NOAA’s Climate Prediction Center &*Environmental Modeling Center
Camp Springs, MD 20746
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
Table of Contents
Motivation
Model and experiments
Results, explanations, & summary
Future work
Yang and Lau (1998; J. Climate)
Motivation
NCEP Eta Regional Climate ModelResolution: 32-km in horizontal; 45 levels in verticalDomain: 10N-90N, 164W-58W
Noah Land Model 2.3, with 4 soil layersImplemented in Operational NCEP Eta ModelImplemented in NCEP Regional Reanalysis
Boundary conditions: NCEP/NCAR Global Reanalysis Initial conditions: NCEP/NCAR Global Reanalysis U.S. Air Force daily analysis of snow depthInitial land states: NCEP Regional Reanalysis
Model
Period: May-August of 1988 and 1993Starting months: AprilLength of integrations: 4 monthsNumber of ensemble members: 5SST, surface albedo, and greenness: Updated daily
Data of verifications: NCEP Regional Reanalysis; NCEP Land Data Assimilation System; CPC Unified Precipitation; and Global Telecommunications
Experiments
Soil moisture as surface boundary forcing in sensitivity experiments:3-hourly meansDaily meansWeekly means
Results I: Control Runs
Model-observation comparison
Precipitation (1993-1988)
Eta
RR CPC
Surface Temperature (1993-1988)
Eta
RR GTS
Soil Moisture (1993-1988)
LDAS data from Dr. Yun Fan
Results II: Sensitivity Experiments
Soil moisture as surface boundary forcing:3-hourly means
Daily meansWeekly means
Roles of diurnal cycle & sub-synoptic variability of soil moisture
JJA 1988Precip
3 Hourly
3H-Daily
3H-Weekly
Ts
TsJJA 1988T850
3 Hourly
3H-Daily
3H-Weekly
850-mb Winds
JJA 1988
3H-Weekly
3H-Daily
3 Hourly
Precip of JJA 1988 Precip of JJA 1993
3 Hourly
3H-Daily
3H-Weekly
3H-Weekly
Ts of JJA 1988 Ts of JJA 1993
3 Hourly
3H-Daily
3H-Weekly
T850 of JJA 1988 T850 of JJA 1993
3 Hourly
3H-Daily
3H-Weekly
JJA 1988
JJA 1993
3 Hourly
3H-Daily
3H-Weekly
Explanations
• 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.)
Summary
Future WorkImpact of the spatial structure of soil moisture