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Technique:

Surface Fluxes at High Wind Speeds Deduced from Dense Dropwindsonde Deployments in Hurricanes Fabian and Isabel Kerry Emanuel Program in Atmospheres, Oceans, and Climate MIT. Technique:.

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  1. Surface Fluxes at High Wind Speeds Deduced from Dense Dropwindsonde Deployments in Hurricanes Fabian and IsabelKerry EmanuelProgram in Atmospheres, Oceans, and ClimateMIT

  2. Technique: Deploy very dense array of GPS dropwindsondes across eyewall to measure radial, azimuthal and vertical flow and thermodynamic properties with enough resolution to deduce surface fluxes from budget residuals

  3. Steady State:

  4. Angular Momentum and Energy: Note: Turbulent flux from top of PBL not small

  5. Compositing Data • GPS dropsonde and flight level data • Radial symmetry of storms necessary • Transformation to radial and tangential winds very sensitive to location of storm center

  6. Storm Centering Considerations • Maximize conservation of M above boundary layer • Maximize agreement between tangential and gradient wind above PBL • Minimize sensitivity of flux calculations to width and depth of box

  7. Some preliminary results from Hurricane Isabel

  8. Fluxes from dropsonde data as a function of box depth run# xc yc rmin rmax zmax vbar vgrad stress flux cd ck ---- -- -- ---- ---- ---- ---- ----- ------ ---- -- -- run1 0.120 0.044 22.0 34.0 2000.0 71.4 62.9 9.94 1818 0.00235 0.00340 run1 0.120 0.044 22.0 34.0 1800.0 71.4 63.7 10.94 1301 0.00255 0.00238 run1 0.120 0.044 22.0 34.0 1600.0 71.4 63.8 12.36 1615 0.00282 0.00290 run1 0.120 0.044 22.0 34.0 1400.0 71.4 64.1 10.46 1880 0.00234 0.00332 run1 0.120 0.044 22.0 34.0 1200.0 71.4 64.6 15.03 2489 0.00332 0.00434 run1 0.120 0.044 22.0 34.0 1000.0 71.4 64.5 15.40 1511 0.00338 0.00265 run1 0.120 0.044 22.0 34.0 800.0 71.4 64.7 15.73 1903 0.00334 0.00342 run1 0.120 0.044 22.0 34.0 600.0 71.4 64.6 12.64 2731 0.00259 0.00510 run1 0.120 0.044 22.0 34.0 400.0 71.4 64.2 9.89 1552 0.00195 0.00300 run1 0.120 0.044 22.0 34.0 200.0 71.4 65.2 4.95 1209 0.00096 0.00255

  9. Using aircraft-derived fluxes at top and varying lateral dimensions of box run# xc yc rmin rmax zmax vbar vgrad stress flux cd ck ---- -- -- ---- ---- ---- ---- ----- ------ ---- -- -- run1 0.120 0.044 22.0 34.0 2154.5 71.4 63.2 10.40 1209 0.00249 0.00225 run1 0.120 0.044 23.0 34.0 2154.5 71.8 63.0 13.02 2008 0.00312 0.00376 run1 0.120 0.044 24.0 34.0 2154.5 71.7 62.7 14.10 2627 0.00339 0.00493 run1 0.120 0.044 25.0 34.0 2154.5 71.9 63.1 15.84 3358 0.00376 0.00626 run1 0.120 0.044 22.0 33.0 2154.5 71.6 65.8 9.93 -179 0.00221 -0.00032 run1 0.120 0.044 22.0 35.0 2154.5 71.5 59.6 12.20 1330 0.00318 0.00260

  10. Estimates of exchange coefficients from Run 1:

  11. Summary • Isabel and Fabian are very nearly ideal storms for budget analyses • Dropsonde deployment and data nearly flawless • Major issue in budget analysis is storm centering and loss of drop data at lowest levels • Need higher resolution aircraft data • Working on other Isabel runs and on composites involving all Isabel runs

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