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An attempt to homogeneously describe 60 years statistics of TC activity in E Asia, 1948-2007

This study aims to provide a comprehensive analysis of tropical cyclone activity in East Asia over a 60-year period. The research utilizes regional atmospheric models and global reanalysis data to simulate and analyze typhoons in the region. The results show variability in TC numbers and intensity, with no overall trend in numbers but slight upward trends in minimum pressure and maximum wind since the 1990s. Further validation and better data are needed for improved accuracy. Workshop on this topic will be held in March 2009 in Taipei or Tainan, Taiwan.

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An attempt to homogeneously describe 60 years statistics of TC activity in E Asia, 1948-2007

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

  2. Applications: past and future marine weather in N Europe downscaling cascade for constructing variable regional and local marine weather statistics Simulation with barotropicmodel of North Sea Globale development(NCEP) Dynamical DownscalingREMO or CLM Cooperation with a variety of governmental agencies and with a number of private companies

  3. Baroclinic storms in N Europe • Problem for synoptic systems solvedby CoastDat@GKSS in N Europe, using RCM spectrally nudged to NCEP • retrospective analysis 1958-2005 • good skill with respect to statistics, but not all details are recovered. Weisse, R., H. von Storch and F. Feser, 2005: Northeast Atlantic and North Sea storminess as simulated by a regional climate model 1958-2001 and comparison with observations. J. Climate 18, 465-479

  4. 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

  5. A case study: Simulating tropical storm Winnie (August 1997) with regional atmospheric model CLM

  6. 12 TCs in Season 2004 only 10 were found in CLM simulation Following Zhang et al., 2007. Meteor. Atmos. Phys.

  7. Complete simulation of 1948-2007using CLM with 0.5º grid resolutionand NCEP/NCAR reanalysis Spectral nudging of scales larges than about 800 km. Results are new; thus may be subject to future revisions!

  8. 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.

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  10. 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.

  11. Next workshop: 11+12 March 2009, Taipei or Tainan, Taiwan

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