Adverse Weather Effects Research Articles

Phenology of spring migration of Wood Sandpiper Tringa glareola through Europe

Phenology and dynamics of spring migration of the Wood Sandpiper through Europe was analysed, using both literature and new field data collected at five wetlands in Central Europe (N Poland and S Belarus). The passage through all Europe lasted from mid-March until end of June and at the five Central European sites between mid-April and end of May. Migration was very concentrated (50% of migrants during 6–10 days), and median dates at all Central European sites were between 3 and 15 May. Regression of mean peak dates on latitude of the sites showed that spring migration through Europe was quick, about 97 km/day. In most years passage had one peak, but two peaks in some seasons at eastern sites may reflect passage of migrants using a SE route or be an effect of adverse weather. Migration intensity varied among seasons. This may have been caused by changes of water levels or other habitat components. Tight timing of spring passage suggests that in Central Europe the Wood Sandpiper adopt a time-minimising migration strategy.

Weather-Responsive Signal Timing

This paper presents a systematic investigation into the effects of adverse weather on signal operation and the potential benefits of implementing weather-responsive signal control. The investigation considered isolated and coordinated signalized intersections in urban and suburban areas under various traffic conditions. Both operational and safety analyses were conducted in this investigation. Traffic signal optimization and microscopic traffic simulation were used to perform the operational analysis with average travel time as a performance measure. The safety analysis used the adequacy of change and clearance intervals and the presence of dilemma zones as indicators of safety at signalized intersections. Study results suggest that operational benefits of weather-responsive signal control are generally significant and that the greatest benefits can be realized at coordinated corridors in town and city centers. Results also suggest that dilemma zones are most likely introduced on a particular intersection approach once the coefficient of friction between tire and pavement drops below the design value of a wet pavement. Further, a set of recommended guidelines that relate weather conditions to operational impacts and potential benefits of weather-responsive signal timing was developed and provided in this study.

Weather-Responsive Signal Timing: Practical Guidelines

This paper presents a systematic investigation into the effects of adverse weather on signal operation and the potential benefits of implementing weather-responsive signal control. The investigation considered isolated and coordinated signalized intersections in urban and suburban areas under various traffic conditions. Both operational and safety analyses were conducted in this investigation. Traffic signal optimization and microscopic traffic simulation were used to perform the operational analysis with average travel time as a performance measure. The safety analysis used the adequacy of change and clearance intervals and the presence of dilemma zones as indicators of safety at signalized intersections. Study results suggest that operational benefits of weather-responsive signal control are generally significant and that the greatest benefits can be realized at coordinated corridors in town and city centers. Results also suggest that dilemma zones are most likely introduced on a particular intersection approach once the coefficient of friction between tire and pavement drops below the design value of a wet pavement. Further, a set of recommended guidelines that relate weather conditions to operational impacts and potential benefits of weather-responsive signal timing was developed and provided in this study.

Economic and financial position of agricultural enterprises in the period before the accession to the European Union

In the year before the accession to the European Union, the Slovak agricultural sector reported a loss of SKK 2.4 billion and following a profitable year, the earnings were reduced by SKK 2.8 billion. The situation was caused by a number of reasons, namely reduced sales of agricultural products, damage resulting from adverse weather effects (cold weather, hail, drought and  swine fever), as well as widening of the price gap compared to the year before (increasing input prices in agriculture and decreasing purchase prices of agricultural products, especially in livestock production). Legal entities and natural persons experienced mixed business success. While 51% of legal entities made profit, the figure rose to 76% in the group of natural persons. Both the agricultural cooperatives and trading companies performed with a loss. The loss per hectare of agricultural land (a.l.) was substantially lower in the case of business companies. Natural persons - private farmers were profitable over the period. The gap between the profitable and loss-making enterprises has widened. Some 60% of profitable enterprises owned by legal entities made only a small profit below SKK 0.5 million. The loss-making performance was typical for more productive areas of Slovakia. This was related to stronger effects of adverse climate in 2003.

Effect of adverse weather on the voltage dip mitigation capability of a static transfer switch

AbstractThis paper discusses the effect of time‐varying failure rates due to adverse weather on the voltage dip mitigation capability of a static transfer switch (STS). A model that takes into account the increase in both failure rate and repair time due to adverse weather is proposed. Applicabilty of the model and additional effort needed in collecting data are discussed. Sensitivity of the model to uncertainties in the data is assessed.

Modeling the Economic Impact of Adverse Weather into En Route Flights

A methodology is presented to quantify and minimize the effect of adverse weather on commercial and general aviation traffic. The method described uses two simple models, the Air Traffic Flow Model and the Adverse Weather Impact Model, to quantify the impact of adverse weather into regional airspace operations in the National Airspace System (NAS). The impact of adverse weather in aviation in system delays is well documented. Weather is a major source of delays in NAS. In the past 5 years, weather has accounted for 71.2% of all delays in NAS according to statistics compiled and published by the FAA. Adverse weather varies in extent from a few square miles to thousands of square miles. Besides causing delays, it affects the safety, comfort, and efficiency of aviation. Better models to manage air traffic under adverse weather conditions are needed. Ultimately, these models could be deployed as decision-support systems to aid air traffic personnel to divert traffic optimally in a real-time scenario.

Temperature and mortality in 11 cities of the eastern United States.

Episodes of extremely hot or cold temperatures are associated with increased mortality. Time-series analyses show an association between temperature and mortality across a range of less extreme temperatures. In this paper, the authors describe the temperature-mortality association for 11 large eastern US cities in 1973-1994 by estimating the relative risks of mortality using log-linear regression analysis for time-series data and by exploring city characteristics associated with variations in this temperature-mortality relation. Current and recent days' temperatures were the weather components most strongly predictive of mortality, and mortality risk generally decreased as temperature increased from the coldest days to a certain threshold temperature, which varied by latitude, above which mortality risk increased as temperature increased. The authors also found a strong association of the temperature-mortality relation with latitude, with a greater effect of colder temperatures on mortality risk in more-southern cities and of warmer temperatures in more-northern cities. The percentage of households with air conditioners in the south and heaters in the north, which serve as indicators of socioeconomic status of the city population, also predicted weather-related mortality. The model developed in this analysis is potentially useful for projecting the consequences of climate-change scenarios and offering insights into susceptibility to the adverse effects of weather.

Effects of adverse weather and aging on power system reliability

Most power system reliability studies assume a constant failure rate and an exponentially distributed repair time. For redundant (parallel) components, using the average component failure rates gives erroneous results. The effect of time-varying failure rates is discussed for adverse weather and for component aging. A primary-selective supply is used to introduce the phenomena. In particular, adverse weather is shown to significantly affect the interruption frequency. Both adverse weather and component aging require additional data collection efforts. Including component aging also requires a serious modeling effort.

Increases in Moose, Caribou, and Wolves Following Wolf Control in Alaska

Short-term studies in our study area and southeast Yukon have previously documented substantial increases in moose (Alces alces) and caribou (Rangifer tarandus) following wolf (Canis lupus) control. To provide long-term information, we present a 20-year history beginning autumn 1975 when precontrol wolf density was 14 wolves/1,000 km 2 . Private harvest and agency control kept the late-winter wolf density 55-80% (x = 69%) below the precontrol density during each of the next 7 years. Wolf numbers subsequently recovered in ≤ 4 years in most of the study area and increased further to between 15 and 16 wolves/1,000 km 2 during a period of deep snowfall winters. The post-hunt moose population increased rapidly from 183 to 481 moose/1,000 km 2 during the 7 years of wolf control (finite rate of increase, λ r = 1.15) and increased more slowly during the subsequent 12 years (λ r = 1.05) reaching a density of 1,020 moose/1,000 km 2 by 1994. The Delta caribou herd increased rapidly during wolf control (λ r = 1.16), more slowly during the subsequent 7 years (λ r = 1.06), then declined for 4 years (X r = 0.78) from a peak density of 890 caribou/ 1,000 km 2 . This decline coincided with declines in 2 adjacent, low-density herds (240-370 caribou/1,000 km 2 ). These caribou declines probably resulted from the synergistic effects of adverse weather and associated increases in wolf numbers. Reduced caribou natality and calf weights were associated with adverse weather. Wolf control was reauthorized to halt the Delta herd's decline in 1993. Similar subarctic, noncoastal systems without effective wolf control have supported densities of 45-417 moose/l,000 km 2 (x = 148, n = 20), 100-500 caribou/1,000 km 2 , and 2-18 wolves/1,000 km 2 (x = 9, n = 15) in recent decades. In our 20-year history, 7 initial winters of wolf control and 14 initial years of favorable weather apparently resulted in 19 years of growth in moose, 14 years of growth in caribou populations, and a high average autumn wolf density after control ended (12 wolves/1,000 km 2 ). Benefits to humans included enjoyment of more wolves, moose, and caribou and harvests of several thousand additional moose and caribou than predicted if wolf control had not occurred. We conclude from historical data that controlling wolf populations, in combination with favorable weather, can enhance long-term abundance of wolves and their primary prey, and benefits to humans can be substantial.

Effect of roadway geometrics and environmental factors on rural freeway accident frequencies

This paper explores the frequency of occurrence of highway accidents on the basis of a multivariate analysis of roadway geometrics (e.g. horizontal and vertical alignments), weather, and other seasonal effects. Based on accident data collected in the field, a negative binomial model of overall accident frequencies is estimated along with models of the frequency of specific accident types. Interactions between weather and geometric variables are proposed as part of the model specifications. The results of the analysis uncover important determinants of accident frequency. By studying the relationship between weather and geometric elements, this paper offers insight into potential measures to counter the adverse effects of weather on highway sections with challenging geometrics.

Effect of forage matting on rate of grass drying, rate of silage fermentation, silage intake and digestibility of silage by sheep

AbstractThe effects of forage matting on rate of grass drying and silage fermentation, digestibility, and intake were examined using perennial ryegrass swards. Treatments compared were: forage mats, where grass was processed through a laboratory scale macerator prior to matting and wilting to 228 g dry matter (DM) kg−1 (FM treatment); unconditioned grass which was direct ensiled at 163 g DM kg−1 (DE treatment); unconditioned grass which was wilted for the same period as FM to 213 g DM kg−1 (UC treatment); unconditioned grass which was wilted to 234 g DM kg−1 (UC25, treatment). All forages were dried on black plastic sheeting. For each treatment a total of approximately 80 kg grass DM was ensiled in seven 290 I plastic bins for 136 d prior to feeding to wether sheep. A further total of 14 kg grass DM from each treatment was ensiled in twenty‐one plastic pipes (152 mm diameter, 762 mm long) to give a total of 84 pipes. Rate of silage fermentation was determined by destructively sampling pipes following 1, 2, 4, 6, 13, 20 and 50 d of ensilage. Over the mean wilting period of 6·9 h, grass from the FM treatment dried significantly faster (P < 0·001) and required less solar energy per unit of moisture loss than unconditioned grass. The rate of grass drying was highly correlated with solar radiation. The FM treatment did not influence the rate or extent of silage fermentation. The intakes and digestibilities of FM, UC and UC25 were not significantly (P < 0·05) different from each other but were higher than for the DE treatment (P < 0·05 for digestibility and NS for intake). In Northern Ireland it is unlikely that there will be sufficient solar radiation to allow forage mats to be made, wilted to a level to prevent effluent production and harvested within one working day. Further work is required to optimize mat‐making technology for more rapid drying and to determine the effect of adverse weather on nutrient losses from mats.

Dynamics of an Introduced Caribou Population

Caribou (Rangifer tarandus groenlandicus) were hunted to extinction on Southampton Island (Northwest Territories, Canada) by 1953. In 1967, 48 caribou were captured on neighbouring Coats Island and released on Southampton Island. We documented the population dynamics, group size and composition, and distribution of caribou from introduction to 1991, based on aerial and ground survey data. The number of one-year-old caribou grew from 38 in 1967 to 13 700 (SE = 1600) in 1991. The corresponding annual growth rate was 27.6%, with no indication of any decline in the rate with increasing population density. Contrary to models describing the irruption of ungulates, the population dispersed rapidly after introduction to use all suitable habitats. Southampton caribou did not show high winter mortality in some years as did caribou on neighbouring Coats Island, where caribou density was higher, suggesting that the effect of adverse weather on the dynamics of northern insular caribou populations is dependent on animal density.Key words: caribou, Rangifer, population dynamics, irruption, distribution, Northwest Territories

Radiation transmission in adverse weather

A simplified practical approach to determining the effects of weather on the transmission of radiation at visible, infrared (IR), and millimetre (mm) wavelengths, with particular reference to the aircraft landing problem, is outlined. Passive landing systems are studied. Landing categories related to visibility are defined. An extinction coefficient used to relate the effect of the atmosphere on the radiation detected by the human eye (or an imaging sensor onboard the aircraft) to the landing category and the calculation of this coefficient are discussed. The approach makes use of data from openly available literature. Results have been found useful in indicating the effects of adverse weather on imaging sensor performance for an enhanced vision aircraft-mounted landing system. As an example of the technique, the method of determining the extinction coefficients in fog for infrared radiation is outlined. >

Opposing effects of spring defoliation on late season oak caterpillars

ABSTRACT. 1. The pedunculate oak, Quercus rohur L., suffers high annual levels of spring defoliation in Wytham Woods. near Oxford.2. This spring defoliation affects late season caterpillars through a variety of damage‐induced changes in the leaves.3. Diurnea fagella (D. & S.), one of the commonest late season caterpillars, shows reduced larval survival and pupal weight on regrowth foliage when compared to undamaged primary foliage.4. D. fagella also suffer higher larval mortality on naturally damaged primary foliage than they do on undamaged foliage.5. Despite this, the three commonest late season caterpillar species are more abundant on damaged trees than undamaged ones. and their distributions are biased towards damaged leaves within the canopy.6. Other factors that may be more important than leaf damage in determining the distribution and abundance of late season caterpillars are discussed. D.fagella larvae spin their larval refuges more rapidly on damaged than undamaged foliage, and this may reduce mortality by natural enemies, or ameliorate adverse effects of weather.

Effect of adverse weather on neonatal caribou survival — a review

This paper reviews the relationship between adverse weather and neonatal caribou (Rangifer tarandus spp.) survival in North America by examining the available literature and our own findings. The viewpoint that adverse weather on the calving ground can result in major losses of newborn barren-ground caribou (R. t. groenlandicus) calves is largely unsupported. Published reports of calf mortality caused by adverse weather are questionable because causes of death were rarely determined by postmortem examinations. Circumstantial evidence associated with the small samples of dead calves does not support published assumptions that the mortality was weather related, or that high losses due to adverse weather are common events. The applicability of results from physiological testing are questionable, because the calves were restrained and the behaviour of unrestrained animals was ignored in the conclusions drawn from the tests. The relationship between adverse weather and calf mortality is more speculation than documentation yet often has been uncritically cited. In our view, healthy newborn barren-ground caribou are well adapted physiologically and behaviourally to cope with all but the most severe adverse weather.

A combat aircraft mission readiness model

It has always been important for military commanders to be able to rely on their equipment being available to them during a conflict. Some recent published figures, however, showed that two modern fighter aircraft were only available for missions for 47% or 56% of the time.A simple operation simulation model was derived to show an aircraft's sensitivity to the main availability parameters. This model can be applied to any aircraft type provided that the necessary inputs can be calculated. The simulated operations were as realistic as possible, although many assumptions had to be made.For reasons of national security it was not possible to relate this study directly to any current service aircraft, so a design project study has been used as the baseline aircraft in the simulation model. This aircraft was the 1980 Mini-CAS, developed at Cranfield Institute of Technology. This was used because all the necessary data were available or could be estimated with reasonable confidence and also the operating conditions are comparable to a number of current service types employed in the Close-Air-Support role. Thus the simulation was kept realistic and the results and conclusions are directly applicable to real and projected designs. Subsequent work checked the validity of the model by simulating an A-10 exercise and Sea Harrier operations in the Falklands conflict.The Operations Simulation Model proved to be a satisfactory means of assessing the effectiveness of a force of aircraft under war-time conditions. It was far more flexible than the Availability and Mission Readiness equations commonly used to compare the in-service performance of aircraft and highlighted areas where resources could best be concentrated to improve availability. Further improvements are necessary however, to take account of spares shortages and the effect of adverse weather.

Transmission Line Reliability Models Including Common mode and Adverse Weather Effects

This paper illustrates the developrrent ard analysis of a group of transmission system nodels which include both corn mode failures and adverse weather conditions. Both of these factors have been considered as separate phencxrenon in previously developed nodels and as such have been subjected to individual and independent analysis. The nodels illustrated in this paper are used to examine the sensitivity of selected reliability indices to individual paraneter variation in the composite model.

Transmission Line Reliability Models Including Common Mode and Adverse Weather Effects

Transmission Line Reliability Models Including Common Mode and Adverse Weather Effects

Weather and the Success of Parasites in Population Regulation

AbstractExamples and data based on the host-parasite complex of the California red scale, Aonidiella aurantii (Maskell), and its parasites in untreated test plots in the citrus areas of southern California, not including the San Joaquin Valley and the desert areas, show the following: (1) Weather does not impose upper limits to host population increase. (2) In areas of favorable weather, certain parasites regulate host population densities at very low levels, other factors also being favorable. (3) The parasite Aphytis lingnanensis Compere is affected by weather differentially with respect to the host, and to varying degrees in different localities. The effects of field weather for each 2-week period of the year on all stages of this parasite individually as well as on population growth in held experimental cages are discussed. Adverse effects of weather on the parasite preclude successful population regulation of the host by the parasite at certain times or in particular areas but the range of the parasite is not restricted. (4) Another parasite, Comperiella bifasciata Howard, has its range restricted by weather and not by competition with other parasites to intermediate and interior citrus growing areas. It is never found along the coast. (5) Yet another parasite, Prospaltella perniciosi Tower, has its range restricted by competition and not by weather although it gives the appearance of being restricted by weather because it occurs only in coastal districts. (6) Examples are discussed of interactions between weather and dust, ants, or chemicals with parasites and hosts which result in various modifications of the abundance of the host and parasites. (7) Examples are discussed of the effect of weather on interactions between competing species of parasites and the host which have resulted in striking modifications of the previous distribution of certain parasites.