Evaluating Skill in Ocean Model Parameterizations: Taylor Diagrams

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Evaluating Skill in Ocean Model
Parameterizations Taylor Diagrams

• Lynn (Nick) Shay and G. Halliwell
• MPO, RSMAS, Univ. of Miami
• PhOD, AOML, NOAA
• http//isotherm.rsmas.miami.edu/nick
• HFIP Observations and Modeling Teams

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Tis the Season.
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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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Ocean Structure Gulf Versus East Pacific
Strong vertical temperature, salinity and density
gradients at base of OML in EPAC Implications
for mixingand ocean (SST) cooling.
N20 cph
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Differentiated cooling in the LC system (Jaimes
and Shay, MWR, 2009)
?T -1oC
?T -4.5oC
Loop Current
Shedding front
?T -0.5oC
Warm core eddy
Cluster-averaged temperature profiles
vertical shear (s-2)
ageostrophic velocity (cm s-1)
ageostrophic KE (cm2 s-2)
Richardson number
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Taylor Diagrams
Taylor diagram
R
E
Taylor, K., 2001 JGR, 106, D7,
7183-7192
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Taylor Diagram Skill Score
Taylor diagram
S-isolines 0.1 intervals, grey shading
Taylor, K., 2001 JGR, 106, D7, 7183-7192
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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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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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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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Regression XBT Transect East Pacific Ocean
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XBT Transect-East Pacific
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Equivalent OHC and Juliette (2001)
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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 (Shay et al. 2009)
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NOAA WP-3D Profiling over MMS Moorings
(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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Progress 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.
• Taylor Diagrams collapse Standard Deviation,
  Correlation Indices and RMS Differences into one
  representation relative to an observation of
  current, temperatures, winds, humidities,
  variance etc to assess model performance.
• Estimate skill by combining standard deviations
  and correlations.
• In Ivan case, 14 sets of model simulations were
  made differing in only one aspect at a time.
  Approach shows sensitivity and allows us to
  isolate physics (Even a 1-D versus 3-D Ocean!)
• Applying same approach to OHC variability in
  assessing uncertainties in satellite retrievals
  using in situ data as truth.
• Field programs to acquire 3-D data