Changes In Barometric Pressure Research Articles

Effect of ambient pressure variation on closed loop gas system for India based Neutrino Observatory (INO)

Pilot unit of a closed loop gas mixing and distribution system for the INO project was designed and is being operated with 1.8meters × 1.9meters RPCs for about two years. A number of studies on controlling the flow and optimisation of the gas mixture through the RPC stack were carried out during this period. The gas system essentially measures and attempts to maintain absolute pressure inside the RPC gas volume. During typical Mumbai monsoon seasons, the barometric pressure changes rather rapidly, due to which the gas system fails to maintain the set differential pressure between the ambience and the RPC gas volume. As the safety bubblers on the RPC gas input lines are set to work on fixed pressure differentials, the ambient pressure changes lead to either venting out and thus wasting gas through safety bubblers or over pressuring the RPCs gas volume and thus degrading its performance. The above problem also leads to gas mixture contamination through minute leaks in gas gap.The problem stated above was solved by including the ambient barometric pressure as an input parameter in the closed loop. Using this, it is now possible to maintain any set differential pressure between the ambience and RPC gas volumes between 0 to 20mm of water column, thus always ensuring a positive pressure inside the RPC gas volume with respect to the ambience. This has resulted in improved performance of the gas system by maintaining the constant gas flow and reducing the gas toping up frequency.In this paper, we will highlight the design features and improvements of the closed loop gas system. We will present some of the performance studies and considerations for scaling up the system to be used with the engineering module and then followed by Iron Calorimeter detector (ICAL), which is designed to deploy about 30,000 RPCs of 1.8meters × 1.9 meters in area.

The Association between Airline Flight Time and Sinus Disease

Objectives: Airplane cabin supply air has been shown to have multiple possible respiratory irritants. In addition, changes in barometric pressure in flight may contribute to some respiratory conditions. Therefore, there may be an association between commercial airline flight and sinus disease. Methods: Participants of the Secondhand-Smoke, Air Quality and Respiratory Health Among Flight Attendants study cohort were mailed a questionnaire pertaining to their flight experience and respiratory health. Working years, working days per month, and number of trips per month were quantified, as well as smoking exposure history and self-reported physician diagnoses of sinusitis, asthma, and rhinitis. The sinonasal outcomes were quantified using a Respiratory Questionnaire Score (RQS). Multivariable analyses were performed to analyze the associations between flight time and sinus disease. Results: A total 579 participants met the inclusion criteria, with cohort prevalence of sinusitis, asthma, and rhinitis of 24.8, 13.1, and 20.4%, respectively. There was a significant trend of increasing odds ratios (OR) of sinusitis and rhinitis with increasing working years tertiles ( P < .01 and P = .016, respectively). Increasing tertiles of working days per month were associated with higher RQS scores ( P, trend <.01). Individual symptoms significantly associated with increasing number of working days per month included need to blow nose, sneezing, and thick nasal discharge, among others. Conclusions: This is the first study to analyze the relations between airline flight time and sinonasal disease. Sinusitis diagnosis, numerous sinonasal symptoms, and cumulative symptom scores were all shown to be significantly associated with flight time.

Activity patterns of Gulf Sturgeon (Acipenser oxyrinchus desotoi) in the staging area of the Pascagoula River during fall outmigration

AbstractEnvironmental cues that are associated with individual movement of threatened Gulf Sturgeon from upriver areas to nearshore and offshore winter feeding areas have been described throughout much of their range in the Gulf of Mexico. In this study, we focus on small‐scale movement of Gulf Sturgeon between summer ‘holding’ areas and the fall staging area in the Pascagoula River system (Mississippi, USA). We evaluated a set of logistic regression models using Akaike's Information Criterion and found that relative changes in barometric pressure, time of day, and water temperature were cues for small‐scale Gulf Sturgeon movements during fall outmigration. Numerous environmental cues appear to drive the activity of Gulf Sturgeon in staging areas, indicating the complexity of abiotic factors affecting the observed staging patterns during emigration. The identification of the environmental drivers that are associated with Gulf Sturgeon movement is particularly important if these known saline transition zones change spatially annually with variable rainfall or due to water withdrawals and are used by Gulf Sturgeon making osmotic adjustments while moving downriver.

Impact of changes in barometric pressure on landfill methane emission

AbstractLandfill methane emissions were measured continuously using the eddy covariance method from June to December 2010. The study site was located at the Bluff Road Landfill in Lincoln, Nebraska, USA. Our results show that landfill methane emissions strongly depended on changes in barometric pressure; rising barometric pressure suppressed the emission, while falling barometric pressure enhanced the emission, a phenomenon called barometric pumping. There was up to a 35‐fold variation in day‐to‐day methane emissions due to changes in barometric pressure. Wavelet coherence analysis revealed a strong spectral coherency between variations of barometric pressure and methane emission at periodicities ranging from 1 day to 8 days. Power spectrum and ogive analysis showed that at least 10 days of continuous measurements was needed in order to capture 90% of the total variance in the methane emission time series at our landfill site. From our results, it is clear that point‐in‐time measurements taken at monthly or longer time intervals using techniques such as the trace plume method, the mass balance method, or the closed‐chamber method will be subject to large variations in measured emission rates because of the barometric pumping phenomenon. Estimates of long‐term integrated methane emissions from landfills based on such measurements could yield uncertainties, ranging from 28.8% underestimation to 32.3% overestimation. Our results demonstrate a need for continuous measurements to quantify annual total landfill emissions. This conclusion may apply to the study of methane emissions from wetlands, peatlands, lakes, and other environmental contexts where emissions are from porous media or ebullition. Other implications from the present study for hazard gas monitoring programs are also discussed.

A direct test of the effects of changing atmospheric pressure on the mating behavior of Drosophila melanogaster

Changes in weather can be catastrophic for small insects. As such, it would be highly adaptive for insects to be able to sense when a weather front is approaching and respond appropriately. While correlative and anecdotal evidence exists that flies behav- iorally respond to changes in barometric pressure, which indicate variation in weather, a direct test has yet to be performed. Here, we subject multiple strains of Drosophila mel- anogaster to changes in barometric pressure within a hypobaric chamber and measure male courtship and female receptivity. Since this species has a long copulation duration, cop- ulating when adverse weather is approaching could subject both males and females to potentially lethal conditions. As predicted, some flies reduced their mating activity when exposed to a change in pressure that indicated imminent adverse weather. Surprisingly, however, some flies instead increased their mating activity; the behavioral response depended upon the strain's native population location and intra-population variation, demonstrating that there is genetic variation for the behavioral response. This indicates that flies are able to anticipate weather patterns and change their behavior depending on the barometric pressure they experience, but that the form of behavioral response varies both within and between populations.

An AlN cantilever for a wake-up switch triggered by air pressure change

This research reports an AlN cantilever with an air chamber for a wake-up switch triggered by air pressure change. The proposed sensor is designed to fulfil both high sensitivity and low power consumption. By combining an air chamber to the one side of the AlN cantilever surface, the barometric pressure change generates a piezoelectric voltage. Thus, a wake-up switch triggered by air pressure change can be achieved using an AlN cantilever. The size of the fabricated AlN cantilever was 2000 μm × 1000 μm × 2 μm. The sensitivity to static differential pressure was 11.5 mV/Pa at the range of −20 Pa to 20 Pa. We evaluated the response of the sensor, which was composed of the AlN cantilever and the chamber of 60 ml in volume, when air pressure change was applied. The output voltage increased with increasing the applied air pressure change. It was observed that the maximum output voltage of 50 mV was generated when the air pressure change was 13 Pa.

A portable borehole extensometer and tiltmeter for characterizing aquifers

[1] The solid skeleton of an aquifer moves in response to changes in water pressure, barometric pressure, Earth tides and other factors, and measuring these movements can help characterize aquifers. A device for measuring the vertical displacement and horizontal shear, or tilt, at the same time and place has been developed by combining a tiltmeter and extensometer on a frame that can be temporarily anchored to borehole walls. The device can resolve displacements on the order of 10−8 m and tilts on the order of 10−8 rad. During a 4 h long pumping test in fractured gneiss, the rock contracted by 3 µm in response to 2 m of drawdown, a compliance of roughly 1.5 µm of displacement/meter of head change (1.5 × 10−10 m/Pa). Tilt of 10 s of µrad to the southwest occurred during pumping and both the displacement and the tilt returned during recovery. The tilt signal is repeatable during sequential tests and it changes in magnitude with depth. It can be explained by a fracture zone that strikes roughly EW and dips to the south. Semidiurnal tilts of roughly 0.1 µrad occur during ambient conditions at periods of the O1 and M2 Earth tides. Diurnal displacements of several tens of nanometers are associated with ambient fluctuations in water level when barometric pressure changed by several 100 Pa. Increasing barometric pressure causes water level to fall, but elevates the total pressure in the well. This correlates with dilational displacement, while falling total pressure correlates with contraction during ambient conditions.

Significant infrasound levels a previously unrecognized contaminant in landmark motion sickness studies

Airborne Infrasound at any given point can be accurately described as fluctuations or cyclic changes in the local barometric pressure. Variations in a motion sickness test subject’s elevation result in fluctuations in the surrounding barometric pressure by similar degrees to that experienced on a ship in high seas. Cyclic variation in the lateral or linear velocity of a subject in a vehicle or platform in atmospheric air may also be subject to infrasonic pressure fluctuations due to the Bernoulli principle and possibly vortex shedding effects. Calculations presented demonstrate that in at least one landmark study (McCauley et al., 1976) test subjects were exposed to infrasonic sound pressure levels in excess of 105 db at discrete frequencies between 0.063 and 0.7 Hz. The infrasonic sound pressure level necessarily present in cyclic motion in free atmospheric air does not appear to have been accounted for as a nausea influencing factor in the McCauley et al. (1976) motion sickness studies.

White-throated sparrows adjust behaviour in response to manipulations of barometric pressure and temperature

Correlational evidence suggests that animals may use changes in barometric pressure to predict or respond to changes in weather. Birds adjust the timing of migratory flights and migratory restlessness in response to changing weather, and they make facultative movements in response to storms during winter and breeding. Using the pressure chamber of a hypobaric climatic wind tunnel we tested the responses of white-throated sparrows, Zonotrichia albicollis, to experimental changes in air pressure alone, or air pressure and temperature in combination. Sparrows in wintering (short-day) condition were exposed to gradual changes in pressure/temperature at dawn that simulated large but realistic high- and low-pressure weather systems. During a drop in pressure, birds approached their food cup more quickly and moved more often. There was no effect of increasing pressure and no additional effects of temperature change. Sparrows in spring migratory condition (photostimulated) were exposed to pressure/temperature changes in the evening. Decreases in temperature resulted in less migratory restlessness during the first hour of night, but there was no additional effect of pressure changes. These experimental results indicate that white-throated sparrows can facultatively adjust their behaviour in direct response to changing barometric pressure and temperature.

Environmentally cued parturition in a desert rattlesnake,Crotalus atrox

Embryonic development in animals is dynamically regulated by physiological, behavioural, and environmental factors (temperature, precipitation, humidity), which in turn influence the timing of birth or hatching. In the present study, we provide evidence that parturition in a large-bodied North American pitviper, the western diamond-backed rattlesnake (Crotalus atrox), is environmentally cued. Specifically, we tested the hypothesis of births coinciding with rainfall events during the second-half of the monsoon season (late July to mid September) using randomization modelling. Twenty-one adult females surgically implanted with radio-transmitters were tracked for extended periods from 2001–2010. From 2003 to 2007, the 21 females gave birth to 38 litters, generating sufficient data to test our hypothesis. In all years, births were restricted to a 4-week period from 5 August to 7 September, which spanned between 6 and 19 days (mean ± SD, 15 ± 5.2 days). Most births (92.1%) occurred in August. Births were significantly associated with rainfall events in 2007, although births in 2003 and 2005 occurred closer to rain events than randomly generated births for respective years. However, when birth events across all 5 years were pooled, the model indicated a significance difference in mean rain-days versus random rain-days. Hence, births occurred more closely to rain events than random days. Other variables associated with monsoon events (increases in cloud cover and humidity; changes in barometric pressure) were not measured but constitute potential cues. The present research is the first long-term, individual-based radio-telemetric study of a snake species to investigate environmental cues related to parturition using procedures of randomization modelling. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110, 866–877.

Weather Forecasting by Insects: Modified Sexual Behaviour in Response to Atmospheric Pressure Changes

Prevailing abiotic conditions may positively or negatively impact insects at both the individual and population levels. For example while moderate rainfall and wind velocity may provide conditions that favour development, as well as movement within and between habitats, high winds and heavy rains can significantly decrease life expectancy. There is some evidence that insects adjust their behaviours associated with flight, mating and foraging in response to changes in barometric pressure. We studied changes in different mating behaviours of three taxonomically unrelated insects, the curcurbit beetle, Diabrotica speciosa (Coleoptera), the true armyworm moth, Pseudaletia unipuncta (Lepidoptera) and the potato aphid, Macrosiphum euphorbiae (Hemiptera), when subjected to natural or experimentally manipulated changes in atmospheric pressure. In response to decreasing barometric pressure, male beetles exhibited decreased locomotory activity in a Y-tube olfactometer with female pheromone extracts. However, when placed in close proximity to females, they exhibited reduced courtship sequences and the precopulatory period. Under the same situations, females of the true armyworm and the potato aphid exhibited significantly reduced calling behaviour. Neither the movement of male beetles nor the calling of armyworm females differed between stable and increasing atmospheric pressure conditions. However, in the case of the armyworm there was a significant decrease in the incidence of mating under rising atmospheric conditions, suggesting an effect on male behaviour. When atmospheric pressure rose, very few M. euphorbiae oviparae called. This was similar to the situation observed under decreasing conditions, and consequently very little mating was observed in this species except under stable conditions. All species exhibited behavioural modifications, but there were interspecific differences related to size-related flight ability and the diel periodicity of mating activity. We postulate that the observed behavioral modifications, especially under decreasing barometric pressure would reduce the probability of injury or death under adverse weather conditions.

Frequency of Barodontalgia Among Military or Civilian Pilots and Aircrew Members

Barodontalgia is dental pain triggered by a change in barometric pressure and can be severe enough to cause in-flight incapacitation. There is a large variation of in-flight barodontalgia incidence in the literature and most of the current epidemiological data on barodontalgia has been compiled from military aircrew. The aim of this study was to evaluate the frequency of barodontalgia in French military and civilian aircrew. A cross-sectional study was conducted in 2010. The pilots and crewmembers attending 10 medical units of the French Air Force and Navy, and 5 dedicated to civilian pilots and aircrew were given a standardized and anonymous questionnaire to complete regarding demographic and professional characteristics as well as their barodontalgia. Out of the 1475 questionnaires distributed, 1184 responded (response rate of 80.3%), and 6.6% of these participants (N = 74) reported at least one event of barodontalgia during their career (95% CI: 5.1-8.1%); 43 (6.8%) from the air force and 31 (6.5%) from a civilian service. Median pain intensity during barodontalgia was evaluated at 5.5 out of 10. Pain appeared most commonly during descent (47.3%) and was more frequent below 8000 m. In 10 cases (13.5%), the pilots reported that barodontalgia could have compromised flight security. Despite the improvement of aeronautical equipment and the quality of dental care, barodontalgias were still present in 2010 in the French military and in civilian aircrews. We recommend prevention programs be established in order to minimize the frequency of barodontalgias and their potential repercussions on flight safety.

A barometric pressure sensor based on the air-gap scale effect in a cantilever

The most common structure for a conventional barometric pressure sensor consists of a vacuum-sealed cavity and a diaphragm. However, we hypothesize that a simple structure with an unsealed cavity and an ultra-thin cantilever can provide more sensitive measurements. We produced a 300-nm-thick cantilever with a small spring constant, which made the cantilever sensitive to low pressures. We demonstrated that miniaturizing the air-gap of the cantilever enables the sensor to measure barometric pressure changes at a low pressure change rate with a high resolution, which was 1 Pa at 0.05 Hz, and for a gap size of 1.7 μm.

Limited denitrification in glacial deposit aquifers having thick unsaturated zones (Long Island, USA)

The goal of this study was to demonstrate how the extent of denitrification, which is indirectly related to dissolved organ carbon and directly related to oxygen concentrations, can also be linked to unsaturated-zone thickness, a mappable aquifer property. Groundwater from public supply and monitoring wells in Northport on Long Island, New York state (USA), were analyzed for denitrification reaction progress using dissolved N2/Ar concentrations by membrane inlet mass spectrometry. This technique allows for discernment of small amounts of excess N2, attributable to denitrification. Results show an average 15 % of total nitrogen in the system was denitrified, significantly lower than model predictions of 35 % denitrification. The minimal denitrification is due to low dissolved organic carbon (29.3–41.1 μmol L−1) and high dissolved oxygen concentrations (58–100 % oxygen saturation) in glacial sediments with minimal solid-phase electron donors to drive denitrification. A mechanism is proposed that combines two known processes for aquifer re-aeration in unconsolidated sands with thick (>10 m) unsaturated zones. First, advective flux provides 50 % freshening of pore space oxygen in the upper 2 m due to barometric pressure changes. Then, oxygen diffusion across the water-table boundary occurs due to high volumetric air content in the unsaturated-zone catchment area.

BIRDS STOCK UP AS PRESSURE DROPS

If the weather forecast predicts that a snowstorm is heading your way you'd probably wisely decide to stay snuggled up inside. Wild birds, however, don't have this luxury, and getting caught out in bad weather can have serious consequences. Take for example white crowned sparrows, which return to the snowy mountains of the Sierra Nevada each spring to feast on the insects that have died on the snow. ‘If a storm comes in and snow falls, food availability goes to zero and then the majority of animals will abandon their territories’, says Creagh Breuner, from the University of Montana, USA. But do these storms really take the sparrows by surprise or can they predict them? After being asked this question several times at conferences, Breuner decided to investigate (p. 1982). Breuner explains that it is widely known that birds can sense barometric pressure changes and so she suspected that sparrows could use pressure drops associated with storms as a signal to increase levels of glucocorticoid hormones – stress hormones that divert energy towards maintenance-orientated and preparatory behaviours like feeding.To begin her investigation, Breuner, who has been working out in the Sierra mountains since 1997, looked back over her meticulously kept field notebooks: ‘I know when storms start, I'm out there and I write it down in my notebook – it just started snowing – so I took six snow events and looked to see what happened to barometric pressure before them.’ Sure enough, when she cross-referenced the storms with a dataset from a nearby study of barometric pressure she found that in the 12 h preceding the storm there had been a steady decline in pressure. Having taken between 70 and 100 blood samples each year to measure birds' corticosterone (a glucocorticoid hormone) levels, she was then able to identify samples that had been taken during those 12 h of dropping pressure. However, to her surprise there was no change in corticosterone levels.Although Breuner admits that it was disappointing to see that stress hormone levels did not increase as pressures dropped, she remained undeterred. With the help of two PhD students, Rachel Sprague and Stephen Patterson, Breuner continued her investigation. Back in the lab the team first faced the challenge of how to mimic environmental pressure drops without buying an expensive purpose-built chamber. Breuner turned to her husband and fellow scientist Art Woods for inspiration: ‘Art loves figuring out how to manipulate things that others can't do in the lab, he's just so good electronically and mechanistically with different things’. Woods designed a small Plexiglas chamber with a continuous flow of air through it. He realised that as long as the outflow of air remained constant, he could gradually lower the pressure simply by slowly closing a valve to limit air intake.Just as in the wild, the team found that corticosterone levels didn't increase with declining pressure, but they did find that the birds pecked at their food more. Eating and stocking up on reserves was a clear sign that the birds thought bad weather was on its way. Breuner points out: ‘They can burn through their fat reserves with 24 h of cold weather, so even small increases in fat mass before a storm comes would be an ecologically relevant difference.’ So, whilst the stress hormones don't seem to be the driving force behind their increased appetite and grazing, it is clear that the birds are able to using barometric pressure to predict the weather and as a sign to stock up and prepare for stormy weather ahead.

Does the accuracy of fine-scale water level measurements by vented pressure transducers permit for diurnal evapotranspiration estimation?

Evapotranspiration (ET) estimation methods based on diurnal water level (surface or groundwater) fluctuations are sensitive to measurement accuracy (McLaughlin and Cohen, 2011; Cuevas et al., 2010). Water level fluctuations are often measured by pressure transducers of varying design and precision. Available total pressure transducers require a compensation for barometric pressure change supplied by barometric pressure transducers. Recently McLaughlin and Cohen (2011) as well as Cuevas et al. (2010) analyzed the ‘thermal artifacts’ of such transducer-pair data questioning the applicability of sub-daily water level measurements in non-buffered thermal mode for diurnal ET estimation. Similar problems should not, in principle, occur for so-called vented pressure transducers. With the help of ancillary manual measurements, this study verifies the accuracy of vented pressure transducer obtained ultra-fine scale (temporal resolution of 1–10min) stream- and groundwater level data. Thermal effects were examined by a statistical analysis of concurrent water level and temperature data. The results support the thermal artifact-free nature of vented pressure transducers and therefore their suitability for diurnal ET estimation purposes when proper maintenance and periodic calibrations are provided. In the lack of such measures, diurnal temperature changes can induce errors in vented pressure transducer readings as well.

Operational features, monitoring and control for the RPCs in the ARGO-YBJ experiment

The ARGO-YBJ experiment is a full-coverage array of Resistive Plate Chambers (RPCs) covering a surface of 74 × 78 m2 surrounded by a guard ring. It has been running almost uninterruptedly with its complete layout since November 2007. However, the work to optimize the stability of the experimental setup is still going on. The recorded daily and seasonal changes of temperature and barometric pressure affect the behaviour of the detector, in particular the time resolution and somehow the efficiency. Here a procedure is described for the equalization and the stabilization of the detector response.

Effects of High Altitude on Sleep and Respiratory System and Theirs Adaptations

High-altitude (HA) environments have adverse effects on the normal functioning body of people accustomed to living at low altitudes because of the change in barometric pressure which causes decrease in the amount of oxygen leading to hypobaric hypoxia. Sustained exposure to hypoxia has adverse effects on body weight, muscle structure and exercise capacity, mental functioning, and sleep quality. The most important step of acclimatization is the hyperventilation which is achieved by hypoxic ventilatory response of the peripheral chemoreceptors. Hyperventilation results in increase in arterial carbondioxide concentration. Altitude also affects sleep and cardiac output, which is the other determinant of oxygen delivery. Upon initial exposure to HA, the resting pulse rate increases rapidly, but with acclimatization, heart rate and cardiac output tend to fall. Another important component that leads to decrease in cardiac output is the reduction in the stroke volume with acclimatization. During sleep at HA, the levels of CO2 in the blood can drop very low and this can switch off the drive to breathe. Only after the body senses a further drop in O2 levels breathing is started again. Periodic breathing is thought to result from instability in the control system through the hypoxic drive or the response to CO2.

Magnetoreception and baroreception in birds

The world as we know it is defined by our senses, although as humans we are equipped to receive and interpret only a fraction of the potential sensory information available. Birds have evolved with different sensory priorities to our own; they can use the Earth's magnetic field as a navigational aid, and are sensitive to slight changes in barometric pressure. These abilities help explain the impressive ability of many bird species to orientate, navigate, and maintain steady altitude during flight over long distances, even in the absence of clear visual cues. This review will explore the history of research into these "avian" senses, highlighting their likely mechanisms of action, underlying neuronal circuitry and evolutionary origins.

Removing barometric pressure effects from groundwater level and identifying main influential constituents

Changes in barometric pressure can affect the micro-dynamic state of groundwater level. The groundwater level data carry a lot of important information of tectonic activity and earthquakes. It is very significant to eliminate the barometric pressure effects from the groundwater level data in order to recognize seismic anomalies effectively. With the analysis of the main influential constituents of barometric pressure and their changes, we can have a better understanding of the changes of the aquifer medium, which can provide useful information for earthquake prediction. Taking the May 12, 2008 Wenchuan earthquake as an example, this paper deals with the influence of barometric pressure on groundwater level based on observational data from Nanxi, Qionglai and Chaohu wells. The methods of the linear regression and the deconvolution regression were employed to remove the barometric pressure from the groundwater level data. The harmonic analysis and the spectral analysis were used to recognize the main influential waves of barometric pressure effect. A comparison was conducted on the main influential waves before and after the earthquake. The results showed that the main influential waves of barometric pressure effect changed and the amplitudes of all constituents also changed. This phenomenon may result from the characteristics of the influential constituents of pressure, or from the changes of the aquifer medium, which were caused by the earthquake.