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Dynamic Hurricane Season Prediction Experiment with the NCEP CFS CGCM Lindsey Long and Jae Schemm Climate Prediction Center / Wyle IS NOAA/NWS/NCEP October 27, 2009 The 34th Climate Diagnostics and Prediction Workshop, Monterey, CA
Outline • Description of the CFS Experiments • Datasets Used • Analysis of storm activity statistics • Focus on the Atlantic and Western North Pacific basins • Statistics and performance evaluation • Future plan
CFS T382 Hurricane Season Experiments • One of the FY07/08 CTB internal projects • Model Components: • AGCM: 2007 operational NCEP GFS in T382/L64 resolution • LSM: Noah LSM • OGCM: GFDL MOM3 • All runs initialized with NCEP/DOE R2 and NCEP GODAS. • 00Z Initial Conditions from April 19-23 • Runs through December 1st • Tropical cyclone detection and tracking method based on Camargo and Zebiak (2002) • Vorticity max, pressure min, wind max, warm-core system
Datasets • CFS Hindcasts at T382 (~33km) • 5-Member Ensemble • April 19th-23rd Initial Conditions • Output every 6 hours • 1981-2008, 28 years • Appropriate ICs for CPC Operational Hurricane Season Outlook • Observations from the HURDAT and JTWC Best Track Dataset • Tropical depressions and subtropical storms are not included in storm counts.
Atlantic Eastern North Pacific Western North Pacific North Indian Examples of Storm Tracks for 4 NH Basins
Composite of 20 Atlantic Storms With SLP < 990hPa Max winds, 27 m/s Min Pressure, 984 hPa
Atlantic Basin Obs Clim – 11.4 CFS Clim – 10.9 Atlantic Tropical Storms May-Nov, 1981-2008, T382
Eastern Pacific Obs Clim – 16.3 CFS Clim – 13.0 Eastern Pacific Tropical Storms May-Nov, 1981-2008, T382
Western Pacific Obs Clim – 24.2 CFS Clim – 18.1 Western Pacific Tropical Storms May-Nov, 1981-2008, T382
JJA Nino 3.4 SST Index Red= Statistically Significant at 0.95
JJA Atlantic MDR SST Index Red= Statistically Significant at 0.95
JJA Atlantic MDR Shear Index Red= Statistically Significant at 0.95
Anomalous Number of TC: Atlantic Basin Red= Statistically Significant at 0.95
Atlantic Basin ACE Index % of Normal Red= Statistically Significant at 0.95
Anomalous Number of TC: Western N. Pacific Red= Statistically Significant at 0.95
WNP Basin ACE Index % of Normal Red= Statistically Significant at 0.95
CFS April 2009 ForecastAtlantic BasinStorm Count and ACE Index ATL – Below Average Year Predicted CFS predicted 7.5 storms versus a 10.9 storm climatology. With an ACE Index of only 75% of Normal
Courtesy of Unisys 8 Named Storms for 2009: 6 TSs and 2 Hurricanes 28-Yr Climatology = 11.6 Storms
CFS April 2009 ForecastWestern N. Pacific BasinStorm Count and ACE Index WNP – Above Average Year Predicted CFS predicted 21.5 storms versus a 18.1 storm climatology. With an ACE Index of 144% of Normal
As of Oct 22, Courtesy of Unisys 24 Named Storms for 2009: 12 TSs and 8 Typhoons, 4 Super Typhoons 28-Yr Climatology = 27.3 Storms
Summary • CFS in T382 resolution exhibits robust climatological seasonal cycle of tropical cyclones over three NH basins. • Warming trend and intensification of hurricane activity in the Atlantic basin captured in the CFS hindcasts. • Fair level of skill in predicting interannual variability of seasonal storm activities for the Atlantic and West. N. Pacific basins. • Provided input for the 2009 CPC Hurricane Season Outlook with real time prediction runs. Plans for an operational implementation in 2010.