A Look at Climate Prediction Center

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Impact of High-Frequency Variability of Soil
Moisture on Seasonal Precipitation
Song Yang, S.-H. Yoo R. Yang, K. Mitchell, H.
van den Dool, and R. W. Higgins
NOAAs Climate Prediction Center Environmental
Modeling Center Camp Springs, MD 20746
Table of Contents
Motivation Model and experiments Results,
explanations, summary Future work
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Motivation
Yang and Lau (1998 J. Climate)
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Model
NCEP Eta Regional Climate Model Resolution 32-km
in horizontal 45 levels in vertical Domain 10N
-90N, 164W-58W Noah Land Model 2.3, with 4 soil
layers Implemented in Operational NCEP Eta
Model Implemented in NCEP Regional
Reanalysis Boundary conditions NCEP/NCAR Global
Reanalysis Initial conditions NCEP/NCAR Global
Reanalysis U.S.
Air Force daily analysis of snow depth Initial
land states NCEP Regional Reanalysis
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Experiments
Period May-August of 1988 and 1993 Starting
months April Length of integrations 4
months Number of ensemble members 5 SST,
surface albedo, and greenness Updated
daily Data of verifications NCEP Regional
Reanalysis NCEP Land Data Assimilation
System CPC Unified Precipitation and
Global Telecommunications
Soil moisture as surface boundary forcing in
sensitivity experiments 3-hourly means Daily
means Weekly means
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Results I Control Runs
Model-observation comparison
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Precipitation (1993-1988)
Eta
RR
CPC
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Surface Temperature (1993-1988)
Eta
RR
GTS
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Soil Moisture (1993-1988)
LDAS data from Dr. Yun Fan
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Results II Sensitivity Experiments
Roles of diurnal cycle sub-synoptic variability
of soil moisture
Soil moisture as surface boundary
forcing 3-hourly means Daily means Weekly means
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JJA 1988
Precip
3 Hourly
3H-Daily
3H-Weekly
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JJA 1988
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3 Hourly
850-mb Winds JJA 1988
3H-Daily
3H-Weekly
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Precip of JJA 1988
3 Hourly
3H-Daily
3H-Weekly
3H-Weekly
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Ts of JJA 1988
Ts of JJA 1993
3 Hourly
3H-Daily
3H-Weekly
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T850 of JJA 1988
T850 of JJA 1993
3 Hourly
3H-Daily
3H-Weekly
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3 Hourly
JJA 1988
JJA 1993
3H-Daily
3H-Weekly
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Explanations
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Summary

• Reasonable performance by Eta
• Impact of sub-synoptic soil moisture variability
• HF var. of soil moisture changes seasonal means
  of precip.
• Different roles between 1988 and 1993
• Importance of diurnal cycle
• Dynamical consistence
• Explanation (water and heat fluxes, instability,
  etc.)

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Future Work
Impact of the spatial structure of soil moisture