Performance of the ECMWF High Resolution Global Model

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-C 6 F DET 802 Atlanta M. Fiorino : : IHC 61 st NOLA 20070307

Full Disclosure… n was “seconded” to ECMWF 1998 -99 for their ERA 40 reanalysis project n Developed TC data assimilation techniques and TC model verification “schemes” n ECMWF is very much O 2 R vice R 2 O n Research is (wholly) driven by Operations except for the proverbial “ 42. 9 stone” member of staff (e. g. , Tim Palmer) n Operations = medium-range weather (10 -15 d) = 5 d 500 AC + probability seasonal… nothing to do with TCs… M. Fiorino : : 61 st IHC 20070307 New Orleans, LA

One of my takeaways from the 61 st IHC… BLUF – Bottom Line Up Front a corollary BS Leverages/Losses yo. U Funding 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? M. Fiorino : : IHC 61 st NOLA 20070307

Answer to Bill Gray … NHEM because model (track) skill varies with (lowfreq) synoptic situation … … potential for dynamical model intensity forecast skill in high resolutions … M. Fiorino : : IHC 61 st NOLA 20070307

LANT 2006 : : BLUF huge trend in ECMWF skill with tau @ d+3/4/5 >> peers 72 -h Vmax - Mean Abs Error - Bias d+3 d+5 ECMO 06 > ECMO 12 > CONU > OFCL M. Fiorino : : 61 st IHC 20070307 New Orleans, LA

EPAC 2006: : BLUF ECMWF ~ 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… M. Fiorino : : 61 st IHC 20070307 New Orleans, LA

WPAC 2006: : BLUF ECMWF ~ peers except > d+3/4/5 ECMO 12 as at the “level of incompetence” d+3 JTYM 06 > ECMO 12 > M. Fiorino : : 61 st IHC 20070307 New Orleans, LA

Summary of 2006 NHEM Model Errors n LANT n n n EPAC n n n ECMWF medium-range track (MRT) skill high with low “perishability” – even +12 h tracker has value bias-corrected intensity forecast shows a glimmering of skill at the medium-range – benefit of high spatial resolution? yes and no… 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 n n better and less variation in MRT skill of the models ECMWF shows good MRT skill, but dreadful intensity errors ? ? ? (meteorology) M. Fiorino : : 61 st IHC 20070307 New Orleans, LA

ECMWF BUFR trackers – Data flow latency ~ 0. 5 h ECMWF JTWC UKMO GTS FNMOC TOC NCEP/NCO NHC M. Fiorino : : 61 st IHC 20070307 New Orleans, LA

Timing Issues e. g. , 00 Z model -> 06 Z forecast with 09 Z initial posit n ECMWF Integrated Forecast System (IFS) n n +6. 0 h – Tl 799 L 91 (N 400, dx~25 km) 1 deterministic run +8. 0 h – Tl 399 L 62 (N 200, dx~50 km) 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 n ECMWF 1 deg fields at NCEP NHC n +7. 0 h – 120 -h 1 deg DET solutions available n NHC n n forecast process starts +6. 5 need CON by + 6. 5 h JTWC n forecast process starts +7. 0 need CON by + 7. 5 h n “on time” model trackers ≤ 6. 5 h n “late” model trackers > 6. 5 h M. Fiorino : : 61 st IHC 20070307 New Orleans, LA

Summary of ECMWF timing and prospects for 2007 NHEM season… ECMWF trackers “late” NCEP/NHC tracker of ECMWF 1 deg semi “on-time” ECMWF working to decouple TC trackers from the EPS run, may be “on time” for 2007 M. Fiorino : : 61 st IHC 20070307 New Orleans, LA

Impact on CON… The Goerss Laws of CON_ or the conditions when medium-range forecast error of CON_> models 1) models have similar skill – applies in both directions… 2) error tend to be decorrelated M. Fiorino : : IHC 61 st NOLA 20070307

CONM – LANT 2006 ontime v late v all (CONM) 72 h ecmo 06 > ecmo 12 > conm >> conu contributes to CON, but not always … sampling problem late taus: model >> peers, CON < best model early taus: model << peers, CON degraded M. Fiorino : : 61 st IHC 20070307 New Orleans, LA

CONM – EPAC 2006 ontime v late v all (CONM) ecmo 06 & ecmo 12 ~ other models but contributes because of error decorrelation model ~ peers, CON > best model error compensation M. Fiorino : : 61 st IHC 20070307 New Orleans, LA

CONM – WPAC 2006 ontime v late v all (CONM) big impact at d+5 model ~ peers, big contribution to CON at all taus M. Fiorino : : 61 st IHC 20070307 New Orleans, LA

Summary and some Speculation… n ECMWF makes positive contribution to CON > current baseline CON at the medium-range n n Performance varies by basin synoptic pattern subtropical ridge/midlat baroclinic activity n n n exception was the LANT because it was much better than other members (Goerss CON rule 1) 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 … M. Fiorino : : 61 st IHC 20070307 New Orleans, LA

Feb 2005 Commander Fiorino, what’s your forecast for my 2005 WESTPAC season? COMPACFLT Meteorologist It won’t be like 2004 Captain… M. Fiorino : : IHC 61 st NOLA 20070307

NHEM TC activity anomalies 2003 -2006 n n n M. Fiorino : : 61 st IHC 20070307 New Orleans, LA 2006 ∟ 2005 WPAC year-toyear 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

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 … M. Fiorino : : IHC 61 st NOLA 20070307