Drag coefficient and plant form response to wind speed in three plant species: Burning Bush (Euonymus alatus), Colorado Blue Spruce (Picea pungensglauca.), and Fountain Grass (Pennisetum setaceum)

2002 ◽  
Vol 107 (D24) ◽  
Author(s):  
J. A. Gillies
Keyword(s):  
Wind Speed ◽  
Drag Coefficient ◽  
Plant Species ◽  
Euonymus Alatus ◽  
Blue Spruce ◽  
Pennisetum Setaceum ◽  
Plant Form

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 Phenology of Petersianthus Macrocarpus from 2017 to 2020 and Risk of Pollinosis in Dictrict of Abidjan

2020 ◽  
Vol 3 (2) ◽  
Keyword(s):  
High Risk ◽  
Wind Speed ◽  
Plant Species ◽  
Cote D'ivoire ◽  
Côte D’Ivoire ◽  
Pollen Calendar ◽  
Floral Phenology ◽  
Flowering Periods ◽  
The Impact ◽  
Number Of Individuals

Petersianthus macrocarpus is a plant species whose pollens are potentially allergenic. This plant is present from the coast to the centre of the country. The objective of this study is to prevent populations from being exposed to the pollens of Petersianthus macrocarpus. Specifically, it was a question of defining the flowering of Petersianthus macrocarpus, evaluating the impact of the climate on this flowering and listing the populations most exposed to P. macrocarpus pollens. The study took place in Abidjan, in the commune of Yopougon, specifically in South Niangon, from September 2017 to June 2020. Sampling by quadrat allowed to determine the number of individuals, the cover, the density and the frequency of the vegetation. Floral phenology was carried out by weekly observations using binoculars. The coverage in each quadrat was 1 and the frequency 100%. Individuals less than 6 m high did not bear any flowers. Two flowering periods were observed in the years 2017 to 2019. The first was from April to June, the second from November to January. However, there was no flowering from April to June in 2020. The evolution of rainfall in 2020 was not identical to that of the three previous years. The phenology of Petersianthus macrocarpus presents periods of high risk of pollinosis and is influenced by rainfall. Increasing wind speed exposes new populations to pollen. The installation of pollen collectors is certainly necessary to establish the pollen calendar of Petersianthus macrocarpus in Côte d’Ivoire.

scholarly journals Assessment of the Potential of Introduction, Establishment and Further Spread of Invasive Alien Plant Species of European Union Concern in Lithuania

Botanica ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 37-48 ◽  
Author(s):  
Zigmantas Gudžinskas ◽  
Egidijus Žalneravičius ◽  
Lukas Petrulaitis
Keyword(s):  
Invasive Species ◽  
European Union ◽  
Plant Species ◽  
Alien Plant Species ◽  
Myriophyllum Aquaticum ◽  
Impatiens Glandulifera ◽  
Alien Plant ◽  
Invasive Alien Plant ◽  
Heracleum Mantegazzianum ◽  
Pennisetum Setaceum

AbstractThe list of invasive alien species of European Union concern currently includes 23 plant species. The aim of this study was to assess the potential and importance of introduction pathways for invasive alien plant species in Lithuania, to estimate probability of their establishment and further spread in the country. Analysis of all available information revealed that three species (Asclepias syriaca,Heracleum sosnowskyiandImpatiens glandulifera) currently occur in Lithuania and the latter two are widespread invasive species in the country. The remaining 20 plant species have not been registered in the wild in Lithuania so far. Four of these,Gunnera tinctoria,Lysichiton americanus,Myriophyllum aquaticumandPennisetum setaceum, are occasionally cultivated in gardens or other outdoor areas, and six species, e.g.Cabomba caroliniana,Eichhornia crassipes, Lagarosiphon major, are cultivated in aquaria or other indoor spaces. Naturalization of seven species is unlikely in the country, whereas naturalization of 13 species (Lysichiton americanus,Myriophyllum aquaticum,Pennisetum setaceum, etc.) is plausible. Five of the analysed and still not recorded species are recognized as potentially invasive in Lithuania; the invasion of five species is plausible and that of 10 species is unlikely. The most important pathway of introduction of the analysed species is ornamental gardening. Three species that have not been recorded in Lithuania, but occur in the neighbouring regions of Europe (Elodea nuttallii,Heracleum mantegazzianum,Heracleum persicum) can enter the country by natural means. Importance of permanent studies and surveys on alien plants aiming to ensure early detection and eradication of invasive species is discussed.

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.

Non-monotonous dependence of the ocean surface drag coefficient on the hurricane wind speed due to the fragmentation of the ocean-atmosphere interface

2017 ◽  
Vol 477 (1) ◽  
pp. 1373-1378 ◽  
Author(s):  
Yu. I. Troitskaya ◽  
O. S. Ermakova ◽  
A. A. Kandaurov ◽  
D. S. Kozlov ◽  
D. A. Sergeev ◽  
...  
Keyword(s):  
Wind Speed ◽  
Drag Coefficient ◽  
Ocean Surface ◽  
Surface Drag ◽  
Hurricane Wind ◽  
Ocean Atmosphere

scholarly journals On the Linear Parameterization of Drag Coefficient over Sea Surface

2004 ◽  
Vol 34 (12) ◽  
pp. 2847-2851 ◽  
Author(s):  
Changlong Guan ◽  
Lian Xie
Keyword(s):  
Wind Speed ◽  
Drag Coefficient ◽  
Linear Function ◽  
Sea Surface ◽  
Wave Steepness ◽  
Wave Age ◽  
Age Dependent ◽  
Logarithmic Law ◽  
Linear Parameterization ◽  
Charnock Relation

Abstract Combining the logarithmic law with the Charnock relation yields a drag coefficient that is a function of wind speed with the Charnock coefficient as a parameter. It is found that the function is nearly linear within the typically measured range of the drag coefficient. The slope of the linear function is dominated by the Charnock coefficient. When the Charnock relation is extended to a wave age–dependent function, the drag coefficient remains a near-linear function of wind speed after invoking the 3/2 power law. The slope of the linear function is dominated by wave steepness.

scholarly journals 811 PB 196 FOLIAR VARIATIONS IN FALL COLOR DEVELOPMENT AMONG FIVE PLANT SPECIES

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 549d-549
Author(s):  
Suman Singha ◽  
Bernard Bible ◽  
Edward Corbett
Keyword(s):  
Plant Species ◽  
Acer Saccharum ◽  
Acer Rubrum ◽  
Significant Loss ◽  
Euonymus Alatus ◽  
Color Changes ◽  
Color Development ◽  
Red Color ◽  
Marked Location ◽  
Red Coloration

Variations in the pattern of fall color development in the leaves of Acer rubrum, Acer saccharum, Quercus coccinea, Oxydendrum arboreum and Euonymus alatus were determined. CIELAB coordinates were measured with a Minolta CR-2000b calorimeter at a marked location on 5 tagged leaves from 2 plants of each species. The changes in hue follow similar trends in these species, but the time of onset varies. Onset of red color development increased variability in hue between leaves of the same species. Based on color changes in E. alatus anthocyanin development occurs prior to significant loss of chlorophyll and red coloration remains masked, whereas in A. rubrum anthocyanin development occurs in association with or following the loss of chlorophyll. This results in differences in the pattern of hue and chroma development between these species.

scholarly journals Aerodynamic Characteristics Over Fine-Grained Gravel Surfaces in a Wind Tunnel

2021 ◽  
Vol 9 ◽  
Author(s):  
Jiaqi Liu ◽  
Reiji Kimura ◽  
Jing Wu
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Drag Coefficient ◽  
Lower Layer ◽  
Aerodynamic Characteristics ◽  
Gobi Desert ◽  
Near Surface ◽  
Fine Grained ◽  
Wind Speeds ◽  
Speed Fluctuations

Gravels can protect soil from wind erosion, however, there is little known about the effects of fine-grained gravel on aerodynamic characteristics of the near-surface airflow. Drag coefficient, wind-speed gradient, and turbulent transfer coefficient over different coverages of gravel surfaces were investigated in a compact boundary-layer wind tunnel. The drag coefficient of the fine-grained gravel surface reached the maximum value at 15% coverage and then tended to stabilize at gravel coverage 20% and greater. At a height of 4 cm, near-surface airflow on gravel surfaces can be divided clearly into upper and lower sublayers, defined as the inertial and roughness sublayers, respectively. The coefficient of variation of wind speed over gravel surfaces in the roughness sublayer was 8.6 times that in the inertial sublayer, indicating a greater effect of gravel coverage on wind-speed fluctuations in the lower layer. At a height of 4 cm, wind-speed fluctuations under the observed wind speeds were independent of changes in gravel coverage. In addition, an energy-exchange region, where sand particles can absorb more energy from the surrounding airflow, was found between the roughness and inertial sublayers, enhancing the erosional state of wind-blown sand. This finding can be applied to evaluate the aerodynamic stability of the gravel surface in the Gobi Desert and provide a theoretical basis for elucidation of the vertical distributions of wind-blown sand flux.

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