Relaxation Stages
(lower) for NRL SEED moorings 7-14 7-10 Red
500 m 11-14 Yellow1000 m (Teague et al. JPO,
2007).

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M9 (1.5 Rmax) Observed and Near-Inertial Current
Shear Response (Rmax 32 km)
Normalized shear by 10-2 s-1
based on Isidore/Lili
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RMS SST (oC) Differences


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TMI and KPP SST Comparisons
Pre Ivan SST Post-Ivan SST Pre-Post
Ivan ?SST

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Observed/Simulated Current Response at M9 (1.5
Rmax) from 7 Experiments Halliwell et al., MWR,
(2009) Below cd using ocean response as a tracer
in Shay and Jacob (2006)

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Current Time Series
Comparisons _at_ 1.5 Rmax
U (east-west)
V (north-south)

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Taylor Diag., simulations vs. baseline SST
v Current at M9 (1.5Rmax). (Halliwell et
al., MWR, 2009)

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Taylor Diag., simulations vs. observations SST
v Current at M9 (1.5Rmax). (Halliwell et
al., MWR, 2009)

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Progress Summary and Blueprint For Future

• Ivan a clear example of negative feedback (wake
  cooling/mixing induced by strong winds and Cold
  Core Ring) as opposed to positive feedback over
  the Loop Current and Warm Core Rings.
• SST modulated by warm and cold ocean features
  that have to be properly initialized in ocean
  models and mixing. Data assimilation schemes are
  essential!
• Trifecta Katrina, Rita and Wilma is next.
• Temperatures and currents needed to assess mixing
  schemes and evaluate initialization schemes. Both
  Eulerian (AXCP, AXCTD, moorings) and Lagrangian
  (drifters, floats) needed Targeted Obs in
  storm coordinates!
• Working with MMS on 5-year Loop Current Dynamical
  Study, NOAA HFIP and NSF.

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Sampling Pattern AXCTDs and Drifters relative to
OHC and Ritas track. Pre (15 Sep) and Post Rita
(26 Sep) WCR/CCR/ LC OHC and 26oC isotherm
depth. Vertical structure from AXCTDs (Jaimes
and Shay, MWR, 2009a)