Wind Movement Research Articles

Sibling species distributions of the Simulium damnosum complex in the west African Onchocerciasis Control Programme area during the decade 1984-93, following intensive larviciding since 1974.

During the decade from 1984 to 1993, nine species of the Simulium damnosum complex of blackflies (Diptera: Simuliidae) were identified from the area covered by the Onchocerciasis Control Programme. These were S. damnosum s.s., S. dieguerense, S. konkourense, S. leonense, S. sanctipauli, S. sirbanum, S. soubrense, S. squamosum, and S. yahense. Some of these species were found to consist of two chromosomal variant populations. These were S. konkourense 'Konkouré' and 'Menankaya' forms, S. sanctipauli sensu stricto and 'Djodji' form, S. soubrense 'Chute Milo' and 'Beffa' forms. The distribution of these twelve cytological taxa was assessed in relation to the two main vegetation zones of West Africa (forest and savanna), topography, river size and other factors. The range of each species was influenced by seasonal climatic changes in wind movement and river water level. The most widely distributed species were S. sirbanum and S. damnosum s.s., associated with savanna areas, recorded from all river basins. Simulium dieguerense was restricted mainly to Western Mali on the Rivers Bafing and Bakoye in the Senegal River basin. Simulium squamosum was identified from rivers draining mountainous areas in both the forest and savanna zones. Simulium yahense was found in small permanent rivers along a wide forested band parallel to the coast and was absent from the plains of Togo and Benin. Members of the S. sanctipauli subcomplex had restricted distributions except for S. sanctipauli s.s., which was widespread in large rivers of the forest zone from Sierra Leone to the Volta Lake in Ghana. Simulium soubrense 'Beffa' form occurred in Togo and Benin, S. soubrense 'Chutes Milo' form in Guinea, both 'Konkouré' and 'Menankaya' forms of S. konkourense occurred predominantly in Guinea and S. leonense in Sierra Leone. The relevance of the distribution maps and the importance of the data bank to vector control larvicidal operations are discussed.

Foehns on the Northwestern Slopes of the White Carpathians?

The foehn effect on the northwestern slopes of the White Carpathians has been by many scholars explained as the result of south and souteastern winds. No quantitative-based proofs, however, have so far acknowledged the existence of pseudoadiabatic processes in this region. This article analyses conditions for the rise and movement of foehn-type winds in the Moravian (northwestern) part of the White Carpathians. Data on air temperature and humidity from the period July 1987 - October 1988, recorded at 5 meteorological stations between the Váh and Morava Rivers, have been used.

Efficacy of Foliar Insecticides Against Alfalfa Weevil Larvae, 1997

Abstract Seventeen insecticide treatments and an un-treated check were evaluated against AW in a 4th-year stand of ‘Anstar’ alfalfa located in Floyd Co., VA. Plots of 18 X 20 ft were arranged in a RCBD in each of four replications. AW densities were determined in each plot prior to spray treatment on 15 Apr. Post-treatment AW densities and stem ht were sampled every four to six days in all plots through 13 May. AW density was estimated by collecting and then vigorously shaking 5 stems against the sides of a 5-gal bucket for 10 seconds, then recording the number of small and large AW larvae in the bucket. Stem ht was determined by measuring the length of 2 stems per plot. All insecticide treatments were applied as foliar sprays on 15 Apr using a CO2 backpack sprayer. The backpack sprayer was equipped with 4, 8002VS stainless steel spray tips and calibrated to deliver 20 gpa at 40 psi. Weather conditions during application averaged 51°F air temperature, 63% relative humidity, clear skies, and minimal wind movement. A two-way ANOVA and LSD were used to analyze differences among treatments in AW densities, after (x + 0.5)1/2 transformation, and stem ht.

Efficacy of Foliar Insecticides Against Potato Leafhopper, 1997

Abstract Ten insecticide treatments and an untreated check were evaluated against PLH nymphs and adults in a 4th-year stand of ‘Arrow’ alfalfa located in Montgomery Co., VA. Plots of 20 X 30 ft were arranged in a RCBD in each of four replications. PLH densities and stem ht were determined on 18 Jul in each plot prior to spray treatment. Post-treatment PLH densities and stem ht were sampled every 4 to 5 d in all plots through 11 Aug. PLH density was estimated using combined counts of nymphs and adults from 5 pendulum sweeps of a 15-inch-diam sweep net taken arbitrarily across the plot. Stem ht was determined by measuring the length of 2 stems per plot. All insecticide treatments were applied as foliar sprays on 18 Jul using a CO2 backpack sprayer. The backpack sprayer was equipped with 4, 8002VS stainless steel spray tips and calibrated to deliver 20 gpa at 40 psi. Weather conditions during application ranged from 85-90°F air temperature, clear skies, and minimal wind movement. A two-way ANOVA and LSD were used to analyze differences among treatments in PLH sweep-net counts, after (x + 0.5)1/2 transformation, and stem ht.

Aeolian dynamics in relation to vegetation in a blowout complex in the Meijendel dunes, The Netherlands

Changes in surface elevation in a former blowout in the coastal dunes of Meijendel, The Netherlands, have been monitored almost weekly during one year at 48 erosion pin sites, distributed over 12 units. The units are characterized by specific geomorphological processes. The changes in elevation are caused by wind, slope wash and mass movements. At almost each pin, periods of erosion alternate with periods of accumulation in a random way. Erosion and accumulation sequences are relatively long in areas dominated by aeolian activity, but even here they are randomly distributed. It is the balance between the effects of periods of erosion and periods of accumulation which determines the formation of blowouts or dunes.

Adaptive growth of tree root systems in response to wind action and site conditions.

Soil-root plate dimensions and structural root architecture were examined on 46-year-old Sitka spruce (Picea sitchensis (Bong.) Carr.) trees that had been mechanically uprooted. Rooting depth was restricted by a water table, and root system morphology had adapted to resist the wind movement associated with shallow rooting. The spread of the root system and the ratio of root mass to shoot mass (root/shoot ratio) were both negatively related to soil-root plate depth. Root systems had more structural root mass on the leeward side than the windward side of the tree relative to the prevailing wind direction. Cross sections of structural roots were obtained at distances of 0.5, 0.75, 1.0, and 1.25 m from the tree center. Buttressed parts of roots had greater lateral and vertical secondary thickening above rather than below the biological center. This uneven growth, which produced a shape similar in cross section to a T-beam, was greater on the leeward side of the tree, and was greatest at 0.5 m from the tree center of shallow rooted trees. Further from the tree, particularly on the windward side, many roots developed eccentric cross-sectional shapes comparable to I-beams, which would efficiently resist vertical flexing. Roots became more ovoid in shape with increasing distance from the tree, especially on deep rooted trees where lateral roots tapered rapidly to a small diameter. We conclude that these forms of adaptive growth in response to wind movement improve the rigidity of the soil-root plate and counteract the increasing vulnerability to windthrow as the tree grows.

Aphid Performance in An Alder (Alnus) Hybrid Zone

Population sizes of insect herbivores on natural plant hybrids may be higher, lower, or intermediate to those on the parent species. I studied the biology and population dynamics of a species of free—living aphid (Pterocallis alni) in a hybrid zone of alder (Alnus sp.). The parent trees were Alnus glutinosa and A. incana and their hybrid was A. pubescens. Hybrid trees differed from parents in phenological and morphological characters. Leaf trichome density on hybrid trees was intermediate to trichome densities on A. glutinosa (high density) and A. incana (low density), and thus appeared to be inherited in an additive manner. High trichome density on A. incana resulted in very high mortality and eventual elimination of aphids colonizing this tree. Aphid populations on the hybrid A. pubescens were higher than on A. incana, but lower than on A. glutinosa. However, aphid susceptibility did not appear to be inherited in a strictly additive fashion, as there was a dominance deviation in favor of the susceptible parent. This lack of additivity in insect resistance was most likely due to threshold effect if trichome density, with the density on the hybrid species below the level for the tree to be aphid resistant. Population differences on A. glutinosa and A. pubescens were not caused by differences in growth or reproduction of aphids between hosts. Cage—reared aphids on these two hosts had identical performance in five successive generations. The effect of caging probably reduced wind movement of trichomes and thereby reduced the probability of aphids being dislodged from their feeding site. Predator and parasitoid species responded in a similar manner to the aphids; their numbers were intermediate on the hybrid hosts.

The Flow during TOGA COARE as Diagnosed by the BMRC Tropical Analysis and Prediction System

The evolution of the large-scale flow through the four-month intensive observing period of TOGA COARE is documented from large-scale numerical analyses and GMS cloud imagery produced by the Australian Bureau of Meteorology and transmitted to the field stations during the experiment. The evolution of the flow is dominated by the following phenomena: 1) the normal seasonal evolution of the tropical flow over this region, including a southward and eastward progression of the tropical convective heat source as the Southern Hemisphere monsoon developed and matured; 2) a more eastward than normal progression of this monsoon circulation, associated with a warm event of the ENSO phenomenon; 3) the existence of a major westerly–easterly–westerly cycle of the Madden–Julian low-frequency wave occurring during the latter half of the experimental period, and 4) the development and subsequent movement of tropical cyclones in both (northern and southern) hemispheres. The Madden–Julian event consisted of two eastward progressions across the domain of satellite-observed cloud, south of the equator. The horizontal scale of the cloud regions is approximately 10° latitude × 40° longitude and the eastward phase speed is approximately 3.7 m s−1. Linear correlation studies substantiate the eastward movement of both cloud and zonal wind across the domain. The correlation analysis reveals a strong relationship between cloud and low-level zonal wind, with the cloud variations leading those in wind by approximately five days. Time-longitude sections of relative vorticity show that the synoptic activity also progressed eastward with the cloud, and its structure is suggestive that the controlling dynamics (for the synoptic activity) may be the energy dispersion mechanism of Davidson and Hendon. The development of each westerly event was accompanied by a major change in the Southern Hemisphere deep-layer mean flow from easterly to westerly. Examination of flow fields and satellite imagery for individual days shows that the peak of the first westerly event is associated with the flow patterns surrounding two Southern Hemisphere tropical cyclones. The subsequent rapid evolution to an easterly state occurs as the cyclones move eastward and southward, and the monsoon flow collapses in their wake. There is an accompanying ridging at low levels in the subtropics and the establishment of the Southern Hemisphere subtropical jet. The subsequent reestablishment of the monsoon (the second westerly event) occurs from west to east with the eastward moving cloud bands. There is also a suggestion that an equatorward extension of a Southern Hemisphere upper-level trough may have played a role. Major active and break periods are identified over four tropical subdomains over the TOGA COARE region. These are most easily defined in the Southern Hemisphere subdomains. They are characterized by a slowly ,varying signal in the satellite-observed average cloud-top temperature. Superimposed on this is a rapid transition between the active and break states.

Resistance Mechanisms in RC Building Frames Subjected to Column Failure

There is a damage potential for the columns of building frames due to either unexpected causes such as vehicle impact, boiler explosion, or terrorist attack, or due to design or construction deficiencies aggravated by an earthquake, severe wind, or excessive foundation movement. This paper investigates the redistribution paths of released forces resulting from a column failure and identifies the basic structural defense mechanisms developed in a damaged building frame. Extensive analytical studies revealed that the effect of a column failure is localized to the beams connected to the vertical axis of the failed column and to the adjacent columns. Although the load‐carrying capacity of the connected beams is far exceeded by the redistributed forces, the presence of even light architectural infill walls reduces the beam forces remarkably. It is observed and analytically demonstrated that a partially infilled building frame may survive a base‐column failure without any damage to the other members. Further, i...

Solar and Lunar Daily Geomagnetic Variations

Solar and lunar daily geomagnetic variations provide the basic scientific material for electromagnetic sounding of the Earth at frequencies of 1,2,3,4, cycles per solar or lunar day. The variations also provide information on the upper atmosphere wind movements which give rise to the ionospheric dynamo producing the emf’s driving the current systems. These in turn produce the daily variations.

Inhibition of carbohydrate uptake of Onchocerca volvulus infective larvae (L3) by effector cell constituents.

The in vitro killing of Onchocerca volvulus infective third stage larvae (L3) by components of their human hosts' defence mechanisms is not well documented, as no suitable assay exists. Motility is inappropriate as a criterion of larval viability because of the unsteady winding movements of L3. In the present study, a metabolic parameter for larval viability, the uptake of [3H]2-deoxy-D-glucose, was evaluated. To demonstrate the reproducibility and validity of this test, the oxygen radical hydrogen peroxide (H2O2) was applied to viable L3 and the death of L3 demonstrated by a 90% reduction in glucose uptake. The incorporation of glucose by the filarial larvae was also determined after in vitro exposure to lysates of the putative effector cells, i.e. eosinophilic and neutrophilic granulocytes and monocytes. Effector-cell-derived components led to a 30-80% dose-dependent decrease in deoxy-glucose uptake, with a half-maximal effect at about 500 micrograms ml-1. These experiments demonstrate, for the first time, the deleterious impact of effector cell constituents on the metabolic activity of O. volvulus L3. The assay could be used to evaluate the effect of distinct natural or recombinant effector molecules on the viability of O. volvulus infective larvae and to investigate the effect of parasite molecules which interfere with effector mechanisms.

Bryophytes in perennially moist forests of Papua New Guinea: ecological orientation and predictions of disturbance effects

Water relations of bryophytes must be understood along at least four dimensions: hydration/dehydration frequency; hydration duration; dehydration duration; degree of water loss. All these are biomass-dependent functions such that large colonies of bryophytes may maintain hydration longer than smaller colonies. The spread of a bryophyte colony allows lateral movement of capillary water; contiguous clones will thus allow lateral conduction of that water. In contrast, separated tufts or cushions may store water but will contribute very little to its transfer over the surface of the phorophyte. Many of the tropical rainforests of New Guinea have a larger mass of epiphytic bryophytes than any temperate forest. The primary effect of disturbance in these forests is a reduction in bryomass, presumably due to desiccation because of increased insolation and wind movement. The reduction of bryomass will decrease water and mineral retention in the bryophyte clones; and the reduction in the size of those clones will reduce their contiguity and thus interfere with bryophyte-mediatcd water and mineral transfer. Disturbance may alter bryophyte species frequency but, under present agricultural and forestry practices in New Guinea, I have seen no evidence of significant loss of bryophyte species.

Growth and stomatal responses of sugar maple in irrigated and non-irrigated landfill cover soil

Irrigation increased sugar maple ( Acer saccharum Marsh.) growth and nitrogen content and reduced leaf diffusive resistance on a completed landfill site but not on an adjacent non-landfill control area. Even with irrigation, growth on the landfill was lower than in either the irrigated or non-irrigated control. Lower growth was associated with elevated soil CO 2 concentration and lower O 2 and soil moisture content. The soil gas atmosphere explained variation in leaf diffusive resistance on the landfill plot whereas air temperature, relative humidity and wind movement were correlated with resistance on the control.

INFLUENCE OF WIND ON THE SPRING FLIGHT OF TRYPODENDRON LINEATUM (OLIVIER) (COLEOPTERA: SCOLYTIDAE) IN A SECOND-GROWTH CONIFEROUS FOREST

AbstractA mark–recapture study examined the spring flight dispersal of the ambrosia beetle, Trypodendron lineatum (Olivier), in an even-aged second-growth coastal forest in British Columbia. Pheromone-baited traps were placed in circular traplines at distances from 5 to 500 m from a central release location to (1) examine the relationship between wind direction and beetle catches in traps arranged around the release point, and (2) evaluate beetle catch characteristics when distances to baited traps were varied. A total of 29 800 marked beetles were released in three experiments. Upwind flight was most strongly exhibited at 5 m, with an upwind trend at 25 m, and no consistent flight pattern at 100 m, when wind movement was significantly directed. When the closest attraction was 100 m from the release point, beetles were caught uniformly in all directions indicating that flight was non-directional with respect to wind, for light wind speeds. Catches at 500-m traps tended to be downwind, thus beetles capable of flying that distance were ones that were flying with the wind. Equal numbers of beetles were captured at 5, 25, and 100 m despite increased intertrap spacings of 8, 20, and 32 m, respectively. A higher proportion of beetles were captured at 100 m when close-range traps at 5 and 25 m were not present.

Atmospheric deposition to the edge of a spruce forest in Denmark

Atmospheric deposition was measured during 1 year at the forest edge of a Norway spruce stand in Denmark. Inside the forest the deposition of H +, Ca 2+, Mg 2+, Na +, K +, Cl −, NO 3 −, NH 4 2 and SO 4 2− with canopy throughfall varies with the distance from the forest edge. The deposition at the edge is found to be 10–20 times as high as deposition to an open field and 2–8 times as high as deposition inside the stand. An exponential decrease in deposition as a function of the distance from the forest edge is found. Increased deposition of K + and non-sea salt Mg 2+, which mainly originates as a result of leaching from the needles may be explained by a larger leaf area index (LAI) at the forest edge. Deposition of particulate substances, especially Na +, Cl −, Mg 2+ and to some extent SO 4 2−, NH 4 + and NO 3 − is increased much more than the LAI, which we believe to be caused by changes in wind movements at the forest edge.

Dynamics of Ice-Island Motion Near the Coast of Axel Heiberg Island, Canadian High Arctic

The largest ice island presently known to exist in the Arctic Ocean has a mass of about 700 × 106 tonnes, an area of about 26 km2, and a mean thickness of 42.5 m. Known as Hobson’s Ice Island, this large ice feature has been tracked almost continuously since August 1983 with a succession of Argos buoys. In this paper, two particular ice-island movement episodes near the north-west coast of Axel Heiberg Island are described: 6–16 May 1986 and 14–21 June 1986. Each movement episode is analyzed in terms of the forces acting on the ice island, including wind shear, water drag, water shear, Coriolis force, sea-surface tilt, and pack-ice force. Ice-island movement is generally preceded by an offshore surface wind, and a threshold wind speed of 6 m s°1 appears to be necessary to initiate ice-island motion. An angle of 50° between surface wind and ice-island movement direction is noted during one episode. The pack-ice force, which appears to be the dominant arresting factor of ice-island motion for these two episodes, varies from 100° to 180° to the left of the ice-island velocity direction, depending upon whether the ice island is accelerating or decelerating.

Dynamics of Ice-Island Motion Near the Coast of Axel Heiberg Island, Canadian High Arctic

The largest ice island presently known to exist in the Arctic Ocean has a mass of about 700 × 106 tonnes, an area of about 26 km2, and a mean thickness of 42.5 m. Known as Hobson’s Ice Island, this large ice feature has been tracked almost continuously since August 1983 with a succession of Argos buoys. In this paper, two particular ice-island movement episodes near the north-west coast of Axel Heiberg Island are described: 6–16 May 1986 and 14–21 June 1986. Each movement episode is analyzed in terms of the forces acting on the ice island, including wind shear, water drag, water shear, Coriolis force, sea-surface tilt, and pack-ice force. Ice-island movement is generally preceded by an offshore surface wind, and a threshold wind speed of 6 m s°1 appears to be necessary to initiate ice-island motion. An angle of 50° between surface wind and ice-island movement direction is noted during one episode. The pack-ice force, which appears to be the dominant arresting factor of ice-island motion for these two episodes, varies from 100° to 180° to the left of the ice-island velocity direction, depending upon whether the ice island is accelerating or decelerating.

Influence of Wind on Cotton Growth and Yield

ABSTRACT THE effects of wind on cotton miocroclimate and the concurrent effects on morphology, yield, and water use have not been evaluated. Three wind exposures with three planting dates in 1984 and two wind exposures with two planting dates in 1985 were used to study the interactive effects of wind on cotton growth. The wind shelters consisted of slat fence and slat fence covered with screen wire which reduced the wind movement (0.2 m above the crop) 45% and 55%, respectively. Air temperature and relative humidity 0.2 m above the crop canopy was higher in the sheltered dryland cotton when compared with the unsheltered dryland cotton. Relative humidity above irrigated cotton was not affected by wind. Cotton exposed to wind produced a smaller plant with less leaf area which used less water than sheltered cotton. Sheltered cotton consistently produced more lint than unsheltered cotton for all planting dates and irrigation levels. The average yield increase for sheltered cotton ranged from 2% for the early planted dryland cotton in 1984 to 50% for the late planted irrigated cotton sheltered with screen wire in 1985. Sheltering cotton from wind produced a larger, earlier fruiting plant, which can produce higher yields, under proper environmental and management conditions..

The rainfall movement — A valuable complement to short-term rainfall data

The lack of sufficiently good short-term rainfall data causes errors in runoff simulation in urban areas. The rainfall input traditionally used in urban rainfall-runoff simulation models does not take into account areal and kinematic properties of intensive rainstorms which are relevant in this context. Rainfall data used for runoff simulation may be complemented with rainfall movement parameters, which, in turn, can be calculated from high-altitude wind movement measured at most airports. On examination of ten rainfall events observed in Lund, it is shown that about equally good results in single-event runoff simulations may be obtained using rainfall data from twelve gauges on a 20 km 2 area as when the data from only three gauges complemented with rainfall movement parameters are used. This exemplifies benefits of using rainfall movement as additional information that may favorably complement inadequate rainfall data.

Field evaluation of an acid rain-drought stress interaction

Various methods have been proposed to simulate natural field conditions for growing agricultural crops while controlling conditions to study specific environmental effects. This report briefly describes the use of moveable rain exclusion shelters (10·4 m × 40·9 m) to study the results of the interaction of acid rain and drought stress on corn and soybean yields. The rain exclusion shelters are constructed of galvanized pipe framing and covered with polyethylene film. Movement is automated by a rain switch to protect crops from ambient rainfall and to treat them with simulated acid rain The facility simulates a real environment with respect to variables such as solar exposure, wind movement, dew formation, and insect exposure, while allowing careful control of moisture regimes. Soybeans and corn were treated with average rainfall amounts, and with one-half and one-quarter of these rainfall amounts (drought stress) at two levels of rainfall acidity, pH 5·6 and 3·0. While drought stress resulted in considerable yield reduction for Amsoy and Williams soybeans, no additional reduction in yield was observed with rainfall of pH 3·0, as compared to rainfall of approximately pH 5·6. Similar results were observed for one corn cultivar, Pioneer 3377. For one year of the study however, yield of B73 × Mo17 (corn) was reduced 3139 kg ha −1 by the most severe drought, and an additional 1883 kg ha −1 by acid rain of pH 3·0, as compared to the control (pH 5·6). Yield reduction from acidic rain was considerably less at full water rates, resulting in a significant pH by drought stress interaction. However, during the second year of the experiment, no pH effect or drought by pH interaction was observed for this cultivar. The reason for the difference in the two years was not identified.