Limitations of a linear model for the hurricane boundary layer

2009 ◽  
Vol 135 (641) ◽  
pp. 839-850 ◽  
Author(s):  
Stefanie Vogl ◽  
Roger K. Smith
Keyword(s):  
Boundary Layer ◽  
Linear Model ◽  
Hurricane Boundary Layer

scholarly journals An Analytical Model for the Regeneration of Wind after Exiting a Wind Farm

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2071
Author(s):  
Brian Fiedler
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Atmospheric Boundary Layer ◽  
Linear Model ◽  
Analytical Model ◽  
Environmental Conditions ◽  
Wind Farm ◽  
Length Scale ◽  
Equilibrium Calculation ◽  
Friction Pressure

The simplest model for an atmospheric boundary layer assumes a uniform steady wind over a certain depth, of order 1 km, with the forces of friction, pressure gradient and Coriolis in balance. A linear model is here employed for the adjustment of wind to this equilibrium, as the wake of a very wide wind farm. A length scale is predicted for the exponential adjustment to equilibrium. Calculation of this length scale is aided by knowledge of the angle for which the wind would normally cross the isobars in environmental conditions in the wake.

Finescale Dual-Doppler Analysis of Hurricane Boundary Layer Structures in Hurricane Frances (2004) at Landfall

2014 ◽  
Vol 142 (5) ◽  
pp. 1874-1891 ◽  
Author(s):  
Karen A. Kosiba ◽  
Joshua Wurman
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Transient Nature ◽  
Layer Structures ◽  
Characteristic Wavelength ◽  
Doppler Data ◽  
Mean Wind Speed ◽  
Average Flux ◽  
Hurricane Boundary Layer ◽  
The Right

Abstract Two Doppler on Wheels (DOW) mobile radars collected fine-spatial-scale dual-Doppler data in the right-front quadrant and eye of Hurricane Frances (2004) as it made landfall near Stuart, Florida. A 5.7-km dual-Doppler baseline established a dual-Doppler domain south and east of Fort Pierce, Florida, encompassing a 5.5 km × 5.5 km horizontal area, with a grid spacing of 20 m, allowing for the resolution of subkilometer-scale horizontal structures and associated kinematics. Three-dimensional vector wind analyses of the boundary layer revealed the presence of linear coherent structures with a characteristic wavelength of 400–500 m near the surface that increased in size and became more cellular in shape with increasing height. Average horizontal perturbation winds were proportional to average total horizontal winds. Within the eye of the hurricane, the features lost linear coherency despite a high mean wind speed, possibly due to changes in stability. A slight decrease in the characteristic wavelength of boundary layer structures was documented as the winds cross the barrier islands east of Fort Pierce. Vertical flux of horizontal momentum caused by individual vortical structures was substantially higher than values employed in turbulence parameterization schemes, but the domain-wide average flux was substantially lower than that in individual structures, likely due to the transient nature of the most intense portions of the structures. Analysis of the turbulent kinetic energy (TKE) yielded values comparable to those reported in previous observational studies over the open ocean. However, there was substantial variability in TKE within the dual-Doppler domain, emphasizing the challenge in obtaining representative samples using non-3D measurements such as dropsondes.

scholarly journals Effects of Vertical Eddy Diffusivity Parameterization on the Evolution of Landfalling Hurricanes

2017 ◽  
Vol 74 (6) ◽  
pp. 1879-1905 ◽  
Author(s):  
Feimin Zhang ◽  
Zhaoxia Pu
Keyword(s):  
Boundary Layer ◽  
Vertical Mixing ◽  
Eddy Diffusivity ◽  
Essential Components ◽  
Moisture Fluxes ◽  
Layer Velocity ◽  
Hurricane Boundary Layer ◽  
Heat And Moisture ◽  
Vertical Eddy Diffusivity ◽  
Vertical Eddy

Abstract As a result of rapid changes in surface conditions when a landfalling hurricane moves from ocean to land, interactions between the hurricane and surface heat and moisture fluxes become essential components of its evolution and dissipation. With a research version of the Hurricane Weather Research and Forecasting Model (HWRF), this study examines the effects of the vertical eddy diffusivity in the boundary layer on the evolution of three landfalling hurricanes (Dennis, Katrina, and Rita in 2005). Specifically, the parameterization scheme of eddy diffusivity for momentum Km is adjusted with the modification of the mixed-layer velocity scale in HWRF for both stable and unstable conditions. Results show that the change in the Km parameter leads to improved simulations of hurricane track, intensity, and quantitative precipitation against observations during and after landfall, compared to the simulations with the original Km. Further diagnosis shows that, compared to original Km, the modified Km produces stronger vertical mixing in the hurricane boundary layer over land, which tends to stabilize the hurricane boundary layer. Consequently, the simulated landfalling hurricanes attenuate effectively with the modified Km, while they mostly inherit their characteristics over the ocean and decay inefficiently with the original Km.

scholarly journals Effects of Boundary Layer Vertical Mixing on the Evolution of Hurricanes over Land

2017 ◽  
Vol 145 (6) ◽  
pp. 2343-2361 ◽  
Author(s):  
Feimin Zhang ◽  
Zhaoxia Pu ◽  
Chenghai Wang
Keyword(s):  
Boundary Layer ◽  
Positive Impact ◽  
Potential Temperature ◽  
Vertical Mixing ◽  
Vertical Wind Shear ◽  
Vertical Gradient ◽  
Weather Research And Forecasting ◽  
Virtual Potential Temperature ◽  
Dynamic Structures ◽  
Hurricane Boundary Layer

Abstract After a hurricane makes landfall, its evolution is strongly influenced by its interaction with the planetary boundary layer (PBL) over land. In this study, a series of numerical experiments are performed to examine the effects of boundary layer vertical mixing on hurricane simulations over land using a research version of the NCEP Hurricane Weather Research and Forecasting (HWRF) Model with three landfalling hurricane cases. It is found that vertical mixing in the PBL has a strong influence on the simulated hurricane evolution. Specifically, strong vertical mixing has a positive impact on numerical simulations of hurricanes over land, with better track, intensity, synoptic flow, and precipitation simulations. In contrast, weak vertical mixing leads to the strong hurricanes over land. Diagnoses of the thermodynamic and dynamic structures of hurricane vortices further suggest that the strong vertical mixing in the PBL could cause a decrease in the vertical wind shear and an increase in the vertical gradient of virtual potential temperature. As a consequence, these changes destroy the turbulence kinetic energy in the hurricane boundary layer and thus stabilize the hurricane boundary layer and limit its maintenance over land.

A quasi-empirical model of the hurricane boundary layer

1974 ◽  
Vol 79 (21) ◽  
pp. 3033-3040 ◽  
Author(s):  
Russell L. Elsberry ◽  
Nils A. S. Pearson ◽  
Leino B. Corgnati
Keyword(s):  
Boundary Layer ◽  
Empirical Model ◽  
Hurricane Boundary Layer
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