Report on CTB CFS Test and Evaluation Team Activities

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Report on CTB CFS Test and Evaluation Team
Activities Team Leads Jae-Kyung Schemm and
Shrinivas Moorthi CPC and EMC,
NCEP/NWS/NOAA 32nd Climate Diagnostics and
Prediction Workshop October 22-26,
2007 Tallahassee, Florida
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• CFS Test and Evaluation Team
• - One of three components of CTB Project
• Team Mission
• Perform sensitivity experiments and evaluate the
  results.
• Experiments are designed to accelerate the
  development of
• CFS.
• Team Membership EMC and CPC federal and contract
  employees,
• and CTB funded investigators.
• Two types of experiments are performed on the CTB
  computer
• i. CTB funded projects
• ii. Internal projects proposed by CTB T E
  Team members,
• reviewed and approved by CST
• Balance will shift from ii) to i) as CTB grants
  increase.

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• FY07 accomplishments
• - 17 experiments proposed and approved by CST.
• - Most experiments finished and preliminary
• evaluation done. (4 presentations and 7
  posters)
• - CTB TE Team has fostered successful
  collaboration
• between EMC and CPC.
• - This should evolve further in FY08 as the
  competitive
• grants program grows and additional PIs join
  CTB.
• FY07 experiments have provided some insight and
  recommendations
• towards the next CFS and CFS RR.

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Selected results from experiments and evaluations
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• Test of RRTM shortwave radiation code (Hou and
  Saha)
• AER RRTM-SW radiation scheme has been
  incorporated into the new GFS/CFS. Also included
  are other physical processes such as solar-cycle,
  aerosol effect (including historical volcanic
  origin) and historical CO2.
• T126/MOM3 version was run from 01/01/1948 for 60
  years.
• Comparison of global mean SST, T2m anomalies,
  and global map of SST climatology shows promising
  improvement over the control model.
• - Served as a benchmark for other GFS evaluations.

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• CFS subseasonal hindcast run (Vintzileos and Pan
  )
• - reported by A. Vintzileos in this session
• 60-day forecast runs in 5-day intervals during
  May-August,
• 2002-2006.
• 2. Impact of horizontal resolution (T62, T126,
  T254)
• and initial condition (GDAS, CDAS2) examined.
• Principal findings and recommendations
• 1. New CFS needs to be accompanied by its own
  reanalysis.
• 2. Impact of model resolution detected in
  tropical Atlantic and
• Africa - downscaling of operational forecasts
  could be
• beneficial in those sectors.

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• Rerun of the offline Noah Land Model for
  1948-2006
• (Fan and van den Dool)
• Improvements in the model, vegetation class table
  and input precipitation datasets.
• Homogeneous input for both retrospective (from
  1948) and real-time analysis.
• Main findings
• Soil moisture anomalies and annual cycles are
  improved in top two layers,
• but the dry end of annual cycles are about 12
  month late.
• Anomalies in lower layers are comparable with old
  run, however,
• the amplitudes of annual cycles much larger than
  Obs as in older version.
• Slight changes in evaporation and runoff are
  found in northern US.
• About 1020 mm/mon increase (decrease) in
  evaporation (runoff)
• is seen in southeastern US.

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• T382 CFS runs for hurricane season (Saha, Thiaw)
• AGCM - 2007 operational NCEP GFS
• LSM - Noah LSM
• OGCM - GFDL MOM3
• All runs initialized with NCEP/DOE R2 and NCEP
  GODAS at 0Z, May 15, 1981-2006.
• AGCM spatial resolution in T382L64. Companion
  runs made in T126L64 and T62L64 also.
• This experiment has been extensively analyzed by
  the Evaluation Team members.
• 1 presentation and 3 posters on tropical storms
  and monsoon prediction.

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Examples of Storm Tracks for 4 NH Basins
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Atlantic Basin
Correlations Total r0.38 81-93
r0.15 94-06 r0.37
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Eastern Pacific Basin
Correlations Total r0.16 81-93
r0.04 94-06 r0.02
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T62 T126 T382 OBS
New CFS Runs 3 different resolutions ICs May 15
(1 member)
SST
SSTA in MDR ASO 2 month lead
Correlation (CFS, OBS)
Linear trend removed
Co
.75 .69 .74
.66 .54 .65
T62 T126 T382
T62 T126 T382
Year
Warming trend contributes to the high correlation.
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T62 T126 T382 OBS
New CFS Runs 3 different resolutions ICs May 15
(1 member)
U200U850
U200U850 in MDR ASO 2 month lead
Correlation (CFS, OBS)
Linear trend removed
m/s
.62 .57 .48
.58 .34 .42
T62 T126 T382
T62 T126 T382
Year
Lower resolution better wind shear
(single run)
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• Summary
• CFS in T382 resolution exhibits fairly robust
  climatological
• seasonal cycle of tropical cyclone over four
  NH basins.
• Warming trend and intensification of hurricane
  activity in the
• Atlantic basin captured.
• Increased horizontal resolution may lead to
  improved vertical
• wind shear prediction over the Atlantic MDR.
• Ensemble members needed for better depiction of
  large scale
• circulation.
• Coupled air-sea interaction important

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• CFS E. Pacific SST bias corrections (Xie, Wang)
• Impact of radiation flux error over the
  Southeastern Pacific examined.
• SST bias reduced by half from surface
  radiation
• bias correction.

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• CFS hindcast rerun with corrected GODAS
• for 1981-1990 (W. Wang, Xue, Schemm)
• Reruns with June and December initial conditions
  -
• Evaluations on SST and atmospheric
  variables performed.
• Mean SST is reduced by 0.2-0.4 degree due to
  GODAS corrections - reduces warm biases but
  worsens cold biases, particularly for June ICs.
• Changes in precipitation bias are confined in the
  Tropics.
• SST hindcast skill is improved, most
  prominent in
• the Pacific and Indian Ocean for December
  ICs and in the Atlantic Ocean for June ICs.
• No significant changes in skill over North
  America for 2m temperature and precipitation.
• Provided analysis with April ICs for hurricane
  seasonal outlook issued in May 2007.

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SST Indices Hindcast Skill in 1981-2005 (red ?
improvement)
JAS
OND
JFM
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SST hindcast averaged in the hurricane main
development region (MDR) for July-November
starting from June 11-31 I.C.. The SST hindcast
is reduced (green) in 1981-1990 and increased
(red) in 1991-2005 due to GODAS corrections. CFS
realistically simulated the peaks of the index in
1987, 1995, 1998 and 2003-2005, and valleys in
1984-1986 and 1994, which suggests a potential
contribution of the CFS forecast for the
hurricane outlook.
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North America
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Summary CTB TE Team has fostered successful
collaboration between EMC and CPC. FY07
experiments provided some insight and
recommendations towards the next CFS and CFS RR.
This successful collaboration should evolve
further in FY08 with funded projects for the
next1 CFS.
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• For FY08
• - Main focus To participate in CFS reanalyasis
  and reforecasts
• - To experiment with and evaluate the impact of
  suggested changes to
  CFS by funded external proposals.