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The 63 rd Interdepartmental Hurricane Conference St Petersburg, Florida, March 2-5, 2009

Sensitivity of the HWRF model prediction for Hurricane Ophelia (2005) to the choice of the cloud and precipitation scheme Yuqing Wang and Qingqing Li International Pacific Research center University of Hawaii at Manoa , Honolulu, HI 96822.

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The 63 rd Interdepartmental Hurricane Conference St Petersburg, Florida, March 2-5, 2009

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  1. Sensitivity of the HWRF model prediction for Hurricane Ophelia (2005) to the choice of the cloud and precipitation schemeYuqing Wang and Qingqing LiInternational Pacific Research centerUniversity of Hawaii at Manoa, Honolulu, HI 96822 The 63rd Interdepartmental Hurricane Conference St Petersburg, Florida, March 2-5, 2009 Acknowledgments: Naomi Surgi, Steve Lord, HWRF team as NCEP/EMC

  2. Some systematic biases of HWRF • The storm size is generally too large (increase with time); • Large storms are too strong while small storms are too weak; • Storms are too energetic and hard to dissipate; • It performs best for storms in weak shear environment; • Problems in mid-upper level structure for storms in vertical shear environment.

  3. Liu et al. 2008, originally from Biju Thomas

  4. Objectives • To identify the model physics that are critical to the structure and intensity changes in the HWRF model; • To improve the representation of those model physics to achieve improved prediction of hurricane structure and intensity changes by HWRF model.

  5. Working Hypothesis • 3D distribution of diabatic heating due to phase changes is the key to both the structure and intensity of hurricanes; • The vertical heating distribution in in eyewall determined the rate of intensity change, while horizontal heating distribution determines the storm size change; • Realistic representation of 3D diabatic heating due to phase changes is the fundamental to any model to achieve improved prediction for hurricane structure and intensity!

  6. How sensitive the simulated hurricane size is to heating in the outer spiral rainbands of the hurricane in the nonhydrostatic hurricane model TCM4

  7. Cloud top brightness temperatures (in Celsius) from satellite observation for Hurricane Ophelia (2005) at 18 UTC 12 September 2005.

  8. Numerical model settings and experimental design

  9. The model domain used in all experiments. The outer domain D1 is 0.25o resolution and the inner domain D2 is 0.08333o resolution

  10. Observed (black) and simulated (red) tracks of Hurricane Ophelia (2005) in experiments (a) NKF, (b) KF, (c) NBM, and (d) BM, respectively, with marks at 6-h intervals.

  11. 96-h evolution in the maximum 10-m wind speed (dashed in m s-1) and the central sea level pressure (solid in hPa) of Hurricane Ophelia (2005) from observation (red) and simulations (blue); (a) NKF, (b) KF, (c) NBM, and (d) BM.

  12. NKF NBM KF BM Cloud top brightness temperatures (Celsius) simulated in experiments (a) NKF, (b) KF, (c) NBM, and (d) BM at 18 UTC 12 September 2005.

  13. CAPE simulated in experiments (a) NKF, (b) KF, (c) NBM, and (d) BM at 18 UTC 12 September 2005.

  14. Proposed Work • Fast and slow cloud microphysics processes should not be equally weighted and the sedimentation of cloud ice should not be neglected. • Both would make the cloud microphysics scheme less time-step/resolution dependent and producing more realistic 3D distribution of diabatic heating due to phase changes. • The growth and nucleation of liquid and ice clouds depends strongly on grid-scale vertical motion and subgrid-scale turbulence, critical to horizontal extent of diabatic heating. • To take into account the subgrid-scale super-saturation in both stratiform and convective parameterization schemes is critical to realistic simulation of cloud structure and heating due to phase changes.

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