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In a recent paper, Lee and Chen (2012, hereafter LC12) presented numerical simulations of symmetric and asymmetric hurricane boundary layer structures in a fully coupled atmosphere–wave–ocean model and used these simulations to compare aspects of the boundary layer structure against an analysis of observations. One of their main conclusions was that ‘‘the azimuthally averaged inflow layer tends to misrepresent the overall inflow structure in tropical cyclones, especially the asymmetric structure’’ (p. 3593). Another main conclusion was that the complicated asymmetric three-dimensional boundary layer structures (attributed by them to be) due in part to the air–sea and wind–wave coupling ‘‘make it difficult to parameterize the atmosphere–wave–ocean coupling effects without a fully coupled model’’ (p. 3593). After careful examination of their study, we have a number of questions regarding their methodology, their interpretations (including their interpretations of previous literature), and their conclusions. Specifically, we inquire about aspects of the methodology for defining the dynamical boundary layer depth, the selection of the boundary layer scheme, and we question the conclusions inferred. In addition to the foregoing concerns, inaccuracies in their literature review are noted and inconsistencies between their conclusions and reported results are identified.

At the time of the Deepwater Horizon oil rig explosion, the Loop Current (LC), a warm ocean current in the Gulf of Mexico (GoM), extended to 27.5 N just south of the rig. To measure the regional scale variability of the LC, oceanographic missions were flown on a NOAA WP-3D research aircraft to obtain ocean structural data during the spill and provide thermal structure profiles to ocean forecasters aiding in the oil spill disaster at 7 to 10 day intervals. The aircraft flew nine grid patterns over the eastern GoM between May and July 2010 deploying profilers to measure atmospheric and oceanic properties such as wind, humidity, temperature, salinity, and current. Ocean current profilers sampled as deep as 1500 m, conductivity, temperature, and depth profilers sampled to 1000 m, and bathythermographs sampled to either 350 or 800 m providing deep structural measurements. Profiler data were provided to modeling centers to predict possible trajectories of the oil and vector ships to regions of anomalous signals. In hindcast mode, assimilation of temperature profiles into the Hybrid Coordinate Ocean Model improved the fidelity of the simulations by reducing RMS errors by as much as 30% and decreasing model biases by half relative to the simulated thermal structure from models that assimilated only satellite data. The synoptic snapshots also provided insight into the evolving LC variability, captured the shedding of the warm core eddy Franklin, and measured the small-scale cyclones along the LC periphery.

This study analyzes the flight-level data collected by research aircraft that penetrated the eyewalls of category 5 Hurricane Hugo (1989) and category 4 Hurricane Allen (1980) between 1 km and the sea surface. Estimates of turbulent momentum flux, turbulent kinetic energy (TKE), and vertical eddy diffusivity are obtained before and during the eyewall penetrations. Spatial scales of turbulent eddies are determined through a spectral analysis. The turbulence parameters estimated for the eyewall penetration leg are found to be nearly an order of magnitude larger than those for the leg outside the eyewall at similar altitudes. In the low-level intense eyewall region, the horizontal length scale of the dominant turbulent eddies is found to be between 500 and 3000 m, and the corresponding vertical length scale is approximately 100 m. The results suggest also that it is unwise to include eyewall vorticity maxima (EVM) in the turbulence parameter estimation because the EVMs are likely to be quasi-two-dimensional vortex structures that are embedded within the three-dimensional turbulence on the inside edge of the eyewall. This study is a first attempt at estimating the characteristics of turbulent flow in the low-level troposphere of an intense eyewall using in situ aircraft observations. The authors believe that the results can offer useful guidance in numerical weather prediction efforts aimed at improving the forecast of hurricane intensity. Because of the small sample size analyzed in this study, further analyses of the turbulent characteristics in the high-wind region of hurricanes are imperative., Pub in Monthly Weather Review, v139 p1447-1461, May 2011. Supported in part by NPS.

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Meteorology and Physical Oceanography, 1981., Microfiche copy available in Archives and Science., Vita., Bibliography: leaves 140-145., by Frank Decatur Marks, Jr., Sc.D.

The U. S. Weather Research Program (USWRP) effort on hurricane landfall is focused on what the meteorological research community can contribute to a reduction in the nation's vulnerability to dangerous and costly impacts. Because of the growth in population (4.5% per year) and industry along the coast from Texas to Miami, the U. S. has become more vulnerable to tropical cyclones (TC). In coastal communities with limited escape routes, the emergency manager community must have accurate forecasts of coastal areas that will suffer damage, when the winds will exceed gale- force (35 kt) and heavy precipitation will arrive so that all disaster preparedness activities and evacuations can be completed safely. Another key forecast challenge is to predict the inner-core wind field (including maximum surface winds, or intensity) because the most intense hurricanes (categories 4 and 5)cause 80% of all damage. The inland flooding from the storm surge an heavy precipitation, localized regions of extreme wind damage, and severe local storms including tornadoes all depend on the inner-core wind field that is rapidly changing as the hurricane makes landfall.