1. 12. September 2008 Jährliches Treffen SWA - GKSS Page 1 An attempt to homogeneously describe 60 years statistics of TC activity in E Asia, 1948-2007 Hans von Storch and Frauke Feser 1 Institute for Coastal Research, GKSS Research Center, Germany 2 clisap-Klimacampus, University of Hamburg, Germany

2. 12. September 2008 Jährliches Treffen SWA - GKSS Page 2 Applications: past and future marine weather in N Europe Globale development (NCEP) Dynamical Downscaling REMO or CLM Simulation with barotropic model of North Sea Cooperation with a variety of governmental agencies and with a number of private companies downscaling cascade for constructing variable regional and local marine weather statistics

3. 12. September 2008 Jährliches Treffen SWA - GKSS Page 3 Downscaling SE Asian marine weather We have implemented the dynamical downscaling approach for SE Asian marine weather. The key question is – will we master the description of typhoons? Done: Case studies and seasons – formation of typhoons induced by large scale dynamics and NOT by initial values. Presently under examination: Continuous 6-decade simulations constrained by NCEP global re-analyses. Feser, F.,and H. von Storch, 2008: Regional modelling of the western Pacific typhoon season 2004, Meteor. Z. 17 (3), 1-10. DOI: 10.1127/0941- 2948/2008/0282 Feser, F., and H. von Storch, 2008: A dynamical downscaling case study for typhoons in SE Asia using a regional climate model. Mon. Wea. Rev. 136, 1806-1815

4. 12. September 2008 Jährliches Treffen SWA - GKSS Page 4 A case study: Simulating tropical storm Winnie (August 1997) with a regional a climate model -Sensitivity to spectral nudging -Sensitivity to horizontal resolution with regional atmospheric model CLM; initiated at or close to 1. August 1997 (about 10 days prior to formation)

5. 12. September 2008 Jährliches Treffen SWA - GKSS Page 5 Core pressure development

6. 12. September 2008 Jährliches Treffen SWA - GKSS Page 6 12 TCs in Season 2004 only 10 were found in CLM simulation Following Zhang et al., 2007. Meteor. Atmos. Phys.

7. 12. September 2008 Jährliches Treffen SWA - GKSS Page 7

8. 12. September 2008 Jährliches Treffen SWA - GKSS Page 8 Complete simulation of 1948-2007 using CLM with 0.5º grid resolution and NCEP/NCAR reanalysis Spectral nudging of scales larges than about 800 km. Results are new; thus may be subject to future revisions!

9. 12. September 2008 Jährliches Treffen SWA - GKSS Page 9 Criteria have subjectively been selected so that the mean number of TCs detected in the simulation is about equal to the mean number given in the best track data.

10. 12. September 2008 Jährliches Treffen SWA - GKSS Page 10

11. 12. September 2008 Jährliches Treffen SWA - GKSS Page 11 ??????????????????????

12. 12. September 2008 Jährliches Treffen SWA - GKSS Page 12 Beide Datensätze: JMA Best Track und NCEP Re-Analyse sind inhomogen! JMA best track NCEP/NCAR Southern Hemisphere Northern Hemisphere

13. 12. September 2008 Jährliches Treffen SWA - GKSS Page 13 Conclusions (Some) typhoons can be described by regional atmospheric models run in the climate mode. But, downscaled (simulated) TCs are too weak in terms of core pressure, maximum pressure fall and maximum sustained wind. We need better data for validation. Preliminary results concerning change -Strong year-to-year variability -Little decadal variability -No overall trend in numbers -Slight upward trends in minimum pressure and max wind since 1990s.