Objective Verification of CPC Outlooks
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Transcript of Objective Verification of CPC Outlooks
Objective Verification of CPC Outlooks
Michael Halpert
Climate Prediction Center
Outline
• Motivation
• Data
• Procedure
• Results
• Future Plans
Verification at CPC
Historically, CPC has verified ERF and LRF at first order stations
Forecasts made at 77 (out of 117) stations, 45 correct.Heidke Skill Score = 37.7%
Monitoring Data Sets
Temperature• ~5000 stations/day: RFC,
HADS, CADB• 0.5 x 0.5 degree resolution• 20°- 60°N, 140° - 60°W,
Conus only• Mid – Midnight window• Daily Max + Min/2• SD Quality Control check Temperature Station Locations
Monitoring Temperature
90 Day Mean/Anomaly
Precipitation Station Locations
Monitoring Data Sets
Precipitation• ~8000 stations/day: RFC,
HADS, CADB, SNOTEL, Mexican data
• 0.25 x 0.25 deg resolution• 10°- 60°N, 140° - 60°W,
Conus/Mexico• 12Z – 12Z window• QC: SD, buddy, Duplicate,
Nexrad checks
Monitoring Precipitation
2° x 2° Grid
20° - 56°N, 130° - 60°W, 232 valid points
Temperature Analysis
Procedure
Calculate means and tercile limits for all 232 grid boxes based on 1971-2000 base period
Tercile limits calculated as 0.43 SD for temperature; 33rd and 67th percentile (based on gamma) for precipitation
January – March Temperature Difference (Upper – Lower)
Procedure
• Characterize seasonal mean temperature and total precipitation as above, near, or below average.
Procedure
• Compare verification field to forecast
DJF Verification Grid DJF Forecast Grid
Seasonal OutlookDec 2005 – Feb 2006
Seasonal OutlookDec 2005 – Feb 2006
Heidke = 77, Coverage = 73%
Heidke = 82, Coverage = 64%
All Non-EC % Cov 37.6 71.0 53.0
April – June 2006 Temperature
All Non-EC % Cov 27.6 48.1 57.3
April – June 2006 Temperature
Temperature Skill ScoresGridded vs. Stations ( non-EC)
Gridded Score – 23.7 Station Score – 24.2
All Non-EC % Cov 2.6 5.9 43.6
April – June 2006 Precipitation
All Non-EC % Cov 14.9 39.7 37.5
April – June 2006 Precipitation
June 2006 TOfficial, Update, Observations OBS
UPD0.5 Lead
Off. Up. ChangeAll Stations 18.4 33.3 +14.9 Non-EC: 56.6 65.0 +8.4 % Cov: 32.5 51.3 +18.8
Off. Up. ChangeAll Stations 18.8 25.4 +6.6 Non-EC: 48.3 43.1 -5.2% Cov: 38.8 59.1 +20.3
June 2006 TOfficial, Update, Observations
OBS
UPD
0.5 Lead
Gridded verification makes tool verification simple
JJA 2006 Temperature
JJA 2006 Temperature
Official – 60
Consolidation – 58.2
January – March 1998 Temperature
Official – 37.3
Consolidation – 51.5
Temperature Heidke Skill ScoresOfficial vs. Consolidation (non-EC)
Official – 23.7
Consolidation – 27.6
Temperature Heidke Skill ScoresOfficial vs. Consolidation (all)
Official – 11.4
Consolidation – 18.4
Precipitation Heidke Skill ScoresOfficial vs. Consolidation (non-EC)
Official – 5.3
Consolidation – 12.4
Precipitation Heidke Skill ScoresOfficial vs. Consolidation (all)
Official – 1.4
Consolidation – 3.1
Future Plans
Seasonal/monthly
• Verification of tools
• Ranked Probability Skill Score
• Conversion of tools to 2x2 grid
Future Plans
Extended Range
• Verification of forecasts
• Development of 5 and 7 day data sets
• Precipitation Complications
• Verification of tools
• RPSS
• Development of tercile limits