Evaluation of Upper Ocean Mixing Parameterizations

1
Evaluation of Upper Ocean Mixing Parameterizations

• S. Daniel Jacob1, Lynn K. Shay2 and George R.
  Halliwell2

1 GEST, UMBC/ NASA GSFC, Greenbelt, MD 20771 2
MPO, RSMAS, University of Miami, Miami, FL
33149 3 NASA GSFC , Greenbelt, MD 20771
FOCUS EMC Coupled Intensity Prediction Modeling
Acknowledgements A. Wallcraft (NRL Stennis), M.
Powell (NOAA HRD), O. M. Smedstad (Planning
Systems Inc), David LeVine (NASA/GSFC), TPC
Points of Contact Michelle Mainelli and Miles
Lawrence
2
Upper Ocean Mixing and Hurricane Intensity

• Based on Observational Analysis (Jacob et al.,
  JPO 2000)
• Entrainment is the dominant mechanism in the
  mixed layer cooling.
• Mixed layer heat and mass budgets strongly depend
  upon the entrainment scheme used.
• Numerical Modeling (Jacob and Shay, JPO, 2003)
• Measured and simulated quantities based on
  different hypothesis are used to compute
  entrainment mixing.
• Four bulk or slab schemes in using MICOM

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MOVIE 1
KT
Gaspar
DDF
PRT
4
Hycom Q Movie
Gaspar
KPP
MY2.5
PWP
5
2 Rmax
No Precip
Precip
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OBJECTIVES

• Evaluate and Validate Mixing Schemes to identify
  the most appropriate parameterizations for use in
  coupled prediction model.
• Schemes in the Hybrid Coordinate Ocean Model
• K Profile Parameterization (Large et al. 1994)
• Gaspar (1988)
• Price et al. (1986) scheme.
• Mellor and Yamada (1974) Level 2.5 scheme
• Canuto et al. (2001, 2002)
• Compare Simulations to Observations
• Gilbert (1988)
• Isidore (2002)
• Lili (2002)
• 353 Temperature Profiles from AXBTs, AXCPs and
  AXCTDs
• 208 Current Profiles from AXCPs
• 102 Salinity Profiles from AXCTD

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GILBERT UPPER OCEAN RESPONSE EXPERIMENT
Shay et al. JGR 1992
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ISIDORE
Shay and Uhlhorn Poster
60 AXBTs 77 AXCPs 70 AXCTDs
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LILI
83 AXBTs 57 AXCPs 32 AXCTDs
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Model Configurations

• Gilbert (1988)
• Prior HYCOM/ MICOM configuration on Mercator grid
  at 0.07 resolution at the equator.
• Closed/ Buffer Zone at the boundaries.
• Simulations from 14 Sep 1988 to 20 Sep 1988.
• Isidore (2002) and Lili (2002)
• Domain includes Caribbean Sea and the Gulf of
  Mexico.
• Treated as a single case with 20 day integration
  for each mixing parameterization.
• Configured as a nest of the basin scale HYCOM
  that provides conditions at the open boundaries.

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Initial Conditions

• Gilbert
• Initial Conditions derived from Yearday 200 data
  in 1988
• Eddy location is accurate to 0.2
• Strength of the Eddy is consistent with
  Observations
• Depth of the 26 C isotherm is about 10 m
  shallower
• Pre-Isidore conditions are derived from the
  Basin Scale HYCOM
• Altimeter data assimilated Gulf Stream/LC
  located correctly
• Depth of the 26 C isotherm is shallower in
  these fields
• Detailed evaluation Poster by Dr. Halliwell et
  al.

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Temperature-Salinity Diagram
Sea Surface Height Field
LCW
GCW
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Sea Surface Height Anomaly and Ocean Heat Content
19 Sept 2002
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WIND FIELD STRUCTURE 16 SEP 88 06UTC

• HWIND Analysis
• Flight Level Reduced
• Buoy
• ECMWF
• 3 Hourly

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WIND FIELD STRUCTURE 22 SEP 02 12UTC

• 3 hourly Inner Core Winds from Dr. M. Powell,
  HRD
• NCEP Winds
• Resample to 1 Hr

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KPP
PWP
MY
GISS
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KPP y 1.05x 1.75 ?d 0.28 C sd 1.19 C
Gaspar y 0.68x 9.0 ?d -0.40 C sd
0.94 C
PWP y 1.40x 12.2 ?d 1.52 C sd 2.30 C
MY y 0.94x 1.68 ?d -0.14 C sd 1.12
C
GISS y 1.18x - 5.4 ?d 0.56 C sd
1.38 C
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KPP
GISS
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SUMMARY

• Two High Resolution HYCOM configurations are used
  to investigate the oceanic mixing
  parameterizations for use in coupled predictive
  models with a EMC focus.
• Initial conditions and forcing for the three
  cases compare well with the observed data.
• Simulations suggest that the KT scheme simulates
  warmer mixed layers in contrast PWP scheme that
  is much cooler. The higher order schemes perform
  in the middle in all cases.
• Comparisons with data indicates better
  performance of KPP and MY2.5 for the Gilbert
  case. Initial comparisons indicate a slightly
  better statistics for the KPP scheme in Isidore
  and Lili cases.
• Further comparison and investigation of
  sensitivity to vertical resolution of the model
  is in progress. Initial simulations in the
  Gilbert case do not show much sensitivity,
  although oceanic mixed layer depth is resolved
  better with higher resolution.

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Future Work

• Detailed comparison and sensitivity of the
  comparison statistics to the vertical resolution
  of the model for Isidore and Lili cases.
• Comparison of
• Mixed Layer Depths
• Currents
• Shear/ Richardson Numbers/ Diffusivities
• Salinity dependant stability
• TRANSITION with NCEP deploying HYCOM
  operationally as the ocean component, this is
  straight forward.
• Only three storms Additional measurements and
  further validation required to improve
  confidence.
• A post-season evaluation of the model fields is
  necessary. Requires operational ocean response
  observations in the near future to improve
  statistical base of comparisons.