1. JP1.18 Physical processes associated with surface wind field uncertainty in Hurricanes Katrina and Rita (2005): Use of present and future observational tools Peter G. Black NOAA/AOML/HRD, Miami, FL (present affiliation: SAIC at NRL, Monterey, CA), and E. W. Uhlhorn, J. F. Gamache, R. D. Knabb, J. Carswell, P. S. Chang, S. Lorsolo, R. E. Hood, L. Jones, I. Popstefanija and A. S. Goldstein Photo: Randy Bynon, AFRC/ 53 rd Weather Reconnaissance Squadron, Keesler AFB, MS: Eye of Hurricane Felix (2007) at night from WC-130J reconnaissance aircraft. Background Three new airborne observing technologies are synthesized to obtain the time evolution of the structure and intensity of Hurricanes Katrina and Rita as they approached landfall in the northern Gulf of Mexico 1. GPS dropsondes 2. Stepped Frequency Microwave Radiometer- SFMR 3. TAil Doppler radar The Integrated Wind and Rain Airborne Profiler (IWRAP), flown in selected hurricanes from 2002-2006, and the Hurricane Imaging RADiometer (HIRAD), the next-generation scanning SFMR, are scheduled for operational implementation in 2009 on the NOAA P3. These observing systems reduce uncertainty in surface horizontal wind field and vertical boundary layer structure. Discussion Lower-left: Flight level and SFMR surface winds along an east-west transect through Katrina on 28 Aug, near the time of peak intensity, and (upper-right) on 29 Aug, just prior to landfall. Middle-right is flight track on the 29 th and lower-right is the legend. Scanning patterns for NOAA WP-3D remote sensing instrumentation. Lower-left: Flight tracks of AFRC WC-130J at 700 mb level. Upper-left: HWIND analysis of 700 mb flight level data reduced to the surface. Lower-right: SFMR WP-3D flight track. Upper-right: SFMR HWIND analysis for same time period. Lower-left: Composite radar reflectivity from WP-3D Lower Fuselage radar for 29 Aug with dashed line indicating flight track. Lower-right: TAil Doppler radar wind speed at 1 km. Upper- right: Vertical profile of horizontal wind speed. Upper panel: SW to NE vertical profile of TA Doppler horizontal wind speed on 28 Aug. Lower panel: Same but for 29 Aug Upper-right: 700 mb flight level and SFMR wind speed for 21 Sept with gradient wind and dropsonde surface winds having the same symbols as for Katrina. Middle-left and lower- right: Same except for 22 and 23 Sept, respectively. Upper-left: Radial/ vertical Doppler wind profile for 21 Sept. Upper-right: Vertical profile of horizontal Doppler wind speed. Lower-left: Same as upper-left, but for 23 Sept. Lower- right: Same as upper-right, but for 23 Sept. Left: Hurricane Isabel GOES VIS image, with inset showing horizontal sonde trajectory for a six-sonde sequence in the north eyewall. Right: Vertical sonde trajectory compared to IWRAP vertical scan location. HIRad scan geometry and sample swath coverage from GIV altitudes for Hurricane Floyd wind field OSSE using MM5 model. The observations from both storms in the study show a remarkable transformation from a compact CAT4/5 storm offshore to a considerably weaker storm during the landfall process. Transformation is documented from sharply-peaked wind profiles with radius of maximum winds near 20 km and peak surface winds near 70 m/s to broad wind maxima with radius of maximum wind of 60-70 km and peak winds of 45 m/s- but spread over a 120 km wide swath to the right of the center. This change resulted in conditions maximizing the devastating storm surge in Katrina's case and in maximizing damage to offshore structures in Rita’s case. Further Research The use of IWRAP for continuous vertical profiling of boundary layer winds and HIRad for expanding the swath of surface wind observations beyond the aircraft track, illustrate new tools that will become available over the next few years to reduce uncertainty in surface winds that impact coastal populations and play a pivotal role in estimating destructive storm surge and wave run-up near landfall. Impacts of the analysis of these data in real time as well as post event synthesis of the surface wind field proved significant for Katrina and Rita, and likely will continue to be significant in the future as new SFMR systems become available operationally on the fleet of ten WC-130J's operated by the 53rd Weather Reconnaissance Squadron and IWRAP and HIRad systems become operational on the NOAA WP-3D aircraft. IWRAP and dropsonde vertical profile comparison for wind speed (left) and wind direction (right).