Estimation of Wind Speed in the Suburban Atmospheric Surface Layer

2016 ◽  
pp. 843-847
Author(s):  
Tanja Likso
Keyword(s):  
Surface Layer ◽  
Wind Speed ◽  
Atmospheric Surface Layer

scholarly journals The interaction between drifting snow and atmospheric turbulence

1998 ◽  
Vol 26 ◽  
pp. 167-173 ◽  
Author(s):  
Richard Bintanja
Keyword(s):  
Surface Layer ◽  
Wind Speed ◽  
Atmospheric Surface Layer ◽  
Order Approximation ◽  
Atmospheric Stability ◽  
Blowing Snow ◽  
Speed Profile ◽  
Stability Parameters ◽  
Wind Speed Profile ◽  
First Order

This paper presents a modelling study of the influence of suspended snow on turbulence in the atmospheric surface layer. Turbulence is diminished in drifting and blowing snow, since part of the turbulent energy is used to keep the particles in suspension. This decrease in turbulence directly affects the vertical turbulent fluxes of momentum and snow particles (and other scalars), and can effectively be simulated by introducing an appropriate Richardson number to account for the stability effects of the stably stratified air-snow mixture. We use a one-dimensional model of the atmospheric surface layer in which the Reynolds stress and turbulent suspended snow flux are parameterized in terms of their mean vertical gradients (first-order closure). The model calculates steady-state vertical profiles of mean wind speed, suspended snow mass in 16 size classes and stability parameters. Using the model, the influence of snowdrifting on the wind-speed profile is quantified for various values of the initial friction Velocity (which determines the steepness of the initial wind-speed profile). It will be demonstrated why the roughness length appears to increase when snowdrifting occurs. Finally, we present a parameterization of the effects of snowdrifting on atmospheric stability which can be used in data analyses as a first-order approximation.

scholarly journals The interaction between drifting snow and atmospheric turbulence

1998 ◽  
Vol 26 ◽  
pp. 167-173 ◽  
Author(s):  
Richard Bintanja
Keyword(s):  
Surface Layer ◽  
Wind Speed ◽  
Atmospheric Surface Layer ◽  
Order Approximation ◽  
Atmospheric Stability ◽  
Blowing Snow ◽  
Speed Profile ◽  
Stability Parameters ◽  
Wind Speed Profile ◽  
First Order

This paper presents a modelling study of the influence of suspended snow on turbulence in the atmospheric surface layer. Turbulence is diminished in drifting and blowing snow, since part of the turbulent energy is used to keep the particles in suspension. This decrease in turbulence directly affects the vertical turbulent fluxes of momentum and snow particles (and other scalars), and can effectively be simulated by introducing an appropriate Richardson number to account for the stability effects of the stably stratified air-snow mixture. We use a one-dimensional model of the atmospheric surface layer in which the Reynolds stress and turbulent suspended snow flux are parameterized in terms of their mean vertical gradients (first-order closure). The model calculates steady-state vertical profiles of mean wind speed, suspended snow mass in 16 size classes and stability parameters. Using the model, the influence of snowdrifting on the wind-speed profile is quantified for various values of the initial friction Velocity (which determines the steepness of the initial wind-speed profile). It will be demonstrated why the roughness length appears to increase when snowdrifting occurs. Finally, we present a parameterization of the effects of snowdrifting on atmospheric stability which can be used in data analyses as a first-order approximation.

scholarly journals A Statistical Model for the Prediction of Wind-Speed Probabilities in the Atmospheric Surface Layer

2016 ◽  
Vol 163 (2) ◽  
pp. 179-201 ◽  
Author(s):  
G. C. Efthimiou ◽  
D. Hertwig ◽  
S. Andronopoulos ◽  
J. G. Bartzis ◽  
O. Coceal
Keyword(s):  
Surface Layer ◽  
Wind Speed ◽  
Statistical Model ◽  
Atmospheric Surface Layer

Daily cycle of the surface layer and energy balance on the high Antarctic Plateau

2005 ◽  
Vol 17 (1) ◽  
pp. 121-133 ◽  
Author(s):  
DIRK VAN AS ◽  
MICHIEL VAN DEN BROEKE ◽  
RODERIK VAN DE WAL
Keyword(s):  
Heat Flux ◽  
Surface Layer ◽  
Energy Balance ◽  
Wind Speed ◽  
Atmospheric Surface Layer ◽  
Specific Humidity ◽  
Inertial Oscillation ◽  
Sensible Heat ◽  
Daily Cycle ◽  
Near Surface

This paper focuses on the daily cycle of the surface energy balance and the atmospheric surface layer during a detailed meteorological experiment performed near Kohnen base in Dronning Maud Land, East Antarctica, in January and February 2002. Temperature, specific humidity, wind speed and the turbulent scales of these quantities, exhibit a strong daily cycle. The sensible heat flux cycle has a mean amplitude of ∼8 W m−2, while the latent heat flux has an amplitude of less than 2 W m−2, which is small compared to the amplitude of net radiation (∼ 35 W m−2) and sub-surface heat (∼ 25 W m−2). Between ∼ 9 and 16 h GMT convection occurs due to a slightly unstable atmospheric surface layer. At the end of the afternoon, the wind speed decreases abruptly and the mixed layer is no longer supported by the sensible heat input; the stratification becomes stable. At night a large near-surface wind shear is measured due to the presence of a nocturnal jet, which is likely to be katabatically driven, but can also be the result of an inertial oscillation. No strong daily cycle in wind direction is recorded, since both the katabatic forcing at night and the daytime forcing by the large-scale pressure gradient were directed approximately downslope during the period of measurement.

Factors controlling the latent and sensible heat fluxes over Erhai Lake under different atmospheric surface layer stability conditions

2020 ◽  
Author(s):  
Xiaoni Meng ◽  
Huizhi Liu
Keyword(s):  
Surface Layer ◽  
Wind Speed ◽  
Pressure Difference ◽  
Atmospheric Surface Layer ◽  
Heat Fluxes ◽  
Stability Conditions ◽  
Erhai Lake ◽  
Stable Range ◽  
Weakly Stable ◽  
The Stability

<p>The stratification of atmospheric surface layer (ASL) plays an important role in regulating the water vapour and heat exchange across lake-air interface. Based on one-year data measured by Eddy Covariance (EC) technique over Erhai Lake in 2015, the ASL stability (ζ) was divided into six ranges, including unstable, weakly unstable, near-neutral(unstable side), near-neutral(stable side), weakly stable, and stable range. The characteristic of ASL stability conditions and factors controlling the latent (LE) and sensible (H) heat fluxes under different stability conditions were analyzed in this study. The stability conditions of Erhai Lake have noticeably seasonal and diurnal variation, which the near-neutral and (weakly)stable stratification usually occurred before July with frequency of 51.7% and 23.3%, respectively, but most of the (weakly)unstable stratification was observed since July with frequency of 59.8%. Large evaporation occurred even in stable atmospheric conditions, due to the coupled effects of relative larger lake-air vapor pressure difference and wind speed. The relative controls of LE and H by different atmospheric variables are largely dependent on the stability conditions. In stable and unstable range, LE is closely correlated with vapour pressure difference, whereas in weakly unstable to weakly stable range, LE is primarily controlled by wind speed. H is related to wind speed and lake-air temperature difference under stable conditions, but shows no obvious relationship under unstable conditions.</p>

Prediction of the wind speed probabilities in the atmospheric surface layer

2019 ◽  
Vol 132 ◽  
pp. 921-930 ◽  
Author(s):  
G.C. Efthimiou ◽  
P. Kumar ◽  
S.G. Giannissi ◽  
A.A. Feiz ◽  
S. Andronopoulos
Keyword(s):  
Surface Layer ◽  
Wind Speed ◽  
Atmospheric Surface Layer

scholarly journals Surface-layer turbulence, energy balance and links to atmospheric circulations over a mountain glacier in the French Alps

2017 ◽  
Vol 11 (2) ◽  
pp. 971-987 ◽  
Author(s):  
Maxime Litt ◽  
Jean-Emmanuel Sicart ◽  
Delphine Six ◽  
Patrick Wagnon ◽  
Warren D. Helgason
Keyword(s):  
Surface Layer ◽  
Energy Balance ◽  
Wind Speed ◽  
Eddy Covariance ◽  
Large Scale ◽  
Atmospheric Surface Layer ◽  
Turbulent Fluxes ◽  
Profile Method ◽  
Wind Speed Maximum ◽  
Roughness Lengths

Abstract. Over Saint-Sorlin Glacier in the French Alps (45° N, 6.1° E; ∼ 3 km2) in summer, we study the atmospheric surface-layer dynamics, turbulent fluxes, their uncertainties and their impact on surface energy balance (SEB) melt estimates. Results are classified with regard to large-scale forcing. We use high-frequency eddy-covariance data and mean air-temperature and wind-speed vertical profiles, collected in 2006 and 2009 in the glacier's atmospheric surface layer. We evaluate the turbulent fluxes with the eddy-covariance (sonic) and the profile method, and random errors and parametric uncertainties are evaluated by including different stability corrections and assuming different values for surface roughness lengths. For weak synoptic forcing, local thermal effects dominate the wind circulation. On the glacier, weak katabatic flows with a wind-speed maximum at low height (2–3 m) are detected 71 % of the time and are generally associated with small turbulent kinetic energy (TKE) and small net turbulent fluxes. Radiative fluxes dominate the SEB. When the large-scale forcing is strong, the wind in the valley aligns with the glacier flow, intense downslope flows are observed, no wind-speed maximum is visible below 5 m, and TKE and net turbulent fluxes are often intense. The net turbulent fluxes contribute significantly to the SEB. The surface-layer turbulence production is probably not at equilibrium with dissipation because of interactions of large-scale orographic disturbances with the flow when the forcing is strong or low-frequency oscillations of the katabatic flow when the forcing is weak. In weak forcing when TKE is low, all turbulent fluxes calculation methods provide similar fluxes. In strong forcing when TKE is large, the choice of roughness lengths impacts strongly the net turbulent fluxes from the profile method fluxes and their uncertainties. However, the uncertainty on the total SEB remains too high with regard to the net observed melt to be able to recommend one turbulent flux calculation method over another.

scholarly journals Stability and Sea State as Limiting Conditions for TKE Dissipation and Dissipative Heating

2019 ◽  
Vol 76 (3) ◽  
pp. 689-706
Author(s):  
Andrew W. Smith ◽  
Brian K. Haus ◽  
Jun A. Zhang
Keyword(s):  
Surface Layer ◽  
Wind Speed ◽  
Dissipation Rate ◽  
Atmospheric Surface Layer ◽  
Surface Wind ◽  
Dissipative Heating ◽  
Eddy Correlation ◽  
Neutral Stability ◽  
Sea State ◽  
Tke Dissipation Rate

Abstract This study analyzes high-resolution ship data collected in the Gulf of Mexico during the Lagrangian Submesoscale Experiment (LASER) from January to February 2016 to produce the first reported measurements of dissipative heating in the explicitly nonhurricane atmospheric surface layer. Although typically computed from theory as a function of wind speed cubed, the dissipative heating directly estimated via the turbulent kinetic energy (TKE) dissipation rate is also presented. The dissipative heating magnitude agreed with a previous study that estimated the dissipative heating in the hurricane boundary layer using in situ aircraft data. Our observations that the 10-m neutral drag coefficient parameterized using TKE dissipation rate approaches zero slope as wind increases suggests that TKE dissipation and dissipative heating are constrained to a physical limit. Both surface-layer stability and sea state were observed to be important conditions influencing dissipative heating, with the stability determined via TKE budget terms and the sea state determined via wave steepness and age using direct shipboard measurements. Momentum and enthalpy fluxes used in the TKE budget are determined using the eddy-correlation method. It is found that the TKE dissipation rate and the dissipative heating are largest in a nonneutral atmospheric surface layer with a sea surface comprising steep wind sea and slow swell waves at a given surface wind speed, whereas the ratio of dissipative heating to enthalpy fluxes is largest in near-neutral stability where the turbulent vertical velocities are near zero.

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