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Verifications of CPC Seasonal Forecasts from 1995-2007

Verifications of CPC Seasonal Forecasts from 1995-2007. Arun Kumar Peitao Peng Climate Prediction Center 32 nd CDPW, Tallahassee, FL. CPC’s Seasonal Forecasts. Have been issued in their current format since January 1995

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Verifications of CPC Seasonal Forecasts from 1995-2007

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  1. Verifications of CPC Seasonal Forecasts from 1995-2007 Arun Kumar Peitao Peng Climate Prediction Center 32nd CDPW, Tallahassee, FL

  2. CPC’s Seasonal Forecasts • Have been issued in their current format since January 1995 • Are issued with a lead time of ~15 days, and are made for next 13 overlapping seasons • Are for surface temperature and precipitation (over the contiguous U.S. & Alaska) • Are based on a combination of empirical tools (CCA, OCN, SMLR) and a dynamical coupled model (currently the CFS) • Major changes have been • 2 upgrades in the dynamical prediction system since 1995 • Introduction of an objective consolidation technique in January 2006

  3. Outline • Format of Seasonal Forecasts • Verifications of seasonal forecasts • Different skill measures • Temporal and spatial distribution of skill measures • Attributing skill to different predictors • Cost-Loss analysis of forecasts • Future plans

  4. Format of Seasonal Forecasts

  5. Today’s Special at the Café Verification are… • Surface temperature over the contiguous U.S. • Various Skill Measures • Heidke • RPSS • Reliability • ROC • Sample size: All (145 seasons); Warm and cold season (60 seasons);individual season (12 seasons)

  6. Heidke Skill Score (HSS): Temporal Variations Seasonal Cycle (HSS; % Area Covered) 11 MRM

  7. Heidke Skill Score: Spatial Variations

  8. HSS vs. Number of Times Forecast was Issued ? Not sure what kind of relationship to expect? Forecast made more frequently (always higher confidence in the signal)  Higher skill? Forecast made less frequently (but made only when there is signal) Higher skill?

  9. Heidke Skill Score: Seasonal Contrast

  10. RPSS: Spatial and Temporal Variations

  11. Predicted and Observed Frequency Distribution for the Above Normal Category Frequency Distribution: Surface Temp; Upper Tercile (above normal)

  12. Surface Temperature: Reliability

  13. Heidke Skill Score: Official vs. Consolidated 11 MRM 60% Improvement

  14. Heidke Skill Score: Official vs. Consolidated

  15. Future Plans • Complete the verification summary (precipitation; verification for individual tools;…) • Update the verification summary after the calendar year is over • Error bars on skill scores • Cost-Loss Analysis for different (decision) probability thresholds • Consider how to intelligently use this information from the user’s and forecaster’s perspective…

  16. Multiple Sources! Farmer Jones’ Dilemma What is the relevance of past skill information in the context of me using this SPECIFIC forecast?

  17. Solution to Farmer Jones’ Dilemma? Conditional Skill Estimates and Reliable Forecasts, but… Skill conditional to the expected state of predictors!!

  18. Backup Slides

  19. Surface Temperature: ROC Score

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