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WGNE-26

WGNE-26. 18-22 October 2010, Tokyo. Projections of the Changes in Tropical Cyclone Frequency and Intensity due to Global Warming using High-resolution AGCMs. Masato Sugi Japan Agency for Marine-Earth Science and Technology Yokohama, Japan msugi@jamstec.go.jp.

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WGNE-26

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  1. WGNE-26 18-22October 2010, Tokyo Projections of the Changes in Tropical Cyclone Frequency and Intensity due to Global Warming using High-resolution AGCMs Masato Sugi Japan Agency for Marine-Earth Science and Technology Yokohama, Japan msugi@jamstec.go.jp

  2. Progress in Projections of TC Frequency and Intensity Changes due to Global Warming I. 1992-2001 T106 (~120km) CRAY-YMP 1 GFLOPS II. 2002-2011 TL959 (~20km) Earth Simulator 40 TFLOPS III. 2012- ~3.5km K-Computer 10 PFLOPS

  3. I. 1992-2001 T106 (~120km) CRAY-YMP 1 GFLOPS Main Results ◆ Significant reduction in the global TC frequency. ◆ Mechanism of the global TC frequency change.

  4. Present and Future TC Tracks Sugi et al. 1997, WGNE Report Sugi et al. 2002, JMSJ Reduction of Global TC Counts by 30%

  5. TC Frequency Changes ( Future/Present % ) ◆ Significant reduction in the global TC frequency. ◆ Discrepancy in the regional TC frequency changes.

  6. Mechanism of the Global TC Frequency Change ◆ Global TC frequency change Large moisture increase Little precipitation increase ⇒ Weakening of tropical circulation ⇒ Reduction in global TC frequency

  7. Mechanism of the global TC frequency reduction Sugi et al. (2002) JMSJ, Sugi and Yoshimura (2004) J.Climate significant increase in stability significant increase in moisture warming little increase in precipitation CO2 increase little increase in radiative cooling decrease in TC frequency decrease in upward mass flux

  8. Weakening of Tropical Circulation (decrease in upward mass flux) Sugi et al. 2002, JMSJ M: massflux S: stability q: humidity Q: heating P: precipitation

  9. Weakening of Upward Velocity in CMIP3 Models Vecchi and Soden, 2007 J. Clim. Held and Soden 2006, J. Clim.

  10. Changes inTC frequency when only SST or only CO2 is increased SST: increase Precipitation: increase Stability: increase TC frequency: no change CO2: increase Precipitation: decrease Stability: no change TC frequency: decrease Yoshimura and Sugi 2005, SOLA

  11. Two effects of CO2 increase on TC frequency Yoshimura and Sugi 2005, SOLA Sugi and Yoshimura (2004) J.Climate precipitation increase greenhouse effect SST increase atmospheric moisture increase little change in TC frequency stability increase CO2 increase overlap effect H2O and CO2 absorption bands atmospheric radiative cooling decrease reduction in TC frequency precipitation decrease

  12. II. 2002-2011 TL959 (~20km) Earth Simulator 40 TFLOPS ◆ 2002-2006: KYOSEI Project ◆ 2007-2011: KAKUSHIN Program Main Results ◆ Significant reduction in the global TC frequency. ◆ Increase in frequency of intense TCs. ◆ Mechanism of regional TC frequency change.

  13. KYOSEI Project TC Tracks Oouchi et al. 2006, JMSJ Present Future

  14. KYOSEI Project TC intensity distribution Oouchi et al.2006 20km mesh

  15. TC intensity distribution KAKUSHIN Program OLD : AS scheme NEW: Yoshimura scheme OBS (Best Track) 25year (1979-2003 ) 20km Model Present 25year (1979-2003 ) 20km Model Future 25year (2075-2099 )

  16. Storm-Days Green: Obs.（1979-2003） Blue：20km Present（1979−2003） Red：20km Future（2075−2099）

  17. All TCs Numbers : Total Storm-days in Each Ocean Basin per 25Years

  18. Category 1（33.0 ≤ WS<43.0 m/s)

  19. Category 2（43.0 ≤ WS<49.4 m/s)

  20. Category 3（49.4 ≤ WS<58.6 m/s)

  21. Category 4（58.6 ≤ WS < 69.4 m/s)

  22. Category 5（69.4m/s ≤ WS)

  23. Mechanism of the Regional TC Frequency Change ◆ Regional TC frequency change SST distribution change ⇒ Redistribution of tropical convection ⇒ Redistribution of regional TC frequency

  24. Knutson et al. 2010 Global/Regional TC frequency changes

  25. Regional TC Frequency Change and SST

  26. Relative SST Change Precipitation Change TC Frequency Change CMIP3 MRI NWP (-) NA (+) MIROC NWP (+) CSIRO NA (-)

  27. III. 2012- ~3.5km K-Computer 10 PFLOPS Future Works ◆ Key to the more reliable projection of TC frequency and intensity changes is the cumulus convection. ◆ Two ways to improve cumulus convections: 1. Improve parameterization. 2. Global Cloud Resolving Model.

  28. 4 day forecast of T0422 from 2004.10.4 00UTC OLD (AS scheme) NEW (Yoshimura scheme) TL319L40 (60km) 995 997 TL959L60 (20km) 983 993

  29. Ensemble experiments to estimate uncertainty in a projection of regional climate changes Model ensemble SST ensemble Different model response to SST Different relative SST distribution Tropical convective activity Tropical circulation Global circulation Regional Climate Tropical cyclone activity

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