Porosity and Drag Determination of a Single-Row Vegetative Barrier (Maclura pomifera)

2018 ◽  
Vol 61 (2) ◽  
pp. 641-652 ◽  
Author(s):  
Howell B. Gonzales ◽  
Mark E. Casada ◽  
Lawrence J. Hagen ◽  
John Tatarko ◽  
Ronaldo G. Maghirang ◽  
...  
Keyword(s):  
Drag Coefficient ◽  
Great Plains ◽  
Wind Erosion ◽  
Mean Values ◽  
Single Row ◽  
Wind Speeds ◽  
Osage Orange ◽  
Vegetative Barrier ◽  
Different Seasons ◽  
Calm Wind

Abstract. Deciduous trees of the species (Osage orange) are commonly established as vegetative barriers for wind erosion control throughout the U.S. Great Plains. Because there is no previous research on the aerodynamic effectiveness of these vegetative barriers during different seasons (leaf-on and leaf-off conditions), this study focused on determining the porosity and drag characteristics of this tree species. Digital image analyses were used to determine optical porosities that were then correlated with barrier drag coefficients. Images were taken in the field during calm wind conditions when the sunlight was suitable for digital imaging. Wind speeds were measured at different heights for a single-row Osage orange barrier using cup anemometers. Two anemometer towers were positioned relative to the barrier. One was located windward at 10H distance from the barrier; the other was located leeward and was movable to distances of 1H, 2H, 4H, 7H, 10H, 12H, 15H, and 20H from the barrier, where H is the average barrier height. The wind speeds measured in the field ranged from 4 to 7 m s-1, with lower wind speeds encountered during the leaf-off condition. As expected, wind speed reductions were greater for the leaf-on condition and ranged from 40% to 80% at 1H from the barrier, while the reduction was 20% to 38% for the leaf-off condition. The crown portion of the barrier was found to be responsible for much of the reduction. Mean values of the drag coefficient were 1.3 for the leaf-on condition, decreasing to 0.9 for the leaf-off condition of the Osage orange barrier, which corresponded to mean optical porosities of 20% and 61%, respectively Keywords: Drag coefficient, Image analysis, Osage orange, Porosity, Vegetative barrier, Wind erosion.

Dust Reduction Efficiency of a Single-Row Vegetative Barrier (Maclura pomifera)

2018 ◽  
Vol 61 (6) ◽  
pp. 1907-1914
Author(s):  
Howell B. Gonzales ◽  
John Tatarko ◽  
Mark E. Casada ◽  
Ronaldo G. Maghirang ◽  
Lawrence J. Hagen ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Great Plains ◽  
Wind Erosion ◽  
Dust Removal ◽  
Dust Particles ◽  
Deciduous Tree ◽  
Single Row ◽  
Osage Orange ◽  
Reduction Efficiency ◽  
Dust Reduction

Little is known about the dust removal efficiency of common vegetative barriers. This study of blowing dust reduction was conducted on one of the most common vegetative barriers used for wind erosion control in Kansas and the U.S. Great Plains, the deciduous tree species (Osage orange). A dust generator and distributor were fabricated to generate dust particles for determining the dust removal efficiency of a single-row Osage orange barrier. Simultaneous upwind and downwind dust concentrations were measured using mini-vol samplers for total suspended particulates (TSP) at heights of 1.5, 3.0, 4.5, and 6.0 m above the ground. Measurements were made using two towers located at upwind and downwind distances equal to the height of the barrier. Particle size distribution (PSD) analysis of the initial generated dust showed that most particles were large (GMD = 102.8 µm), while about 5% of the dust was particulate matter less than 2.5 µm in diameter (PM2.5) and 15% was less than 10 µm (PM10). Laser diffraction analysis of particles from the sample filters was used to determine the dust reduction efficiency of the barrier. Results showed that dust reduction was significantly related to reduction in wind speed at lower heights, causing an overall decrease in dust concentration as particles passed through the barrier. Concentrations of larger particles (~100 µm) were also reduced relative to smaller particles when dust passed through the barrier. The data also showed that 4.5 m above the ground, near the crown of the canopy, was most efficient at removing the PM2.5 (15% to 54%) and PM10 (23% to 65%) fractions of the generated dust. Keywords: Generated dust, Osage orange, PM2.5, PM10, TSP, Wind erosion.

scholarly journals A Novel Sea Surface Roughness Parameterization Based on Wave State and Sea Foam

2021 ◽  
Vol 9 (3) ◽  
pp. 246
Author(s):  
Difu Sun ◽  
Junqiang Song ◽  
Xiaoyong Li ◽  
Kaijun Ren ◽  
Hongze Leng
Keyword(s):  
Surface Roughness ◽  
Wind Speed ◽  
Drag Coefficient ◽  
Sea Surface ◽  
High Wind Speed ◽  
Wave State ◽  
Wind Speeds ◽  
Sea Surface Roughness ◽  
Extreme Wind ◽  
The Impact

A wave state related sea surface roughness parameterization scheme that takes into account the impact of sea foam is proposed in this study. Using eight observational datasets, the performances of two most widely used wave state related parameterizations are examined under various wave conditions. Based on the different performances of two wave state related parameterizations under different wave state, and by introducing the effect of sea foam, a new sea surface roughness parameterization suitable for low to extreme wind conditions is proposed. The behaviors of drag coefficient predicted by the proposed parameterization match the field and laboratory measurements well. It is shown that the drag coefficient increases with the increasing wind speed under low and moderate wind speed conditions, and then decreases with increasing wind speed, due to the effect of sea foam under high wind speed conditions. The maximum values of the drag coefficient are reached when the 10 m wind speeds are in the range of 30–35 m/s.

scholarly journals Relationship between Sea Surface Drag Coefficient and Wave State

2021 ◽  
Vol 9 (11) ◽  
pp. 1248
Author(s):  
Jian Shi ◽  
Zhihao Feng ◽  
Yuan Sun ◽  
Xueyan Zhang ◽  
Wenjing Zhang ◽  
...  
Keyword(s):  
Drag Coefficient ◽  
Momentum Flux ◽  
Sea Surface ◽  
Sea Spray ◽  
Wave Age ◽  
High Wind ◽  
Surface Drag ◽  
Wave State ◽  
Wind Speeds ◽  
Strong Winds

The sea surface drag coefficient plays an important role in momentum transmission between the atmosphere and the ocean, which is affected by ocean waves. The total air–sea momentum flux consists of effective momentum flux and sea spray momentum flux. Sea spray momentum flux involves sea surface drag, which is largely affected by the ocean wave state. Under strong winds, the sea surface drag coefficient (CD) does not increase linearly with the increasing wind speed, namely, the increase of CD is inhibited by strong winds. In this study, a sea surface drag coefficient is constructed that can be applied to the calculation of the air–sea momentum flux under high wind speed. The sea surface drag coefficient also considers the influence of wave state and sea spray droplets generated by wave breaking. Specially, the wave-dependent sea spray generation function is employed to calculate sea spray momentum flux. This facilitates the analysis not only on the sensitivity of the sea spray momentum flux to wave age, but also on the effect of wave state on the effective CD (CD, eff) under strong winds. Our results indicate that wave age plays an important role in determining CD. When the wave age is >0.4, CD decreases with the wave age. However, when the wave age is ≤0.4, CD increases with the wave age at low and moderate wind speeds but tends to decrease with the wave age at high wind speeds.

Galactic cosmic-ray modulation effect by solar-wind streams

1995 ◽  
Vol 73 (9-10) ◽  
pp. 642-646 ◽  
Author(s):  
M. A. El-Borie
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Cosmic Rays ◽  
Solar Wind Speed ◽  
Cosmic Ray ◽  
Diurnal Variations ◽  
Solar Cycles ◽  
Mean Values ◽  
Wind Speeds ◽  
Cosmic Ray Modulation

Data, from the worldwide network of neutron monitors, recorded at Deep River, Hermanus, Rome, Tokyo, and Huancayo, over two solar cycles (Nos. 20 and 21) are analyzed to study the long-term variations of the solar diurnal variations as they relate to solar-wind speed. The median primary rigidities of response (Rm) for these detectors cover the range 16 GV ≤ Rm ≤ 33 GV. We discuss the solar diurnal variations (amplitude and phase) of cosmic rays as a function of solar activity. The behavior of solar diurnal phases is completely different for the two epochs of high-wind speed. Data of solar-wind speed from 1966–1986 are classified according to the state of the daily mean values. Variation in the amplitudes of the diurnal variations, as functions of the median primary rigidity of cosmic rays, for the two selected periods (1973–1975 and 1979–1981) of high and low solar-wind speeds were determined at the selected stations. The rigidity dependence of the averaged solar diurnal variations of cosmic rays related to the high solar-wind speed was studied. The most sensitive rigidity of modulation is around 20 and 30 GV during the 1973–1975 and 1979–1981 periods, respectively. Our results also show that there is a significant correlation in the solar diurnal amplitudes between the two divisions of high and low solar-wind speed days.

scholarly journals Impact of the Reduced Drag Coefficient on Ocean Wave Modeling under Hurricane Conditions

2008 ◽  
Vol 136 (3) ◽  
pp. 1217-1223 ◽  
Author(s):  
Il-Ju Moon ◽  
Isaac Ginis ◽  
Tetsu Hara
Keyword(s):  
Drag Coefficient ◽  
Hurricane Katrina ◽  
Wind Wave ◽  
Wave Model ◽  
High Wind ◽  
Model Surface ◽  
Wind Speeds ◽  
Tank Experiment ◽  
Wave Heights ◽  
Significant Wave Heights

Abstract Effects of new drag coefficient (Cd) parameterizations on WAVEWATCH III (WW3) model surface wave simulations are investigated. The new parameterizations are based on a coupled wind–wave model (CWW) and a wave tank experiment, and yields reduced Cd at high wind speeds. Numerical experiments for uniform winds and Hurricane Katrina (2005) indicate that the original Cd parameterization used in WW3 overestimates drag at high wind speeds compared to recent observational, theoretical, and numerical modeling results. Comparisons with buoy measurements during Hurricane Katrina demonstrate that WW3 simulations with the new Cd parameterizations yield more accurate significant wave heights compared to simulations with the original Cd parameterization, provided that accurate high-resolution wind forcing fields are used.

Climatic Index of Wind Erosion Conditions in the Great Plains

1963 ◽  
Vol 27 (4) ◽  
pp. 449-452 ◽  
Author(s):  
W. S. Chepil ◽  
F. H. Siddoway ◽  
D. V. Armbrust
Keyword(s):  
Great Plains ◽  
Wind Erosion ◽  
Climatic Index

scholarly journals Upper-Ocean Response to Hurricane Frances (2004) Observed by Profiling EM-APEX Floats*

2011 ◽  
Vol 41 (6) ◽  
pp. 1041-1056 ◽  
Author(s):  
Thomas B. Sanford ◽  
James F. Price ◽  
James B. Girton
Keyword(s):  
Drag Coefficient ◽  
Vertical Mixing ◽  
Ocean Model ◽  
Upper Ocean ◽  
Surface Mixed Layer ◽  
Wind Speeds ◽  
Sst Cooling ◽  
Ocean Response ◽  
Upper Ocean Response ◽  
The Right

Abstract Three autonomous profiling Electromagnetic Autonomous Profiling Explorer (EM-APEX) floats were air deployed one day in advance of the passage of Hurricane Frances (2004) as part of the Coupled Boundary Layer Air–Sea Transfer (CBLAST)-High field experiment. The floats were deliberately deployed at locations on the hurricane track, 55 km to the right of the track, and 110 km to the right of the track. These floats provided profile measurements between 30 and 200 m of in situ temperature, salinity, and horizontal velocity every half hour during the hurricane passage and for several weeks afterward. Some aspects of the observed response were similar at the three locations—the dominance of near-inertial horizontal currents and the phase of these currents—whereas other aspects were different. The largest-amplitude inertial currents were observed at the 55-km site, where SST cooled the most, by about 2.2°C, as the surface mixed layer deepened by about 80 m. Based on the time–depth evolution of the Richardson number and comparisons with a numerical ocean model, it is concluded that SST cooled primarily because of shear-induced vertical mixing that served to bring deeper, cooler water into the surface layer. Surface gravity waves, estimated from the observed high-frequency velocity, reached an estimated 12-m significant wave height at the 55-km site. Along the track, there was lesser amplitude inertial motion and SST cooling, only about 1.2°C, though there was greater upwelling, about 25-m amplitude, and inertial pumping, also about 25-m amplitude. Previously reported numerical simulations of the upper-ocean response are in reasonable agreement with these EM-APEX observations provided that a high wind speed–saturated drag coefficient is used to estimate the wind stress. A direct inference of the drag coefficient CD is drawn from the momentum budget. For wind speeds of 32–47 m s−1, CD ~ 1.4 × 10−3.

Reduced drag coefficient for high wind speeds in tropical cyclones

Nature ◽  
2003 ◽  
Vol 422 (6929) ◽  
pp. 279-283 ◽  
Author(s):  
Mark D. Powell ◽  
Peter J. Vickery ◽  
Timothy A. Reinhold
Keyword(s):  
Drag Coefficient ◽  
Tropical Cyclones ◽  
High Wind ◽  
Wind Speeds

scholarly journals Revisiting the Definition of the Drag Coefficient in the Marine Atmospheric Boundary Layer

2010 ◽  
Vol 40 (10) ◽  
pp. 2325-2332 ◽  
Author(s):  
Richard J. Foreman ◽  
Stefan Emeis
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Atmospheric Boundary Layer ◽  
Drag Coefficient ◽  
Friction Velocity ◽  
Marine Boundary Layer ◽  
Marine Atmospheric Boundary Layer ◽  
Wind Speeds ◽  
Traditional Definition ◽  
Definition Of

Abstract A new functional form of the neutral drag coefficient for moderate to high wind speeds in the marine atmospheric boundary layer for a range of field measurements as reported in the literature is proposed. This new form is found to describe a wide variety of measurements recorded in the open ocean, coast, fetch-limited seas, and lakes, with almost one and the same set of parameters. This is the result of a reanalysis of the definition of the drag coefficient in the marine boundary layer, which finds that a constant is missing from the traditional definition of the drag coefficient. The constant arises because the neutral friction velocity over water surfaces is not directly proportional to the 10-m wind speed, a consequence of the transition to rough flow at low wind speeds. Within the rough flow regime, the neutral friction velocity is linearly dependent on the 10-m wind speed; consequently, within this rough regime, the new definition of the drag coefficient is not a function of the wind speed. The magnitude of the new definition of the neutral drag coefficient represents an upper limit to the magnitude of the traditional definition.

scholarly journals Aerodynamic Properties of Makhobeli, Triticale and Wheat Seeds

2014 ◽  
Vol 28 (3) ◽  
pp. 389-394 ◽  
Author(s):  
Feizollah Shahbazi ◽  
Saman Valizadeh ◽  
Ali Dowlatshah
Keyword(s):  
Moisture Content ◽  
Drag Coefficient ◽  
Terminal Velocity ◽  
Mean Value ◽  
Probability Level ◽  
Mean Values ◽  
Aerodynamic Properties ◽  
The Mean ◽  
Content Range ◽  
Wheat Seeds

Abstract The objective of this study was the evaluation of the aerodynamic properties of Makhobeli, triticale and wheat seeds as a function of moisture content from 7 to 27% (w.b). The results showed that the terminal velocity of triticale and wheat seeds increased linearly from 5.37 to 6.42 and from 6.31 to 8.02 m s-1, respectively, as the moisture content increased from 7 to 27%. Over this same moisture content range, the terminal velocity of Makhobeli seeds varied following a polynomial relationship from 4.52 to 5.07 m s-1. Makhobeli seeds had terminal velocities with a mean value of 4.73 m s-1, at different moisture contents, compared to the mean values of 5.89 and 7.13 m s-1 for triticale and wheat seeds, respectively. The mean value of drag coefficient was 1.12 for Makhobeli compared to the values of 0.92 and 0.85 for triticale and wheat, respectively. The analysis of variance showed that there were significant differences between the terminal velocity (at 1 % probability level) and drag coefficient (at 5% probability level) of Mak-hobeli with triticale and wheat seeds, which suggests that aerodynamic separation of Makhobeli from triticale and wheat is possible.

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