The effect of row orientation on below-canopy turbulence characteristics in a wine-vineyard

2020 ◽  
Author(s):  
Nurit Agam ◽  
Yasmin Levi ◽  
Joe Alfieri ◽  
John Prueger
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Momentum Flux ◽  
Power Spectra ◽  
Prevailing Wind ◽  
High Momentum ◽  
Turbulence Characteristics ◽  
Grape Quality ◽  
Sonic Anemometers ◽  
Prevailing Wind Direction

<p>The momentum flux affects the energy exchange processes and thus may indirectly affect the water balance of agricultural fields. In wine vineyards, a high momentum flux between the vine rows may augment the evaporation and transpiration fluxes, and therefore decrease the water use efficiency. On the other hand, at night, high momentum fluxes may reduce (or even prevent) the formation of dew on the vine canopy, thus decrease the potential development of fungi and related diseases. We hypothesized that the wind direction relative to the row orientation in largely-spaced narrow hedge-rows characterizing wine vineyards greatly affects the turbulent structure and the momentum flux. This, in turn affects the vineyard microclimate, and ultimately, the grape quality. The objective of our research was to explore the effect of wine-vineyard row orientation on wind and temperature profiles below (and slightly above) the canopy and on the turbulence characteristics and eddy size.  The research was conducted in two adjacent vineyards in the Judean foothills in Israel (31°48'38.6"N 34°50'43.6"E and 31°48'37.1"N 34°50'24.0"E) having row orientations of NE-SW and SE-NW, respectively. With a NW prevailing wind direction, the wind is typically flowing perpendicularly to the former and in parallel to the latter. In each vineyard, 10 self-made type-T fine-wire thermocouples (0.08 mm diameter) were set on a pole places in the middle of the inter row, at heights above the ground of 5, 10, 20, 40, 80, 140, 220, 250, 300, and 400 cm. In addition, 4 fast-response 2D sonic anemometers were set at 10, 40, 140, and 250 cm above the ground. The measurements were conducted at 20 Hz.  Below canopy wind regime differed with orientation, mostly at heights lower than 2.5m. Higher wind speed below the canopy and smaller wind speed gradients were observed at the vineyard parallel to the prevailing wind direction.  Temperature gradients were mostly larger in the vineyard perpendicular to the prevailing wind direction.  Nevertheless, the power spectra were generally more uniform in height at the perpendicular vineyard.  </p>

scholarly journals Spatiotemporal Characteristics of Near-Surface Wind in Shenzhen

2020 ◽  
Vol 12 (2) ◽  
pp. 739 ◽  
Author(s):  
Cheng Liu ◽  
Qinglan Li ◽  
Wei Zhao ◽  
Yuqing Wang ◽  
Riaz Ali ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Surface Wind ◽  
Prevailing Wind ◽  
Average Wind Speed ◽  
Near Surface ◽  
Average Wind ◽  
Prevailing Wind Direction ◽  
Seasonal Wind ◽  
The Mean

The spatiotemporal characteristics of near-surface wind in Shenzhen were investigated in this study by using hourly observations at 92 automatic weather stations (AWSs) from 2009 to 2018. The results show that during the past 10 years, most of the stations showed a decreasing trend in the annual mean of the 10 min average wind speed (avg-wind) and the mean of the 3 s average wind speed (gust wind). Over half of the decreasing trends at the stations were statistically significant (p < 0.05). Seasonally, the decrease in wind speed was the most severe in spring, followed by autumn, winter, and summer. The distribution of wind speed tends to be greater in the east and coastal areas for both avg-wind and gust wind. From September to March of the following year, the prevailing wind direction in Shenzhen was northerly, and from April to August, the prevailing wind direction was southerly. The seasonal wind speed distribution exhibited two different types, spring–summer type and autumn–winter type, which may be induced by their different prevailing wind directions. The analysis by the empirical orthogonal function (EOF) method confirmed the previous findings that the mean wind speed was decreasing in Shenzhen and that two different seasonal wind speed spatial distribution patterns existed. Such a study could provide references for wind forecasting and risk assessment in the study area.

Wind analysis at Ganja International Airport

2020 ◽  
Vol 61 (12) ◽  
pp. 162-165
Author(s):  
Ulker Faig Bayramova ◽  
Keyword(s):  
Wind Speed ◽  
Key Words ◽  
Wind Direction ◽  
Maximum Speed ◽  
Prevailing Wind ◽  
Wind Rose ◽  
International Airport ◽  
Wind Analysis ◽  
Prevailing Wind Direction ◽  
The Mean

The article reviews wind conditions at Ganja International Airport and specifies the maximum winds observed during the month and the direction of the winds. The direction of the mean, maximum wind speed of the prevailing wind was analyzed. Based on our analysis, we can see that the prevailing wind direction isnortheast and the maximum speed was recorded in March. Key words: wind, temperature, aviation, wind rose, visibility

scholarly journals Caracterização da Velocidade e Direção do Vento em Mossoró/RN (Characterization of Wind Speed and Direction in Mossoró/RN)

2014 ◽  
Vol 7 (4) ◽  
pp. 746
Author(s):  
Giuliana Mairana de Morais ◽  
José Espínola Sobrinho ◽  
Wesley De Oliveira Santos ◽  
Danielly De Oliveira Costa ◽  
Saulo Tasso Araújo da Silva ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Agricultural Activities ◽  
Prevailing Wind ◽  
Average Wind Speed ◽  
Average Wind ◽  
Prevailing Wind Direction ◽  
Automatic Station ◽  
Semi Arid

O vento é de grande importância para muitas atividades humanas, especialmente para as atividades agropecuárias. O objetivo desse trabalho foi caracterizar a velocidade e a direção predominante do vento para Mossoró/RN, no período de janeiro de 2000 a dezembro de 2012. Foram analisados dados da velocidade média do vento a 10 m e 2 m de altura e direção predominante do vento para o período de 24 horas. Os dados foram coletados por uma Estação Meteorológica Automática, localizada na UFERSA (Universidade Federal Rural do Semi-Árido), em Mossoró/RN. Os valores da velocidade média do vento tendem a aumentar no segundo semestre do ano, tendo uma queda nos seus valores no primeiro semestre. Os valores médios de velocidade do vento para o período estudado foram de 3,32 m s-1 para 10 m e de 2,30 m s-1 para 2 m de altura, já as velocidades máximas instantânea do período estudado foram de 13,04 m s-1 para 10 m e de 9,40 m s-1 para 2 m de altura. A direção predominante do vento ficou na maioria dos meses entre sudeste (SE) e leste (E).   ABSTRACT The wind is of great importance to many human activities, especially for agricultural activities. The aim of this study was to characterize the speed and direction of the prevailing wind to Mossoró/RN, from January 2000 to December 2012. The datas from the average wind speed at 10 m and 2 m in height and the prevailing wind direction for the period of 24 hours. Data were collected by an Automatic Weather Station, located in UFERSA (Federal Rural University of the Semi - Arid), in Mossoró/RN. The values of average wind speed tend to increase in the second half of the year, with a fall in values in the first half. The average wind speed for the study period were 3.32 m s-1 to 10 m and 2.30 m s-1 to 2 m high, since the instantaneous speeds of the study period were 13.04 m s-1 to 10 m and 9.40 m s-1 to 2 m in height. The predominant wind direction was in most months between southeast (SE) and east (E).   Keywords: Climate, Anemometer, Automatic Station. 

scholarly journals Evaluating multi-year, multi-site data on the energy balance closure of eddy-covariance flux measurements at cropland sites in southwestern Germany

2019 ◽  
Vol 16 (2) ◽  
pp. 521-540 ◽  
Author(s):  
Ravshan Eshonkulov ◽  
Arne Poyda ◽  
Joachim Ingwersen ◽  
Hans-Dieter Wizemann ◽  
Tobias K. D. Weber ◽  
...  
Keyword(s):  
Energy Balance ◽  
Eddy Covariance ◽  
Wind Direction ◽  
Climate Models ◽  
Global Climate Models ◽  
Energy Balance Closure ◽  
Prevailing Wind ◽  
Atmospheric Conditions ◽  
Prevailing Wind Direction ◽  
Wide Range

Abstract. The energy balance of eddy-covariance (EC) measurements is typically not closed, resulting in one of the main challenges in evaluating and interpreting EC flux data. Energy balance closure (EBC) is crucial for validating and improving regional and global climate models. To investigate the nature of the gap in EBC for agroecosystems, we analyzed EC measurements from two climatically contrasting regions (Kraichgau – KR – and Swabian Jura – SJ) in southwestern Germany. Data were taken at six fully equipped EC sites from 2010 to 2017. The gap in EBC was quantified by ordinary linear regression, relating the energy balance ratio (EBR), calculated as the quotient of turbulent fluxes and available energy, to the residual energy term. In order to examine potential reasons for differences in EBC, we compared the EBC under varying environmental conditions and investigated a wide range of possible controls. Overall, the variation in EBC was found to be higher during winter than summer. Moreover, we determined that the site had a statistically significant effect on EBC but no significant effect on either crop or region (KR vs SJ). The time-variable footprints of all EC stations were estimated based on data measured in 2015, complimented by micro-topographic analyses along the prevailing wind direction. The smallest mean annual energy balance gap was 17 % in KR and 13 % in SJ. Highest EBRs were mostly found for winds from the prevailing wind direction. The spread of EBRs distinctly narrowed under unstable atmospheric conditions, strong buoyancy, and high friction velocities. Smaller footprint areas led to better EBC due to increasing homogeneity. Flow distortions caused by the back head of the anemometer negatively affected EBC during corresponding wind conditions.

scholarly journals The Occurrences and Formation of Ladderback Ripples on Barchans Dunes of Najaf Dunes Field, Iraq, in Aeolian Environments

2021 ◽  
pp. 1598-1604
Author(s):  
Ahmed Jawad Al-Naji ◽  
Hasan Kattoof Jasim ◽  
Mazin Y. Tamar-Agha ◽  
Thamer Abaas Al-Shammery
Keyword(s):  
Wind Direction ◽  
Prevailing Wind ◽  
Fine Grained ◽  
Prevailing Wind Direction ◽  
Barchan Dunes ◽  
Light Mineral ◽  
Sand Sediments

This paper concerns the study of ripples that occur on the windward of Barchan dunes from the dunes field of Najaf governorate, Iraq. These dunes consist mainly of sand sediments with variable sizes, including medium, fine, and very fine sands. Quartz represents the major light mineral in the Najaf Dunes sand. The prevailing wind direction in the study area is NW-SE. The major ripple crest series of every pattern are oriented perpendicular to the NW-SE wind direction, whereas imbricated ripple groups within the troughs of the preexisting ripples are created by the WSW-ENE wind trend. These ripples tend to be formed by shortened ripples that occupy the troughs of the prolonged series. All crests of the ladderback ripples are oriented at right angles to asymmetry ripples. The ladderback ripples were noticed from fine to very fine- grained sediments, which consist mainly of quartz. The wavelength of the ladderback ripples ranges from 2 – 4 cm, while they are 0.1 – 0.2 cm in height. The occurrence of ladderback ripples within an aeolian environment indicates a variety of wind directions, which influenced the arrangements of the crest ripples.

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