On the hyperbolicity of the bulk air-sea heat flux functions: Insights into the efficiency of air-sea moisture disequilibrium for tropical cyclone intensification

Sea-to-air heat fluxes are the energy source for tropical cyclone (TC) development and maintenance. In the bulk aerodynamic formulas, these fluxes are a function of surface wind speed U10 and air-sea temperature and moisture disequilibrium (ΔT and Δq, respectively). Although many studies have explained TC intensification through the mutual dependence between increasing U10 and increasing sea-to-air heat fluxes, recent studies have found that TC intensification can occur through deep convective vortex structures that obtain their local buoyancy from sea-to-air moisture fluxes, even under conditions of relatively low wind. Herein, a new perspective on the bulk aerodynamic formulas is introduced to evaluate the relative contribution of wind-driven (U10) and thermodynamically driven (ΔT and Δq) ocean heat uptake. Previously unnoticed salient properties of these formulas, reported here, are as follows: 1) these functions are hyperbolic and 2) increasing Δq is an efficient mechanism for enhancing the fluxes. This new perspective was used to investigate surface heat fluxes in six TCs during phases of steady-state intensity (SS), slow intensification (SI), and rapid intensification (RI). A capping of wind-driven heat uptake was found during periods of SS, SI, and RI. Compensation by larger values of Δq . 5 gkg-1 at moderate values of U10 led to intense inner-core moisture fluxes of greater than 600Wm22 during RI. Peak values in Δq preferentially occurred over oceanic regimes with higher sea surface temperature (SST) and upper-ocean heat content. Thus, increasing SST and Δq is a very effective way to increase surface heat fluxes-this can easily be achieved as a TC moves over deeper warm oceanic regimes

Wind Speed Dependence of Single-Site Wave-Height Retrievals from High-Frequency Radars

Wave-height observations derived from single-site high-frequency (HF) radar backscattered Doppler spectra are generally recognized to be less accurate than overlapping radar techniques but can provide significantly larger sampling regions. The larger available wave-sampling region may have important implications for observing system design. Comparison of HF radar–derived wave heights with acoustic Doppler profiler and buoy data revealed that the scale separation between the Bragg scattering waves and the peak energy-containing waves may contribute to errors in the single-site estimates in light-to-moderate winds. A wave-height correction factor was developed that explicitly considers this scale separation and eliminates the trend of increasing errors with increasing wind speed

Development of a National Pain Management Competency Profile to Guide Entry-Level Physiotherapy Education in Canada

Background National strategies from North America call for substantive improvements in entry-level pain management education to help reduce the burden of chronic pain. Past work has generated a valuable set of interprofessional pain management competencies to guide the education of future health professionals. However, there has been very limited work that has explored the development of such competencies for individual professions in different regions. Developing profession-specific competencies tailored to the local context is a necessary first step to integrate them within local regulatory systems. Our group is working toward this goal within the context of entry-level physiotherapy (PT) programs across Canada. Aims This study aimed to create a consensus-based competency profile for pain management, specific to the Canadian PT context. Methods A modified Delphi design was used to achieve consensus across Canadian university-based and clinical pain educators. Results Representatives from 14 entry-level PT programs (93% of Canadian programs) and six clinical educators were recruited. After two rounds, a total of 15 competencies reached the predetermined endorsement threshold (75%). Most participants (85%) reported being “very satisfied” with the process. Conclusions This process achieved consensus on a novel pain management competency profile specific to the Canadian PT context. The resulting profile delineates the necessary abilities required by physiotherapists to manage pain upon entry to practice. Participants were very satisfied with the process. This study also contributes to the emerging literature on integrated research in pain management by profiling research methodology that can be used to inform related work in other health professions and regions

Observational/numerical study of the upper ocean response to hurricanes.

http://archive.org/details/observationalnum00shayNAN

Ocean-atmosphere interactions in tropical cyclones

Over the past two decades, there has been increased interest in not only understanding the ocean response to tropical cyclone (TC) forcing, but the impact of the ocean on intensity and structural change in the TC itself. The oceanic response has been primarily studied in the context of the baroclinic wake left by TC's and the forced near-inertial waves as observed in Gilbert (88), Frances, and Ivan (04). This cold wake structure and the negative feedback are due to ocean mixed layer cooling by shear-induced vertical mixing by near-inertial motions forced by TC momentum flux. That is, the strong shears lower the Richardson numbers to below criticality that forces the entrainment of cooler water from the seasonal thermocline that may lead to TC weakening. Notwithstanding, in some oceanic regimes these cold wakes (>2ºC) simply do not develop over deep warm oceanic features. Background oceanic states impact upper ocean thermal response where the warm layers are deeper and currents transport warm water poleward as part of the gyre circulation as suggested by measurements in Isidore and Lili (02), Katrina and Rita (05), and Gustav and Ike (08) over the Loop Current. In these regimes, the wind-driven shears do not develop and essentially keep the oceanic mixed layer warm with high oceanic heat content levels (>100 kJ cm-2) during TC passage. The implication is a more sustained enthalpy flux to the atmospheric boundary layer, thus representing an important heat and moisture source for deepening of TCs.In this broader context, recent studies have shown the surface drag coefficient to level off between 28 to 33 m s-1 at values from 2.4 to 3.4 x 10-3. For intense TCs, the theoretical ratio of the enthalpy and surface drag coefficient ranges exceeds unity (typically 1.2 to 1.5), and when this ratio is less than unity, studies suggest that TCs cannot reach their maximum intensity. The important point here is that these fluids are coupled if we ever expect a more accurate intensity forecast, the enthalpy fluxes (and aerodynamic transfer coefficients) must be correct

Observations of inertio-gravity waves in the wake of hurricane Frederic.

Provider: Biodiversity Heritage Library - Institution: Naval Postgraduate School - Data provided by Europeana Collections- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including EuropeanaThesis (M.S. in Ocean.)--Naval Postgraduate School, 198

Free Surface Effects on the Near-Inertial Ocean Current Response to a Hurricane

During the passage of hurricane Frederic in 1979, four ocean current meter arrays in water depths of 100- 950 m detected both a barociinic and a depth-independent response in the near-inertial frequency band. Although the oceanic response was predominately barociinic, the hurricane excited a depth-independent component of 5-11 cm S-I. The origin and role of the depth-independent component of velocity is investigated using a linear analytical model and numerical simulations from a 17-level primitive equation model with a free surface. Both models are forced with an idealized wind stress pattern based on the observed storm parameters in hurricane Frederic. In an analytical model, the Green's function (Ko) is convolved with the wind stress curl to predict a sea surface depression of approximately 20 cm from the equilibrium position. The near-inertial velocities are simulated by convolving the slope of the sea surface depression with a second Green's function. The barotropic current velocities rotate inertially with periods shifted above the local inertial period by I %-2% and the maximum amplitude of II cm S-I is displaced to the right of the track at x = 2Rmax (radius of maximum winds). The free surface depression simulated by the primitive-equation model is also about 18-20 cm. The primitive equation model simulations indicate that the vertical mean pressure gradient excites 10-11 cm S-I depthaveraged currents atx = 3Rmax . The net divergence and convergence of the horizontal velocities induces vertical deflections of the sea surface. The spatial pattern of the barotropic amplitudes simulated by the numerical and analytical models differ by less than 2 cm S-I in the region 0 which suggests that the barotropic response to the passage of a moving hurricane is governed by linear processes

Mixed Layer Cooling in Mesoscale Oceanic Eddies during Hurricanes Katrina and Rita

Abstract During favorable atmospheric conditions, Hurricanes Katrina and Rita deepened to category 5 over the Loop Current’s (LC) bulge associated with an amplifying warm core eddy. Both hurricanes subsequently weakened to category 3 after passing over a cold core eddy (CCE) prior to making landfall. Reduced (increased) oceanic mixed layer (OML) cooling of ∼1°C (4.5°C) was observed over the LC (CCE) where the storms rapidly deepened (weakened). Data acquired during and subsequent to the passage of both hurricanes indicate that the modulated velocity response in these geostrophic features was responsible for the contrasts in the upper-ocean cooling levels. For similar wind forcing, the OML velocity response was about 2 times larger inside the CCE that interacted with Katrina than in the LC region affected by Rita, depending on the prestorm OML thickness. Hurricane-induced upwelling and vertical mixing were increased (reduced) in the CCE (LC). Less wind-driven kinetic energy was available to increase vertical shears for entrainment cooling in the LC, as the OML current response was weaker and energy was largely radiated into the thermocline. Estimates of downward vertical radiation of near-inertial wave energies were significantly stronger in the LC (12.1 × 10−2 W m−2) than in the CCE (1.8 × 10−2 W m−2). Katrina and Rita winds provided O(1010) W to the global internal wave power. The vertical mixing induced by both storms was confined to the surface water mass. From a broader perspective, models must capture oceanic features to reproduce the differentiated hurricane-induced OML cooling to improve hurricane intensity forecasting