Verification of Seasonal Climate Prediction with the NCEP Seasonal Forecast GCM in 2001/2002

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Verification of Seasonal Climate Prediction with
the NCEP Seasonal Forecast GCM in 2001/2002

• Jae-Kyung E. Schemm
• Arun Kumar
• Huug van den Dool
• Masao Kanamitsu
• Climate Prediction Center
• NCEP/NWS/NOAA

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NCEP seasonal climate prediction system

• Description of AGCM
• Dynamics
• Global spectral configuration in T62L28
• Model physics
• Relaxed Arakawa-Schubert convection scheme
• M.-D. Chou short wave radiation
• M.-D. Chou long wave radiation
• Original Slingo-type cloud
• Tiedtke shallow convection
• Hong and Pan non-local diffusion
• Alpert, et al. gravity wave drag
• OSU land hydrology model
• Mean smoothed orography
• Leith horizontal diffusion on pressure surface

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NCEP seasonal climate prediction system

• 2. Production Suite
• For each month, 7-month prediction runs of 10
  member ensemble initialized in 1979 - 1999
  period.
• Initial conditions at 0Z and 12Z of first 5 days
  of month.
• Observed SST and climatological soil moisture as
  boundary conditions.
• Model climatology and climatological probability
  distribution based on the 1979-1999 cases.
• 7-month prediction runs of 20-member ensemble
  initialized at 0Z and 12Z of last 5-days of
  previous month and first 5-days of present month.
  
• Forecast SST from ocean model used as BC.
• Forecast anomaly determined with the model
  climatology -- model bias removed.

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Development in 2001-2002

• 1. Implementation of the seasonal prediction
  suite as part of the NWS operational production
  in December 2001.
• Data access
• ftp//tgprd.nws.noaa.gov/SL.us008001/ST.opnl/MT.
  clim_MR.hind
• ftp//tgprd.nws.noaa.gov/SL.us008001/ST.opnl/MT.
  clim_MR.fcst
• Additional ensemble runs with the constructed
  analog SST forecast.
• 3. EMC started working on the next generation
  coupled model system for seasonal prediction -
  parallel climate test suite with the operational
  GFS GCM.
• Ref. Websites
• http//www.emc.ncep.noaa.gov/cmb/atm_forecast
• http//www.cpc.ncep.noaa.gov/schemm/snfcst.html

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Anomaly Correlation of SFM Forecast 500 hPa
height PNA Region (2000-2002)
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Anomaly Correlation of SFM Forecast 2m
Temperature over US Region (2000-2002)
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Anomaly Correlation of SFM Forecast
Precipitation over US Region (2000-2002)
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Anomaly Correlation of CA SST Forecast Sep 79-99
ICsTropical Pacific Sector (15S-15N, 160E-80W)
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Anomaly Correlation of CA SST Forecast Sep 79-99
ICsNorth Pacific (20N-60N, 160E-140W)
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Anomaly Correlation of Seasonal Precipitation
Fcst with Sep. ICsBCs with Obs SST (left) and
CA Fcst SST (right)
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Anomaly Correlation of Seasonal 500 hPa Height
Fcst with Sep ICsBCs with Obs SST (left) and
CA Fcst SST (right)
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Summary

• NCEP SFM seasonal predictions evaluated for
  2000-2002 in terms of 2m temperature and
  precipitation over the continental US, and 500hPa
  height over the PNA sector. All variables exhibit
  modest skill of 0.2 in anomaly correlation
  scores in average over the two year period.
• Seasonal predictability is overestimated when it
  is based on GCM runs with observed SST as
  boundary condition. The anomaly correlation of
  winter season forecast was reduced considerably
  when forecast SST was utilized. The forecast SST
  was produced with the constructed analog method
  developed by van den Dool.