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Miscellaneous HiFi Slides

Miscellaneous HiFi Slides. from Lukas overview talk. What factors presently limit intensity forecast skill?. Ocean heat distribution, especially eddies Variable efficiency of ocean heat extraction Interaction of storm with changing atmospheric environment

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Miscellaneous HiFi Slides

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  1. Miscellaneous HiFi Slides

  2. from Lukas overview talk

  3. What factors presently limit intensity forecast skill? • Ocean heat distribution, especially eddies • Variable efficiency of ocean heat extraction • Interaction of storm with changing atmospheric environment • asymmetries, eyewall dynamics, meso-vortices, etc. • Inability of current numerical forecast models to simultaneously include all important processes and their interactions within storms • Initialization Bao et al. (2000) infinite heat capacity 48 hours

  4. Rapid intensification of Hurricane Opal after crossing warm core eddy Hong et al. (2000)

  5. Hurricane Frances – impact of coupling Blue- GFDL operational coupled model Red- GFDL uncoupled model

  6. Cd, with relationships and values from tropical cyclone budget studies Powell et al. (2003) Turbulent momentum exchange and wave field are tightly coupled But, spray stratification may also reduced Cd

  7. aircraft altitude = 253 m wind speed 46 ms-1 aircraft altitude = 450 m wind speed 55 ms-1 M. Powell, HRD/AOML/NOAA

  8. Schade and Emanuel (1999)

  9. Intensive study of Hurricane Dennis during August 1999, combining remote sensing, aircraft observations, and ocean mixed layer floats (D’Asaro, 2003) More hurricane process studies are needed with more comprehensive observations

  10. air with some spray droplets ρa spray and bubbles suspensionN2 >> 0 seawater with some bubbles ρo (After Emanuel, 2003) altered stratification affects turbulence production and wave field

  11. from Chris Fairall

  12. Feedback Sensitivity:Source Strength=0.3

  13. But:Simulations with New Cd and Ce/Ch Old Cd Ce/Ch New Cd Ce/Ch

  14. From Jim Price

  15. Upper ocean response to a hurricane CBLAST in situ data: EM-Apex by Tom Sanford and Doug Webb GOES SST imagery: EM-APEX 1633 • Goals: • Analyze these data for the processes that are of importance to • modeling the upper ocean response. • 2) Develop and provide an ocean model that is suitable for use in a coupled • hurricane/ocean modeling system.

  16. Upper ocean response to a hurricane EM-APEX 1633 Forced stage response during the hurricane passage: very strong wind stress generates near-inertial period currents, significant vertical mixing and SST cooling of several degrees C. emphasized here

  17. EM-Apex 1633, east and north velocity components

  18. sensitivity of model-computed SST cooling to the drag coefficient 1) There is a significant sensitivity of the SST cooling and ocean currents to Cd; the new high wind-speed saturated forms seem about right. 2) There is very little sensitivity of the SST cooling to Cq; advection and vertical mixing are a much bigger part of the upper ocean heat budget than is ocean-hurricane heat exchange.

  19. sensitivity of model-computed SST cooling to the drag coefficient Large and Pond 1981 Powell et al 2004 1) SST cooling and ocean currents are sensitive to Cd; the new high wind-speed saturated forms seem about right. 2) There is very little sensitivity of the SST cooling to Cq.

  20. 120 km to the left of the track hurricane Isabel 200 km to the south Fabian 110 km to the right of the track Solar heating post-Fabian rapidly covers over up SST variability. Wind-mixing associated with Isabel uncovers thermal variability.

  21. Miscellaneous sources

  22. from Chris Fairall Houston talk

  23. OCEAN Enters the Problem Through • Directly: SST, Waves, and Sea Spray • Indirectly: Entrainment and Bubbles • SST cooling in these images exhibits: • Significant horizontal structure, i) a marked rightward bias, ii) along-track • variability that is not correlated with intensity, and, • 2) A rapid relaxation back toward pre-storm SST, e-folding approx 10 days. day 250 EM-APEX 1634 1633 1636

  24. Droplet Effects Model Estimates • USATODAY.com Sea spray whips winds to hurricane strengthBy Michelle Lefort, USA TODAYPosted 7/31/2005 9:09 PM     Updated 7/31/2005 10:29 PM In a study out last week, researchers from the University of California, Berkeley, and a Russian colleague argue that sea spray kicked up by storms actually has a lubricating effect that helps accelerate wind. Suppress the sea spray, as ancient sailors tried to do with oil tossed on the water, and you may be able to affect the strength in the wind, the research suggests. The computer model by Berkeley mathematician Alexandre Chorin and his colleagues appears in the current Proceedings of the National Academy of Sciences. Chorin says that sea spray reduces turbulence — chaotic fluctuations in wind velocity and direction — like a comb through unruly hair.

  25. Sea Spray ProfilingEstimates Based on Fairall-Banner Model

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