1. Dynamic Hurricane Season Prediction Experiment with the NCEP CFS Jae-Kyung E. Schemm January 21, 2009 COLA CTB Seminar Acknowledgements: Lindsey Long Suru Saha Shrinivas Moorthi

2. Outline Description of the CFS experiment Datasets Used IRI Detection and Tracking Method Analysis of storm activity statistics Evaluation of CFS performance on environmental variables related to storm activity A look at CFS-based predictions for 2008 season Summary and future plan

3. CFS T382 hurricane season experiments 1.One of the FY07/08 CTB internal projects 2.AGCM - 2007 operational NCEP GFS in T382/L64 resolution LSM - Noah LSM OGCM - GFDL MOM3 3. All runs initialized with NCEP/DOE R2 and NCEP GODAS. Initial conditions at 0Z, Apr. 19, 20, 21 and May 15(FY07) for 1981-2007. Forecasts extended to December 1. 4.For May 15 cases, runs in T62 and T126 resolutions also performed.

4. Datasets  CFS hindcasts at T382 May 15 th Initial Condition Output at every 3 hours 1981-2007, 27 years April 19 th, 20 th and 21 st Initial Condition Output at every 6 hours 1981-2008, 28 years More 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.

5. Tropical Cyclone Detection Method Based on method devised by Camargo and Zebiak (2002) at IRI Detection algorithm uses basin-dependent threshold criteria for three variables Vorticity,  thresh   thresh = 2   10-m Wind Speed,  thresh   thresh =  gl +     gl = wind speed averaged over all global basins Vertically integrated temp anomaly, T thresh T thresh =  T /2 Calculated using only warm-core systems

6. Table of Basin Thresholds ATLENPWNPNI  * 10 -5 4.23.94.14.0  3.53.43.73.4 T 0.310.320.300.28 CFS T382 thresholds for vorticity, surface wind speed, and vertically integrated temperature anomaly for each ocean basin.

7. 1.850-hPa relative vorticity >  thresh 2.Maximum 10-m wind speed in a 7x7 box >  thresh 3.SLP is the minimum in the centered 7x7 box 4.Temp anomaly averaged over the 7x7 box and three pressure levels (300, 500, & 700 mb) > T thresh 5. Temperature anomaly averaged over the 7x7 box is positive at all levels (300, 500, & 700 mb) * 6.Temperature anomaly averaged over the 7x7 box at 300mb > 850mb * 7.Wind speed averaged over the 7x7 box at 850mb > 300mb 8.The storm must last for at least 6 hours. * Criteria 5 & 6 define a warm core system. Eight conditions must be met for a point to be considered a tropical cyclone

8. Storm Tracking Once a point is designated as a tropical cyclone, the cyclone is tracked forward and backward in time to create a full storm track. The maximum vorticity in a 5x5 grid around the cyclone is found and a new 3x3 box is formed around it. At the next time step, if the maximum vorticity in this new box is greater than 3.5 x 10 -5 s -1, the procedure is repeated. This point has become part of the storm track. If two storm tracks are the same, they are considered the same cyclone and counted as one.

9. Four NH Ocean Basins

10. Western North PacificNorth Indian AtlanticEastern North Pacific Examples of Storm Tracks for 4 NH Basins

11. Atlantic Basin Atlantic Tropical Storms

12. Eastern Pacific Basin Eastern Pacific Tropical Storms

13. Western Pacific Basin Western Pacific Tropical Storms

14. Atlantic Basin Correlations Anomalies of Atlantic Storms N=27 N=13 N=13 CorrelationsTotal81-9394-06 IC=04190.44-0.100.14 IC=04200.33 0.36 IC=04210.350.230.24 April Ensm0.490.180.33 IC=05150.350.180.40 Red = Statistically Significant at 0.95

15. N=27 N=13 N=13 ENP Correlations Anomalies of Eastern North Pacific Storms CorrelationsTotal81-9394-06 IC=0419-0.040.14-0.14 IC=0420-0.03-0.13-0.06 IC=0421-0.02-0.180.26 April Ensm-0.07-0.15-0.08 IC=05150.12-0.01-0.02 Red = Statistically Significant at 0.95

16. N=27 N=13 N=13 WNP Correlations Red = Statistically Significant at 0.95 Anomalies of Western North Pacific Storms CorrelationsTotal81-9394-06 IC=04190.400.300.61 IC=04200.470.190.69 IC=04210.010.270.01 April Ensm0.370.250.62 IC=05150.37-0.020.52

17. N=27 N=13 N=13 CorrelationsTotal81-9394-06 IC=04190.470.050.23 IC=04200.580.700.15 IC=04210.280.000.48 April Ensm0.520.230.38 IC=05150.660.610.69 Atlantic Basin ACE Index Red = Statistically Significant at 0.95 % of Normal

18. ATL Detrended Correlations N=27 N=13 N=13 0.42-0.130.22IC=0515 0.340.160.35April Ensm 0.240.380.25IC=0421 0.400.320.34IC=0420 0.010.190.24IC=0419 94-0681-93TotalCorrelations Red = Statistically Significant at 0.95

19. ATL Detrended, Step Function Correlations N=27 N=13 N=13 0.490.110.35IC=0515 0.300.220.49April Ensm 0.100.250.29IC=0421 0.450.360.38IC=0420 0.150.230.46IC=0419 94-0681-93TotalCorrelations Red = Statistically Significant at 0.95 Climatology used for detrending is broken into two 13-year periods, the inactive period of 1981-1993 and the active period 1994-2006

20. Evaluation of SST and Wind Shear prediction for storm season

21. JJA Nino 3.4 SST Index T382COR IC=04190.722 IC=04200.667 IC=04210.677 April Ensm0.707 IC=05150.872 Red = Statistically Significant at 0.95

22. ASO Nino 3.4 SST Index T382COR IC=04190.690 IC=04200.603 IC=04210.626 April Ensm0.676 IC=05150.878 Red = Statistically Significant at 0.95

23. JJA Atlantic MDR SST Index T382COR IC=04190.629 IC=04200.635 IC=04210.726 April Ensm0.691 IC=05150.781 Red = Statistically Significant at 0.95

24. ASO Atlantic MDR SST Index T382COR IC=04190.643 IC=04200.655 IC=04210.771 April Ensm0.744 IC=05150.742 Red = Statistically Significant at 0.95

25. JJA Atlantic MDR Shear Index T382COR IC=04190.435 IC=04200.539 IC=04210.657 April Ensm0.603 IC=05150.615 Red = Statistically Significant at 0.95 Wind Shear: U 200 – U 850

26. ASO Atlantic MDR Shear Index T382COR IC=04190.466 IC=04200.394 IC=04210.474 Apr Ensm0.502 IC=05150.481 Red = Statistically Significant at 0.95 Wind Shear: U 200 – U 850

41. TNA Non-Local Index, Jun-Nov T382TNA IC=04190.364 IC=04200.542 IC=04210.685 April Ensm0.626 Red = Statistically Significant at 0.95 [60W-30W; 5N-20N] - [0-360, 0-15N] SSTA T382 ACE Obs/Fcst IC=04190.467/0.632 IC=04200.537/0.373 IC=04210.757/0.449 April Ensm0.662/0.648 Obs0.699

42. 2008 Atlantic Season Summary Obs NOAA Outlook Outlook Update CFS-Stat May CFS-Stat Update Named Storm 1612-1614-189-1613-16 Hurricane 86-97-105-97-10 Major Hurricane 52-53-62-43-5

43. Atlantic Basin Prediction for 2008 Two additional runs were made using July 15 th and 16 th initial conditions for 2008 only Used as a trial run for the CPC Hurricane Outlook Update

44. 13.330.67132.333.671.331ENSM 16128410716 93420715 16 1 4431Obs 11133310422 152423310421 1411235110419 TotalNovOctSepAugJulJunMay2008 Atlantic Basin CFS 2008 Monthly Storm Count 3

45. (Courtesy of Unisys) Large number of storms over the Gulf of Mexico this year 2008 Atlantic Storm Tracks

46. Resemble Bertha and Cristobal

47. . Summary  CFS in T382 resolution exhibits robust climatological seasonal cycle of tropical cyclone over four 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 based on the limited number of forecast runs.  Model SST and wind shear bias explain part of less number of TCs in Atlantic and EN Pac. basins, in particular over the Gulf of Mexico.  Continue to increase number of ensemble members for better climatology and storm statistics. Hope to provide input for 2009 Hurricane Season Outlook with real time prediction runs.  Multi-model ensemble approach for dynamical hurricane season prediction is being explored.