The Operational NCEP GODAS:

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The Operational NCEP GODAS Evaluation,
Application and Web Site Yan Xue Climate
Prediction Center, NCEP/NOAA David Behringer
Environmental Modeling Center, NCEP/NOAA
NOAA Climate Observation Program 3rd Annual
System Review, April 25, 2005

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MODEL RUNS

• GODAS
• RA6
• Simul (same as GODAS except no data
  assimilation)

VERIFICATION

• Dependent Data
• TAO temperature profiles
• World Ocean Atlas 2001 (WOA01)
• Independent Data
• Tide Gauge (sea level)
• Gregory Johnsons CTD (salinity)
• Peter Niilers drifter current (velocity)
• TAO ADCP (velocity)
• Altimetry sea level

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Spurious Cooling Trend in GODAS
Surface Velocity in GODAS
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Temp Diff GODAS RA6 at 105 meter
1980
Warm biases before 1990 ?
1990
2003
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Simul(1979-1991) WOA01
Simul(1992-2003) WOA01
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GODAS(1979-1991) WOA01
GODAS(1992-2003) WOA01
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XBT data increases sharply in 1990
TAO data increases sharply in 1993
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NCEPs CFS SST forecast Clim Diff
Lead 1 Month
Lead 6 Month
OI SST
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Drifter Current
GODAS Current
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Correlation
RMS Diff
of pentads
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Summary

• Spurious cooling trend in GODAS is caused by the
  warm biases in simulation that have not been
  effectively corrected before 1990 when in situ
  observations are sparse.
• Large errors remain in midlatitude Southern
  Hemisphere where more in situ observations are
  needed.
• Surface zonal velocity compares well with surface
  drifter velocity except in the equatorial Pacific.

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Applications of GODAS at NCEP

• CFS model uses GODAS as oceanic initial
  conditions.
• Weekly ENSO Update uses GODAS pentad
  temperature and sea level fields to monitor
  intraseasonal oceanic variability.
• Climate Diagnostic Bulletin uses GODAS monthly
  temperature and sea level fields to assess
  interannual oceanic variability.
• Markov model uses GODAS monthly sea level field
  as predictor.
• CCA ENSO model uses GODAS monthly sea level and
  depth of 20 degree as predictors.

• Explore ocean indices for ENSO monitoring
• Study MJO-ENSO connection
• Study coupled ocean-atmospheric modes in the
  Tropical Atlantic Ocean.

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Ocean Indices for ENSO Monitoring

• Recharge and Discharge ENSO theory ---
• heat storage within 120OE-110OW and 4.5OS-4.5ON
• WWV
• warm water volume above depth of 20OC
• HC
• averaged temperature in the top 300 meter
• SL
• sea level

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Lead NINO3.4
Lag NINO3.4
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CPCs Weekly ENSO Update
Oceanic Kelvin Waves
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MJO-related Oceanic Kelvin Waves and the ENSO
Cycle A Study with the NCEP Global Ocean Data
Assimilation System Kyong-Hwan Seo and Yan Xue,
accepted by GRL
EEOF 1
Depth of 20OC
EEOF 2
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SVKW seasonal variance of Kelvin wave
NINO3.4
Heat Content averaged temperature in top 300
meter within equatorial belt
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HC
HC tendency
NINO3.4 tendency
NINO3.4
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GODAS Web Site in Plan

• NOAAs Office of Climate Observation sponsors
  CPC to host a web site for GODAS
• Objectives
• Monitor different aspects of oceanic climate
  variability
• Assess benefits of NOAAs extensive investment in
  global ocean observing system
• Disseminate GODAS products to a broad user
  community
• Involve research community in assessment and
  improvement of GODAS

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GODAS Web Site Design

• Pentad products (archive past 3 months)
• Model output (SST, subsurface temperature, heat
  content, depth of 20OC, mixed layer depth, ocean
  current, wind stress, total heat flux, total
  fresh water flux)
• Data distribution (XBT, TAO, ARGO)
• Model-data intercomparison
• Monthly products (archive 1979-current years )
• Model output
• Data distribution
• Model-data intercomparison
• Climatology
• Skill assessment

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GODAS Climatology

• Because there is a warm bias in GODAS before
  early 1990s, the base period is 1992-2003.
• Pentad climatology
• Pentad mean over 1992-2003
• Take first three harmonics
• Monthly climatology
• Average monthly climatology from pentad
  climatology

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60OE
140OW
30OW
Zonal Velocity
10S
10S
10S
10N
10N
10N
30N
30N
30N
30S
30S
30S
Meridional Velocity
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Mean Sea Surface Temperature
GODAS
GODAS-WOA2001
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Mean Sea Surface Salinity
GODAS
GODAS-WOA2001
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Future Works

• Web site for GODAS
• Impacts of boundary forcing errors on GODAS
• Momentum fluxes AMIP, CDAS2, ERA40 and FSU
• E-P fluxes AMIP, CDAS2, CMAP and GPCP Prec.
• Impacts of altimetry sea level on GODAS
• Impacts of geostrophic adjustment on GODAS
• Applications of GODAS

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SIM
RA6
GODAS
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from 1992-2000 mean
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Correlation
RMS Diff
of pentads