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Mike Fiorino 1 michael.fiorino@noaa National Hurricane Center Miami, FL 7 March 2007

Performance of the ECMWF High-Resolution Global Model during the 2006 Northern Hemisphere Season and Impact on CONsensus. Mike Fiorino 1 michael.fiorino@noaa.gov National Hurricane Center Miami, FL 7 March 2007 1 CDR USN(RC), CNE-C6F DET 802 Atlanta. Full Disclosure….

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Mike Fiorino 1 michael.fiorino@noaa National Hurricane Center Miami, FL 7 March 2007

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  1. Performance of the ECMWF High-Resolution Global Model during the 2006 Northern Hemisphere SeasonandImpact on CONsensus Mike Fiorino1 michael.fiorino@noaa.gov National Hurricane Center Miami, FL 7 March 2007 1CDR USN(RC), CNE-C6F DET 802 Atlanta

  2. Full Disclosure… • was “seconded” to ECMWF 1998-99 for their ERA-40 reanalysis project • Developed TC data assimilation techniques and TC model verification “schemes” • ECMWF is very much O2R vice R2O • Research is (wholly) driven by Operations except for the proverbial “42.9 stone” member of staff (e.g., Tim Palmer) • Operations = medium-range weather (10-15 d) = 5-d 500 AC + probability  seasonal… nothing to do with TCs…

  3. One of my takeaways from the 61st IHC… from my ONR S&T Program 38 days So What? Who Cares? from Bill Gray This is all well and good Mike, but why are you doing this? BLUF – Bottom Line Up Front BS Leverages/Losses yoUFunding a corollary

  4. Answer to Bill Gray … NHEM because model (track) skill varies with (low-freq) synoptic situation …… potential for dynamical model intensity forecast skill in high resolution solutions …

  5. LANT 2006 :: BLUFhuge trend in ECMWF skill with tau @ d+3/4/5 >> peers 72-h Vmax - Mean Abs Error - Bias d+3  d+5 ECMO06 > ECMO12 > CONU > OFCL

  6. EPAC 2006:: BLUFECMWF ~ peers except > d+4/5 OCFL > all models and CONU strong error compensation GFS -CTE bias (equatorward) GFDL +CTE bias (poleward) ECMWF actually better than in previous years in EPAC persistent slow bias for WNW moving storms…

  7. WPAC 2006:: BLUF ECMWF ~ peers except > d+3/4/5 ECMO12 as at the “level of incompetence” d+3 JTYM06 > ECMO12 >

  8. Summary of 2006 NHEM Model Errors • LANT • ECMWF medium-range track (MRT) skill high with low “perishability” – even +12h tracker has value • bias-corrected intensity forecast shows a glimmering of skill at the medium-range – benefit of high spatial resolution? yes and no… • EPAC • all models had poor skill, but ECMWF shows some MRT skill • strong error compensation between GFS and GFDL due to poor vortex initialization CON >> than individual model • WPAC • better and less variation in MRT skill of the models • ECMWF shows good MRT skill, but dreadful intensity errors ??? (meteorology)

  9. GTS ECMWF BUFR trackers – Data flowlatency ~ 0.5 h ECMWF JTWC UKMO FNMOC TOC NCEP/NCO NHC

  10. Timing Issuese.g., 00Z model -> 06Z forecast with 09Z initial posit • ECMWF Integrated Forecast System (IFS) • +6.0 h – Tl799L91 (N400, dx~25km) 1 deterministic run • +8.0 h – Tl399L62 (N200, dx~50km) 51-member EPS run • +8.1 h – TC TRACKERS for DET and EPS run • +8.5 h – TC trackers reach TOC/NCEP/FNMOC/NHC/JTWC • ECMWF 1deg fields at NCEP  NHC • +7.0 h – 120-h 1deg DET solutions available • NHC • forecast process starts +6.5 need CON by + 6.5 h • JTWC • forecast process starts +7.0 need CON by + 7.5 h • “on time” model trackers ≤ 6.5 h • “late” model trackers > 6.5 h

  11. Summary of ECMWF timing and prospects for 2007 NHEM season… ECMWF trackers “late”NCEP/NHC tracker of ECMWF 1deg semi “on-time” ECMWF working to decouple TC trackers from the EPS run, may be “on time” for 2007

  12. Impact on CON… The Goerss Laws of CON_orthe conditions when medium-range forecast error of CON_> models 1) models have similar skill – applies in both directions… 2) error tend to be decorrelated

  13. CONM – LANT 2006ontime v late v all (CONM) 72 h ecmo06 > ecmo12 > conm >> conu  contributes to CON, but not always … sampling problem late taus: model >> peers, CON < best model early taus: model << peers, CON degraded

  14. CONM – EPAC 2006ontime v late v all (CONM) ecmo06 & ecmo12 ~ other models but contributes because of error decorrelation model ~ peers, CON > best modelerror compensation

  15. CONM – WPAC 2006ontime v late v all (CONM) big impact at d+5 model ~ peers, big contribution to CON at all taus

  16. Summary and some Speculation… • ECMWF makes positive contribution to CON > current baseline CON at the medium-range • exception was the LANT because it was much better than other members (Goerss CON rule 1) • Performance varies by basin  synoptic pattern  subtropical ridge/midlat baroclinic activity • ECMWF very good for storms influenced by the midlats • hi-res solution showing intensity prediction skill at the medium range, again for midlats • Speculation – ECMWF will NOT do as well in 2007 in the LANT as in 2006…but will improve CON in all basins at the medium range …

  17. Feb 2005Commander Fiorino, what’s your forecast for my 2005 WESTPAC season?COMPACFLT Meteorologist It won’t be like 2004 Captain…

  18. NHEM TC activity anomalies 2003-2006 • 2006 ∟ 2005 • WPAC year-to- year shifts > EPAC/LANT • 2006 WPAC: strong STR – 5 hits on the PI • 2006 LANT: weaker STR, more midlat • 2006 EPAC: N tracks, synoptic-scale land effects

  19. sometimes the magic works, and sometimes it doesn’t…The Goerss Second Law of TC model skill … partly because model skill does vary with the low-freq synoptic pattern implied by the TC activity anomalies …

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