A first order geometric auto regressive process for boundary layer wind speed simulation

Abstract Atmospheric turbulence is an unsteady phenomenon found in nature and plays significance role in predicting natural events and life prediction of structures. In this work, turbulence in surface boundary layer has been studied through empirical methods. Computer simulation of Von Karman, Kaimal methods were evaluated for different surface roughness and for low (1%), medium (10%) and high (50%) turbulence intensities. Instantaneous values of one minute time series for longitudinal turbulent wind at mean wind speed of 12 m/s using both spectra showed strong correlation in validation trends. Influence of integral length scales on turbulence kinetic energy production at different heights is illustrated. Time series for mean wind speed of 12 m/s with surface roughness value of 0.05 m have shown that variance for longitudinal, lateral and vertical velocity components were different and found to be anisotropic. Wind speed power spectral density from Davenport and Simiu profiles have also been calculated at surface roughness of 0.05 m and compared with k−1 and k−3 slopes for Kolmogorov k−5/3 law in inertial sub-range and k−7 in viscous dissipation range. At high frequencies, logarithmic slope of Kolmogorov −5/3rd law agreed well with Davenport, Harris, Simiu and Solari spectra than at low frequencies.

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Nonlinear Theory for Flexural Motions of Thin Elastic Plate, Part 3: Numerical Evaluation of Boundary Layer Solutions

Journal of Applied Mechanics ◽

10.1115/1.3162102 ◽

1982 ◽

Vol 49 (2) ◽

pp. 409-416

Author(s):

N. Sugimoto

Keyword(s):

Boundary Layer ◽

Stress Singularity ◽

Free Edge ◽

Thin Elastic Plate ◽

Normal Stresses ◽

Interior Region ◽

First Order ◽

Plausible Values ◽

Bending Stresses ◽

Order Stress

The boundary layer solutions previoulsy obtained in Part 2 of this series for the cases of the built-in edge and the free edge are evaluated numerically. For the built-in edge, a characteristic penetration depth of the boundary layer toward the interior region is given by 0.13 εh, εh being the normalized thickness of the plate, while for the free edge, it is given by 0.32 εh. Thus the boundary layer for the free edge penetrates more deeply toward the interior region than that for the built-in edge. The first-order stress distribution in each boundary layer is displayed. For the built-in edge, the stress singularity appears on the edge. It is shown that, in the boundary layer, the shearing and normal stresses become comparable with the bending stresses. Similarly for the free edge, the shearing stress also becomes comparable with the twisting stress. It should be remarked that, in the boundary layer, the shearing or the normal stress plays a primarily important role as the bending or the twisting stress. But the former decays toward the interior region and remains higher order than the latter. Finally owing to these numerical results, the coefficients involved in the “reduced” boundary conditions for the built-in edge are evaluated for the various plausible values of Poisson’s ratio.

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Variable Eddy Viscosities in the Atmospheric Boundary Layer from Ageostrophic Wind-Speed Profiles

Journal of Mathematical Fluid Mechanics ◽

10.1007/s00021-021-00575-1 ◽

2021 ◽

Vol 23 (2) ◽

Author(s):

Tony Lyons

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Atmospheric Boundary Layer ◽

Ageostrophic Wind

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Unexpected vertical wind speed profiles in the boundary layer over the southern North Sea

Journal of Wind Engineering and Industrial Aerodynamics ◽

10.1016/j.jweia.2014.07.012 ◽

2014 ◽

Vol 134 ◽

pp. 149-162 ◽

Cited By ~ 15

Author(s):

Anthony J. Kettle

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

North Sea ◽

Vertical Wind ◽

Southern North Sea ◽

Vertical Wind Speed

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Modeling the Atmospheric Boundary Layer Wind Response to Mesoscale Sea Surface Temperature Perturbations

Monthly Weather Review ◽

10.1175/mwr-d-13-00332.1 ◽

2014 ◽

Vol 142 (11) ◽

pp. 4284-4307 ◽

Cited By ~ 30

Author(s):

Natalie Perlin ◽

Simon P. de Szoeke ◽

Dudley B. Chelton ◽

Roger M. Samelson ◽

Eric D. Skyllingstad ◽

...

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Surface Temperature ◽

Sea Surface Temperature ◽

Coupling Coefficient ◽

Eddy Viscosity ◽

Sea Surface ◽

Coupling Coefficients ◽

Wind Response ◽

Speed Response

Abstract The wind speed response to mesoscale SST variability is investigated over the Agulhas Return Current region of the Southern Ocean using the Weather Research and Forecasting (WRF) Model and the U.S. Navy Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) atmospheric model. The SST-induced wind response is assessed from eight simulations with different subgrid-scale vertical mixing parameterizations, validated using Quick Scatterometer (QuikSCAT) winds and satellite-based sea surface temperature (SST) observations on 0.25° grids. The satellite data produce a coupling coefficient of sU = 0.42 m s−1 °C−1 for wind to mesoscale SST perturbations. The eight model configurations produce coupling coefficients varying from 0.31 to 0.56 m s−1 °C−1. Most closely matching QuikSCAT are a WRF simulation with the Grenier–Bretherton–McCaa (GBM) boundary layer mixing scheme (sU = 0.40 m s−1 °C−1), and a COAMPS simulation with a form of Mellor–Yamada parameterization (sU = 0.38 m s−1 °C−1). Model rankings based on coupling coefficients for wind stress, or for curl and divergence of vector winds and wind stress, are similar to that based on sU. In all simulations, the atmospheric potential temperature response to local SST variations decreases gradually with height throughout the boundary layer (0–1.5 km). In contrast, the wind speed response to local SST perturbations decreases rapidly with height to near zero at 150–300 m. The simulated wind speed coupling coefficient is found to correlate well with the height-averaged turbulent eddy viscosity coefficient. The details of the vertical structure of the eddy viscosity depend on both the absolute magnitude of local SST perturbations, and the orientation of the surface wind to the SST gradient.

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Observed Boundary Layer Wind Structure and Balance in the Hurricane Core. Part I: Hurricane Georges

Journal of the Atmospheric Sciences ◽

10.1175/jas3745.1 ◽

2006 ◽

Vol 63 (9) ◽

pp. 2169-2193 ◽

Cited By ~ 101

Author(s):

Jeffrey D. Kepert

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Tropical Cyclone ◽

Radial Profile ◽

Lower Altitude ◽

Near Surface ◽

Wind Structure ◽

The Right ◽

Tropical Cyclone Boundary Layer ◽

Upper Boundary

Abstract The GPS dropsonde allows observations at unprecedentedly high horizontal and vertical resolution, and of very high accuracy, within the tropical cyclone boundary layer. These data are used to document the boundary layer wind field of the core of Hurricane Georges (1998) when it was close to its maximum intensity. The spatial variability of the boundary layer wind structure is found to agree very well with the theoretical predictions in the works of Kepert and Wang. In particular, the ratio of the near-surface wind speed to that above the boundary layer is found to increase inward toward the radius of maximum winds and to be larger to the left of the track than to the right, while the low-level wind maximum is both more marked and at lower altitude on the left of the storm track than on the right. However, the expected supergradient flow in the upper boundary layer is not found, with the winds being diagnosed as close to gradient balance. The tropical cyclone boundary layer model of Kepert and Wang is used to simulate the boundary layer flow in Hurricane Georges. The simulated wind profiles are in good agreement with the observations, and the asymmetries are well captured. In addition, it is found that the modeled flow in the upper boundary layer at the eyewall is barely supergradient, in contrast to previously studied cases. It is argued that this lack of supergradient flow is a consequence of the particular radial structure in Georges, which had a comparatively slow decrease of wind speed with radius outside the eyewall. This radial profile leads to a relatively weak gradient of inertial stability near the eyewall and a strong gradient at larger radii, and hence the tropical cyclone boundary layer dynamics described by Kepert and Wang can produce only marginally supergradient flow near the radius of maximum winds. The lack of supergradient flow, diagnosed from the observational analysis, is thus attributed to the large-scale structure of this particular storm. A companion paper presents a similar analysis for Hurricane Mitch (1998), with contrasting results.

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Meteorological observations of the coastal boundary layer structure at the Bulgarian Black Sea coast

Advances in Science and Research ◽

10.5194/asr-6-251-2011 ◽

2011 ◽

Vol 6 (1) ◽

pp. 251-259 ◽

Cited By ~ 5

Author(s):

D. Barantiev ◽

M. Novitsky ◽

E. Batchvarova

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Black Sea ◽

Vertical Structure ◽

Sonic Anemometer ◽

Sea Breeze ◽

Turbulence Measurements ◽

Black Sea Coast ◽

Meteorological Observatory ◽

Sea Coast

Abstract. Continuous wind profile and turbulence measurements were initiated in July 2008 at the coastal meteorological observatory of Ahtopol on the Black Sea (south-east Bulgaria) under a Bulgarian-Russian collaborative program. These observations are the start of high resolution atmospheric boundary layer vertical structure climatology at the Bulgarian Black Sea coast using remote sensing technology and turbulence measurements. The potential of the measurement program with respect to this goal is illustrated with examples of sea breeze formation and characteristics during the summer of 2008. The analysis revealed three distinct types of weather conditions: no breeze, breeze with sharp frontal passage and gradually developing breeze. During the sea breeze days, the average wind speed near the ground (from sonic anemometer at 4.5 m and first layer of sodar at 30–40 m) did not exceed 3–4 m s−1. The onset of breeze circulation was detected based on surface layer measurements of air temperature (platinum sensor and acoustic), wind speed and direction, and turbulence parameters. The sodar measurements revealed the vertical structure of the wind field.

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Evaluation of the AMPS Boundary Layer Simulations on the Ross Ice Shelf, Antarctica, with Unmanned Aircraft Observations

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-16-0339.1 ◽

2017 ◽

Vol 56 (8) ◽

pp. 2239-2258 ◽

Cited By ~ 6

Author(s):

Jonathan D. Wille ◽

David H. Bromwich ◽

John J. Cassano ◽

Melissa A. Nigro ◽

Marian E. Mateling ◽

...

Keyword(s):

Boundary Layer ◽

Wind Speed ◽

Relative Humidity ◽

High Wind ◽

Ice Shelf ◽

High Wind Speed ◽

Near Surface ◽

Ross Ice Shelf ◽

Low Cloud ◽

The Antarctic

AbstractAccurately predicting moisture and stability in the Antarctic planetary boundary layer (PBL) is essential for low-cloud forecasts, especially when Antarctic forecasters often use relative humidity as a proxy for cloud cover. These forecasters typically rely on the Antarctic Mesoscale Prediction System (AMPS) Polar Weather Research and Forecasting (Polar WRF) Model for high-resolution forecasts. To complement the PBL observations from the 30-m Alexander Tall Tower! (ATT) on the Ross Ice Shelf as discussed in a recent paper by Wille and coworkers, a field campaign was conducted at the ATT site from 13 to 26 January 2014 using Small Unmanned Meteorological Observer (SUMO) aerial systems to collect PBL data. The 3-km-resolution AMPS forecast output is combined with the global European Centre for Medium-Range Weather Forecasts interim reanalysis (ERAI), SUMO flights, and ATT data to describe atmospheric conditions on the Ross Ice Shelf. The SUMO comparison showed that AMPS had an average 2–3 m s−1 high wind speed bias from the near surface to 600 m, which led to excessive mechanical mixing and reduced stability in the PBL. As discussed in previous Polar WRF studies, the Mellor–Yamada–Janjić PBL scheme is likely responsible for the high wind speed bias. The SUMO comparison also showed a near-surface 10–15-percentage-point dry relative humidity bias in AMPS that increased to a 25–30-percentage-point deficit from 200 to 400 m above the surface. A large dry bias at these critical heights for aircraft operations implies poor AMPS low-cloud forecasts. The ERAI showed that the katabatic flow from the Transantarctic Mountains is unrealistically dry in AMPS.

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