Effect of windbreaks on wind speed reduction and soil protection against wind erosion

Windbreaks form efficient soil protection against wind erosion particularly at the time when soil cover is not protected by the cultivated plant vegetation cover. The objective of this research was to evaluate windbreaks efficiency in terms of wind speed reduction. Wind speed along the windbreaks was measured in the cadastral areas of Dobrovíz and Středokluky (Czech Republic, Central Europe). The measurement was carried out by 4 stations placed at windward side (1 station at the distance of 3 times the height of the windbreak) and at leeward side of the windbreak (3 stations at the distance of 3, 6, and 9 times the height of the windbreak). Each station contained 2 anemometers situated 0.5 and 1 m above surface. The character of windbreak was described by terrestrial photogrammetry method as the value of optical porosity from the photo documentation of the windbreak at the time of field measurement. A significant dependence between the value of optical porosity and efficiency of windbreak emerged from the results. The correlation coefficient between optical porosity and wind speed reduction was in the range of 0.842 to 0.936 (statistical significance more than 95%). A significant effect of windbreak on airflow reduction was proven on the leeward side of windbreak in a belt corresponding to approximately six times the height of the windbreaks depending on the optical porosity and it was expressed by a polynomial equation.

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The character of windbreaks and their influence on mitigation of soil erosion

Glasnik Sumarskog fakulteta ◽

10.2298/gsf1614219r ◽

2016 ◽

pp. 219-226 ◽

Cited By ~ 1

Author(s):

David Řehácek ◽

Tomás Khel ◽

Josef Kucera ◽

Jan Vopravil ◽

Martin Petera

Keyword(s):

Wind Speed ◽

Soil Cover ◽

Leeward Side ◽

Soil Protection ◽

Speed Reduction ◽

Speed Measurement ◽

Ambulatory Measurement ◽

Optical Porosity ◽

Cultivated Plant ◽

Wind Speed Measurement

Windbreaks create efficient soil protection against wind erosion particularly at the time when soil cover is not protected by vegetation cover of cultivated plant. The objective of this research was to find correlation between qualitative parameters of windbreaks and their efficiency in terms of wind speed reduction. The wind speed measurement was carried out by 4 stations along windbreak. The station contains 2 anemometers at heights 0.5 and 1 m above the surface. The character of windbreak was described by photogrammetry method as the value of optical porosity from the photo documentation of the windbreak at the time of ambulatory measurement. Important dependency between the value of optical porosity and efficiency of windbreak emerged from the results. An important protective effect of windbreak on soil was proven on the leeward side of the windbreak in the belt corresponding with approximately six times the height of the windbreaks.

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The efficiency of windbreaks on the basis of wind field and optical porosity measurement

Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis ◽

10.11118/actaun200856040281 ◽

2008 ◽

Vol 56 (4) ◽

pp. 281-288 ◽

Cited By ~ 6

Author(s):

Tomáš Středa ◽

Petra Malenová ◽

Hana Pokladníková ◽

Jaroslav Rožnovský

Keyword(s):

Wind Speed ◽

Wind Field ◽

Close Relation ◽

Horizontal Wind ◽

Leeward Side ◽

Profile Measurement ◽

Average Wind Speed ◽

Speed Reduction ◽

Average Wind ◽

Optical Porosity

Windbreaks have been used for many years to reduce wind speed as a wind-erosion control measure. To assessment of windbreak efficiency two main parameters are using: height of windbreak (H) and aerodynamic porosity. In South Moravian Region the total area of windbreaks is approximately 1200 ha. For purposes of horizontal profile measurement of wind speed and wind direction windbreaks with various spices composition, age and construction in cadastral territory Suchá Loz and Micmanice were chosen. Windbreak influence on horizontal wind profile was found out in distance of 50, 100, 150 and 200 m in front and behind windbreak in two-meter height above surface. For the optical porosity measurement the ImageTool program was used. The wind field measurement results of windbreak in Suchá Loz cadastral shows limited effect of windbreak on wind speed. The windbreak is created mainly by Canadian poplars (Populus × canadensis). In dependence on main species foliage stage the effect of windbreak was obvious on leeward side to distance of 100–150 m (c. 5–7 H). Average optical porosity of windbreak in Suchá Loz was 50% (April). Reduction of average wind speed was about 17% maximally in this stage. Optical porosity was 20% and wind speed reduction was about 37% during second measurement (October). The second monitored windbreak (Micmanice) had a significant influence on wind speed even to the maximal measured distance (200 m, c. 14 H). This windbreak created mainly by Acer sp. and Fraxinus excelsior reduced the wind speed about 64%. During first measurement (May) the optical porosity of 20% and maximal wind speed reduction of 64% were assessed. For optical porosity of 21% (October) the wind speed reduction was about 55%. Close relation between optical porosity and wind speed reduction was found out by statistical evaluation. Correlation coefficient regardless locality for distance of 50 m was −0.80, 100 m −0.92, 150 m −0.76 and for distance of 200 m −0.63.

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2.5D Flexible Wind Sensor Using Differential Plate Capacitors

Sensors ◽

10.3390/s21093101 ◽

2021 ◽

Vol 21 (9) ◽

pp. 3101

Author(s):

Yu Wan ◽

Zhenxiang Yi

Keyword(s):

Wind Speed ◽

Wind Direction ◽

Parallel Plate ◽

Electrode Array ◽

Copper Electrode ◽

Windward Side ◽

Leeward Side ◽

Electrode Layer ◽

Young’S Moduli ◽

Speed Up

In this paper, a novel 2.5-dimensional (2.5D) flexible wind sensor is proposed based on four differential plate capacitors. This design consists of a windward pillar, two electrode layers, and a support layer, which are all made of polydimethylsiloxane (PDMS) with different Young’s moduli. A 2 mm × 2 mm copper electrode array is located on each electrode layer, forming four parallel plate capacitors as the sensitive elements. The wind in the xy-plane tilts the windward pillar, decreasing two capacitances on the windward side and increasing two capacitances on the leeward side. The wind in the z-axis depresses the windward pillar, resulting in an increase of all four capacitances. Experiments demonstrate that this sensor can measure the wind speed up to 23.9 m/s and the wind direction over the full 360° range of the xy-plane. The sensitivities of wind speed are close to 4 fF·m−1·s and 3 fF·m−1·s in the xy-plane and z-axis, respectively.

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Impact of coastal East Antarctic ice rises on surface mass balance: insights from observations and modelling

10.5194/egusphere-egu2020-20370 ◽

2020 ◽

Author(s):

Thore Kausch ◽

Stef Lhermitte ◽

Jan T.M. Lenaerts ◽

Nander Wever ◽

Mana Inoue ◽

...

Keyword(s):

Mass Balance ◽

Wind Erosion ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

Windward Side ◽

Leeward Side ◽

Surface Mass Balance ◽

Surface Mass ◽

Local Erosion

About 20% of all snow accumulation in Antarctica occurs on the ice shelfs and ice rises, locations within the ice shelf where the ice is locally grounded on topography. These ice rises largely control the spatial surface mass balance (SMB) distribution by inducing snowfall variability due to orographic uplift and by inducing wind erosion due altering the wind conditions. Moreover these ice rises buttress the ice flow and represent an ideal drilling locations for ice cores.In this study we assess the connection between snowfall variability and wind erosion to provide a better understanding of how ice rises impact SMB variability, how well this is captured in the regional atmospheric climate model RACMO, and the implications of this SMB variability for ice rises as an ice core drilling side. By combining ground penetrating radar profiles from two ice rises in Dronning Maud Land with ice core dating we reconstruct spatial and temporal SMB variations across both ice rises from 1982 to 2017. Subsequently, the observed SMB is compared with output from RACMO, SnowModel to quantify the contribution of the different processes that control the spatial SMB variability across the ice rises. Finally, the observed SMB is compared with Sentinel-1 backscatter data to extrapolate spatial SMB trends over larger areas.Our results show snowfall-driven differences of up to ~ 0.24 m w.e./yr between the windward and the leeward side of both ice rises as well as a local erosion driven minimum at the peak of the ice rises. RACMO captures the snowfall-driven differences, but overestimates their magnitude, whereas the erosion on the peak can be reproduced by SnowModel with RACMO forcing. Observed temporal variability of the average SMBs calculated for 4 time intervals in the 1982-2017 range are low at the peak of the easternmost ice rise (~ 0.03 m w.e./yr), while being three times higher (~ 0.1 m w.e./yr) on the windward side of the ice rise. This implicates that at the peak of the ice rise, higher snowfall, driven by regional processes, such as orographic uplift, is balanced out by local erosion. &#160;Comparison of the observed SMB gradients with Sentinel-1 data finally shows the potential of SAR satellite observations to represent spatial variability in SMB across ice shelves and ice rises.

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Windbreak and airflow performance of different synthetic shrub designs based on wind tunnel experiments

PLoS ONE ◽

10.1371/journal.pone.0244213 ◽

2020 ◽

Vol 15 (12) ◽

pp. e0244213

Author(s):

Xia Pan ◽

Zhenyi Wang ◽

Yong Gao ◽

Zhengcai Zhang ◽

Zhongjv Meng ◽

...

Keyword(s):

Wind Speed ◽

Wind Tunnel ◽

Wind Erosion ◽

Protective Effects ◽

Wind Tunnel Experiments ◽

Speed Reduction ◽

Environmental Threats ◽

Wind Speeds ◽

Airflow Field ◽

Reduction Effect

Wind erosion has gained increasing attention as one of the most serious global ecological and environmental threats. Windbreaks are effective at decreasing wind erosion by reducing wind speed to protect crops, livestock, and farmsteads, while providing wildlife habitats. Synthetic shrubs can act as novel windbreaks; however, there is limited knowledge on how their design affects wind speed. This study determined the protective effects (airflow field and sheltering efficiency) based on the design of synthetic shrubs in a wind tunnel. Broom-shaped synthetic shrubs weakened the wind speeds mainly at the middle and upper parts of the shrubs (5–14 cm), while for hemisphere-shaped shrubs this effect was greatest near their bases (below 4 cm) and least in the middle and upper parts (7–14 cm). Spindle-shaped synthetic shrubs provided the best reduction effect in wind range and strength. Moreover, the wind speed reduction ratio decreased with improved wind speeds and ranged from 26.25 cm (between the second and third rows) to 52.5 cm (after the third row). These results provide strong evidence that synthetic shrubs should be considered to decrease wind speed and prevent wind erosion.

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Development and application of a street-level meteorology and pollutant tracking system (S-TRACK)

10.5194/acp-2021-725 ◽

2021 ◽

Author(s):

Huan Zhang ◽

Sunling Gong ◽

Lei Zhang ◽

Jianjun He ◽

Yaqiang Wang ◽

...

Keyword(s):

Air Pollution ◽

Wind Speed ◽

Line Source ◽

Living Environment ◽

Windward Side ◽

Leeward Side ◽

Street Level ◽

Building Layout ◽

Potential Impact ◽

Traffic Source

Abstract. A multi-model simulation system for street level circulation and pollutant tracking (S-TRACK) has been developed by integrating the Weather Research and Forecasting (WRF), the Computational Fluid Dynamics (CFD) and the Flexible Particle (FLEXPART) models. The winter wind environmental characteristics and the potential impact of a traffic source on nearby sites (about 300 to 400 m) in Jinshui district of Zhengzhou, China are analyzed with the system. It is found that the existence of buildings complicates the structure of the wind fields. The wind speed inside the building block is smaller than the background wind speed due to the dragging effect of dense buildings. Ventilation is better when the dominant airflow is in the same direction as the building layout. Influenced by the building layout, local circulations show that the windward side of the building is mostly the divergence zone and the leeward side is mostly the convergence zone, which is more obvious for high buildings and influencing air pollution transport at the street-level. Using the traffic source (line source) on a road within a city block, the system was applied to investigate the potential impact of a line source on specific sites under the influence of the streel-level circulations. The potential contribution ratio was estimated by the method of residence time analysis and to a particular site found to vary with the height of the site with a peak not at the ground but on a certain height. The results of the study are helpful to understand the characteristics of wind environment and effect of traffic emissions in the area, which is important to improve urban living environment and control air pollution.

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Impact of coastal East Antarctic ice rises on surface mass balance: insights from observations and modeling

The Cryosphere ◽

10.5194/tc-14-3367-2020 ◽

2020 ◽

Vol 14 (10) ◽

pp. 3367-3380

Author(s):

Thore Kausch ◽

Stef Lhermitte ◽

Jan T. M. Lenaerts ◽

Nander Wever ◽

Mana Inoue ◽

...

Keyword(s):

Mass Balance ◽

Wind Erosion ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

Windward Side ◽

Leeward Side ◽

Surface Mass Balance ◽

Surface Mass ◽

Local Erosion

Abstract. About 20 % of all snow accumulation in Antarctica occurs on the ice shelves. There, ice rises control the spatial surface mass balance (SMB) distribution by inducing snowfall variability and wind erosion due to their topography. Moreover these ice rises buttress the ice flow and represent ideal drilling locations for ice cores. In this study we assess the connection between snowfall variability and wind erosion to provide a better understanding of how ice rises impact SMB variability, how well this is captured in the regional atmospheric climate model RACMO2 and the implications of this SMB variability for ice rises as an ice core drilling site. By combining ground-penetrating radar (GPR) profiles from two ice rises in Dronning Maud Land with ice core dating, we reconstruct spatial and temporal SMB variations from 1983 to 2018 and compare the observed SMB with output from RACMO2 and SnowModel. Our results show snowfall-driven differences of up to 1.5 times higher SMB on the windward side of both ice rises than on the leeward side as well as a local erosion-driven minimum at the ice divide of the ice rises. RACMO2 captures the snowfall-driven differences but overestimates their magnitude, whereas the erosion on the peak can be reproduced by SnowModel with RACMO2 forcing. Observed temporal variability of the average SMBs, retrieved from the GPR data for four time intervals in the 1983–2018 range, are low at the peak of the easternmost ice rise (∼0.06 mw.e.yr-1), while they are higher (∼0.09 mw.e.yr-1) on the windward side of the ice rise. This implies that at the peak of the ice rise, higher snowfall, driven by orographic uplift, is balanced out by local erosion. As a consequence of this, the SMB recovered from the ice core matches the SMB from the GPR at the peak of the ice rise but not at the windward side of the ice rise, suggesting that the SMB signal is damped in the ice core.

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Impact of coastal East Antarctic ice rises on surface mass balance: insights from observations and modeling

10.5194/tc-2020-66 ◽

2020 ◽

Author(s):

Thore Kausch ◽

Stef Lhermitte ◽

Jan T. M. Lenaerts ◽

Nander Wever ◽

Mana Inoue ◽

...

Keyword(s):

Mass Balance ◽

Wind Erosion ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

Windward Side ◽

Leeward Side ◽

Surface Mass Balance ◽

Surface Mass ◽

Local Erosion

Abstract. About 20 % of all snow accumulation in Antarctica occurs on the ice shelves. There, ice rises control the spatial surface mass balance (SMB) distribution by inducing snowfall variability and wind erosion due to their topography. Moreover these ice rises buttress the ice flow and represent ideal drilling locations for ice cores. In this study we assess the connection between snowfall variability and wind erosion to provide a better understanding of how ice rises impact SMB variability, how well this is captured in the regional atmospheric climate model RACMO2, and the implications of this SMB variability for ice rises as an ice core drilling site. By combining ground penetrating radar (GPR) profiles from two ice rises in Dronning Maud Land with ice core dating we reconstruct spatial and temporal SMB variations from 1982 to 2017 and compare the observed SMB with output from RACMO2 and SnowModel. Our results show snowfall driven differences of up to 1.5 times higher SMB on the windward side of both ice rises than on the leeward side, as well as a local erosion driven minimum at the ice divide of the ice rises. RACMO2 captures the snowfall driven differences, but overestimates their magnitude, whereas the erosion on the peak can be reproduced by SnowModel with RACMO2 forcing. Observed temporal variability of the average SMBs, retrieved from the GPR data for four time intervals in the 1982–2017 range, are low at the peak of the easternmost ice rise (~ 0.03 m w.e./yr), while being three times higher (~ 0.1 m w.e./yr) on the windward side of the ice rise. This implies that at the peak of the ice rise, higher snowfall, driven by orographic uplift, is balanced out by local erosion. As a consequence of this the SMB recovered from the ice core matches the SMB from the GPR at the peak of the ice rise, but not at the windward side of the ice rise, suggesting that the SMB signal is dampened in the ice core.

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Study on Heat Exchange of Different Ventilation Structures of Asynchronous Traction Motor for High Speed EMU

Transportation systems and technology ◽

10.17816/transsyst20195216-30 ◽

2019 ◽

Vol 5 (2) ◽

pp. 16-30

Author(s):

Weili Li ◽

Junci Cao ◽

Dong Li ◽

Zhigang Wu

Keyword(s):

Temperature Distribution ◽

Wind Speed ◽

High Speed ◽

Heat Dissipation ◽

Windward Side ◽

Maximum Temperature ◽

Leeward Side ◽

Stator Core ◽

Traction Motor ◽

Asynchronous Traction Motor

Background: Aiming at the problems of high local temperature and uneven temperature distribution in asynchronous traction motor of high-speed Electric Multiple Unit (EMU) when it is running. Aim: In this paper, the influence of ventilation system with different structure on temperature distribution is studied. Methods: Taking 600kW asynchronous traction motor as an example, the electromagnetic-fluid-temperature analysis model of the traction motor is established, and the temperature values of different positions in the motor are obtained. The accuracy of the calculation results is verified by comparing with the actual measurement. On this basis, by adjusting the structure of stator and rotor axial ventilation holes, the relationship between temperature distribution and fluid flow state in motor is studied. In addition, the influence of fluid incidence angle on fluid velocity and heat dissipation performance of motor is also studied, and the ventilation structure scheme with relative balance of axial and circumferential temperature in motor is found out, which provides a reference strategy for the design of temperature rise of motor with forced ventilation structure. Results: The wind speed near the intake side of stator teeth and rotor teeth groove is less than that far from the intake side. The flow distribution trend of rotor vent is similar to that of stator vent, but the air in the groove is affected by centrifugal force of rotor rotation, which makes the wind speed difference on the intake side larger than that on the outlet side. The stator winding and rotor guide bar are affected by wind temperature to reach the maximum temperature at the end of the outlet respectively. The stator core is higher at the windward side and the leeward side than the other parts of the motor. The heat dissipation effect at both ends is good. The highest temperature of the stator core appears near the leeward side.

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