Effect Of Barometric Pressure Research Articles

The effect of atmospheric pressure on CH4 and CO2 emission from a closed landfill site in Manchester, UK

A time series study was conducted to ascertain the effect of barometric pressure on the variability of CH4 and CO2 concentrations in a closed landfill site. An in situ data of methane/carbon dioxide concentrations and environmental parameters were collected by means of an in-borehole gas monitor, the GasClam (Ion Science, UK). Linear regression analysis was used to determine the strength of the correlation between ground-gas concentrations and barometric pressure. The result shows CH4 and CO2 concentrations to be variable with weak negative correlations of 0.2691 and 0.2773, respectively, with barometric pressure over the entire monitoring period. Although the R(2) was slightly improved by considering their concentration over single periods of rising and falling pressure, single periods of rising pressure and single periods of falling pressure, their correlations remained insignificant at 95% confidence level. The result revealed that atmospheric pressure--the acclaimed major control on the variability of ground-gas concentration--is not always so. A case was made for the determination of other possible controls such as changes in temperature, soil permeability, landfill water depth, season, and geology of the borehole and also how much of control each factor would have on the variability/migration of CH4 and CO2 concentrations from the studied landfill.

Lowering barometric pressure aggravates depression-like behavior in rats

Weather change has been known to influence the condition of patients with mood disorder. However, no animal studies have tested the influence of climatic factor on emotional impairment. In this study, we examined the effect of lowering barometric pressure (LP) in a climate-controlled room on immobility time in the forced swim test in rats, which is considered to be an index of behavioral despair (helplessness). When the rats were exposed to daily repeated forced swim, the immobility time gradually increased. This increment was inhibited by repeated administration of the antidepressant imipramine, suggesting that the immobility is an anxiety/depression-like behavior. LP exposure (20hPa below the natural atmospheric pressure) further increased immobility time in rats submitted to repeated forced swim. In another series of experiments, we examined the effect of daily repeated LP exposure on the maintenance of immobility after withdrawal from 6-day repeated forced swim. When the rats were challenged with forced swim under natural atmospheric pressure on day 14 after the withdrawal, immobility time was significantly longer than in non-conditioned rats. These findings demonstrated that LP in the range of natural weather change augmented the depression-like behavior in rats.

Hydroecological factors governing surface water flow on a low‐gradient floodplain

Interrelationships between hydrology and aquatic ecosystems are better understood in streams and rivers compared to their surrounding floodplains. Our goal was to characterize the hydrology of the Everglades ridge and slough floodplain ecosystem, which is valued for the comparatively high biodiversity and connectivity of its parallel‐drainage features but which has been degraded over the past century in response to flow reductions associated with flood control. We measured flow velocity, water depth, and wind velocity continuously for 3 years in an area of the Everglades with well‐preserved parallel‐drainage features (i.e., 200‐m wide sloughs interspersed with slightly higher elevation and more densely vegetated ridges). Mean daily flow velocity averaged 0.32 cm s−1 and ranged between 0.02 and 0.79 cm s−1. Highest sustained velocities were associated with flow pulses caused by water releases from upstream hydraulic control structures that increased flow velocity by a factor of 2–3 on the floodplain for weeks at a time. The highest instantaneous measurements of flow velocity were associated with the passage of Hurricane Wilma in 2005 when the inverse barometric pressure effect increased flow velocity up to 5 cm s−1 for several hours. Time‐averaged flow velocities were 29% greater in sloughs compared to ridges because of marginally higher vegetative drag in ridges compared to sloughs, which contributed modestly (relative to greater water depth and flow duration in sloughs compared to ridges) to the predominant fraction (86%) of total discharge through the landscape occurring in sloughs. Univariate scaling relationships developed from theory of flow through vegetation, and our field data indicated that flow velocity increases with the square of water surface slope and the fourth power of stem diameter, decreases in direct proportion with increasing frontal area of vegetation, and is unrelated to water depth except for the influence that water depth has in controlling the submergence height of vegetation that varies vertically in its architectural characteristics. In the Everglades the result of interactions among controlling variables was that flow velocity was dominantly controlled by water surface slope variations responding to flow pulses more than spatial variation in vegetation characteristics or fluctuating water depth. Our findings indicate that floodplain managers could, in addition to managing water depth, manipulate the frequency and duration of inflow pulses to manage water surface slope, which would add further control over flow velocities, water residence times, sediment settling, biogeochemical transformations, and other processes that are important to floodplain function.

Extreme Pipetting: An Issue of Mountainous Proportions Understanding Barometric Pressure's Effect on Data Integrity (part 1)

Extreme Pipetting: An Issue of Mountainous Proportions Understanding Barometric Pressure's Effect on Data Integrity (part 1)

Sea-Level Slopes and Volume Fluxes Produced by Atmospheric Forcing in Estuaries: Chesapeake Bay Case Study

Time series at eight locations in Chesapeake Bay and the adjacent inner shelf were used to determine the relative influence of the wind and barometric pressure effects on subtidal sea-level variability and slopes in the estuary. Special emphasis was placed on the lower Chesapeake Bay, where inverse barometric effects accounted for up to 32% of the subtidal sea-level variations, and wind forcing accounted for more than 67% of the variance. The wind frequency from any given direction varied from one station to another due to the nonsynoptic characteristics of atmospheric pressure in Chesapeake Bay. In the northern bay, northwesterly winds were most frequent in winter, and southerly winds were most frequent in summer. In the southern bay, northeasterly winds were most frequent in fall and winter, and southwesterly winds dominated in the summer. These winds produced sea-level responses as follows: northeasterly winds caused water to pile up in the southwestern corner of the bay, whereas southwesterly winds produced water-level depressions in the same area. This study is one of the few to document the influence of atmospheric pressure gradients on estuarine sea-level slopes. It was found that atmospheric pressure gradients produced sea-level slopes of the same order of magnitude (10−7) as those induced by westerly–easterly winds. In contrast to previous studies, the volume fluxes calculated here, with geostrophy, geostrophy plus wind stress, and the continuity constraint, showed drainage of the bay with northerly and northwesterly winds and filling of the bay with southeasterly winds.

Estimating hydraulic properties of coastal aquifers using wave setup

Summary Wave setup is the elevated mean water-table at the coast associated with the momentum transfer of wave breaking, which occurs generally over several days. Groundwater responses to wave setup were observed as far as 5 km inland in central Maui, Hawaii. The analysis showed that at times of energetic swell events wave-driven water-table overheights dominate low-frequency groundwater fluctuations associated with barometric pressure effects. Matching peak frequencies at 1.7 × 10−6 Hz and 3.7 × 10−6 Hz were identified in setup and observed head using spectral decomposition. Similar to tides, the setup propagation through the aquifer shows exponentially decreasing amplitudes and linearly increasing time lags. Due to the longer periods of setup oscillations, the signal propagates deeper into the aquifer (∼10 km in central Maui) than diurnal tides (5 km) and can therefore provide information on greater length scales. Hydraulic diffusivity was estimated based on the setup propagation. An effective diffusivity of 2.3 × 107 m2/d is consistent with aquifer parameters based on aquifer tests and tides. A one-dimensional numerical model supports the results of the analytical solution and strengthens the suitability to estimate hydraulic parameters from setup propagation. The methodology is expected to be beneficial to high-permeability coastal environments, such as on volcanic islands and atolls.

Removal of Barometric Pressure Effects and Earth Tides from Observed Water Levels

The effects of barometric pressure and earth tide changes are often observed in ground water level measurements. These disturbances can make aquifer test interpretation difficult by masking the small changes induced by aquifer testing at late times and great distances. A computer utility is now available that automatically removes the effects of barometric pressure and earth tides from water level observations using regression deconvolution. This procedure has been shown to remove more noise then traditional constant barometric efficiency techniques in both confined and unconfined aquifers. Instead of a single, instantaneous barometric efficiency, the procedure more correctly accounts for the lagged responses caused by barometric pressure and earth tide changes. Simultaneous measurements of water levels (or total heads) and nearby barometric pressures are required. As an additional option, the effects of earth tides can also be removed using theoretical earth tides. The program is demonstrated for two data sets collected at the Waste Isolation Pilot Plant, Carlsbad, New Mexico. The program is available free by request at http://www.hydrology.uga.edu/tools.html.

Theoretical Computation of the Barometric Pressure Effects on Deformation, Gravity and Tilt

Based on the loading theory of an elastic earth, and the components of dry air and its vertical gradients of temperature under hydrostatic equilibrium, we have theoretically modeled the effects of barometric pressure on the observations of deformation, gravity and tilt. The influences of many cases, such as the adopted earth models, station height, topography around station, surface temperature and water vapor in atmosphere, on the final results are taken into account and discussed in detail. The numerical results show that the elastic effects mainly come from the atmosphere in the area far away from station. The direct effects on gravity come from the contribution of the air in area near station, while those on tilt from the contribution of the air in area far away from station. The influences of all these cases on the atmospheric gravity and tilt Green's functions mainly occur in the range of the angular distance less than 0.1 and 1 degrees, respectively, but their comprehensive influence is extremely complicated.

Micrometeorological measurements of N2O and CH4 emissions from a municipal solid waste landfill

Micrometeorological measurements of methane (CH4) and nitrous oxide (N2O) emissions were made at the decommissioned Park Road Landfill in Grimsby, Ontario, Canada between June and August 2002. The influence of precipitation, air temperature, wind speed and barometric pressure on the temporal variability of landfill biogas emissions was assessed. Gas flux measurements were obtained using a micrometeorological mass balance measurement technique [integrated horizontal flux (IHF)] in conjunction with two tunable diode laser trace gas analyser (TDLTGA) systems. This method allows for continuous, non-intrusive measurements of gas flux at high temporal resolution. Mean fluxes of N2O were negligible over the duration of the study (-0.23 to 0.02 microg m(-2) s(-1)). In contrast, mean emissions of CH4 were much greater (80.4 to 450.8 microg m(-2) s(-1)) and varied both spatially and temporally. Spatial variations in CH4 fluxes were observed between grass kill areas (biogas 'hot spots') and the densely grass-covered areas of the landfill. Temporal variations in CH4 fluxes were also observed, due at least in part to barometric pressure, wind speed and precipitation effects.

Effect of barometric pressure on sea level variations in the Pacific region

Barometric pressure and sea level data sets from the South Pacific Sea Level and Climate Monitoring Project funded by AusAID were analysed for twelve Tropical Pacific island countries. During mid-1997 and 1998 pressure anomalies over the Pacific region were strongly positive and sea level dropped significantly. As a consequence, sea level trends in the Pacific region suddenly changed from positive to negative. It was believed that the delayed effect of the 1997 strong El Ni�o episode was directly linked to these positive pressure anomalies. The same observations were made in 2002 and 2003 during another El Ni�o episode which was however not as strong as the previous one. The La Ni�a episode which followed the 1997-98 El Ni�o in 1999 had opposite effects. The pressure anomalies were negative and the sea level anomalies were positive. While the thermal effect due to global warming is still the cause of sea level rise in the Pacific region, it is clearly evident that the barometric pressure effect on sea level is more abrupt and it can overshadow the other effects at least temporarily.

Results from 44 months of observations with a superconducting gravimeter at Moxa/Germany

Abstract Results for more than 42 months of observations with the superconducting gravimeter CD-034 at the Geodynamic Observatory Moxa are discussed. Moxa observatory is one of the newer stations within the ‘Global Geodynamics Project’ (GGP). A special feature of the gravimeter at Moxa is its dual sensor system; differences in the results obtained from the two sensor recordings are generally well within the standard deviations of the tidal analysis. One significant difference concerns the slightly different drift rates of 31 and 49.5 nm/s2 per year for upper and lower sensor; both sensor drifts can be fitted by a linear function. We find that the noise levels are close to the ‘New Low Noise Model’ for the seismic-modes and are also low in the tidal bands. Due to this low noise, Moxa is a station well suited to search for small geodynamic signals. The long-period variation in the gravity residuals correlates well with the polar motion. The difference signal between the two sensor recordings has a peak-to-peak amplitude of about 6 nm/s2 and shows systematic variations. Its spectrum is characterised by instrumental noise between 0.2 and 0.4 cph. The noise level of the difference and of the sum of the two residual datasets are clearly lower, respectively, higher than the noise contents of the gravity residuals themselves. This is a strong indication for the existence of broadband signals common to the two residual datasets, leading to the conjecture that the reduction of environmental effects is still not sufficient. Our results once more emphasize the necessity to correct the data for barometric pressure effects when analyzing the data for seismic modes. The reduction visibly increases the signal-to-noise ratio in the low frequencies of the mode band and helps to avoid misinterpreations of peaks. Besides the well known barometric pressure influence we can establish hydrological effects in the data which are probably caused by soil moisture and groundwater table variations as well as by batch-wise water movement within the weathering layer. As the major part of the observatory surroundings is above gravimeter level, an anticorrelation between hydrological and gravity changes is observed. In addition, it can be shown that global hydrological effects reach an order of magnitude that makes it necessary to consider these effects when analyzing long-period signals like polar motion. Vice versa these effects are large enough to be detectable in the gravity data. A first joint analysis of five datasets from the GGP network shows no indications for signals related to the Slichter triplet or core modes.

Well Design to Reduce Barometric Pressure Effects on Water Level Data in Unconfined Aquifers

Barometric pressure fluctuations may influence measured water levels in wells where thick vadose zones or low permeability materials overlie unconfined aquifers. Here, we present a well completion method designed to reduce the effects of barometric pressure fluctuations on measured water levels. This well configuration, called the isobaric well, seals the interior of the well from atmospheric pressure, and vents the reference side of the water level pressure transducer to the gas phase pressure above the water table. We tested the isobaric design on a well completed about 180 m below land surface in the Eastern Snake River Plain aquifer at the Idaho National Engineering and Environmental Laboratory. Water level data collected during 14 mo show more than an order of magnitude decrease in diurnal fluctuations when the well was operated in the isobaric mode. Decreasing the noise level allowed clear definition of water level trends that would otherwise have been at least partially obscured by barometric fluctuations. This well configuration allows direct monitoring of water level changes, without the need to rely on postprocessing to mitigate barometric influences.

Well Design to Reduce Barometric Pressure Effects on Water Level Data in Unconfined Aquifers

Barometric pressure fluctuations may influence measured water levels in wells where thick vadose zones or low permeability materials overlie unconfined aquifers. Here, we present a well completion method designed to reduce the effects of barometric pressure fluctuations on measured water levels. This well configuration, called the isobaric well, seals the interior of the well from atmospheric pressure, and vents the reference side of the water level pressure transducer to the gas phase pressure above the water table. We tested the isobaric design on a well completed about 180 m below land surface in the Eastern Snake River Plain aquifer at the Idaho National Engineering and Environmental Laboratory. Water level data collected during 14 mo show more than an order of magnitude decrease in diurnal fluctuations when the well was operated in the isobaric mode. Decreasing the noise level allowed clear definition of water level trends that would otherwise have been at least partially obscured by barometric fluctuations. This well configuration allows direct monitoring of water level changes, without the need to rely on postprocessing to mitigate barometric influences.

Tide gauge records of uplift along the northern Pacific‐North American plate boundary, 1937 to 2001

Vertical crustal motions at 15 sites along the northern Pacific‐North America plate boundary are determined using relative sea level changes from tide gauge records. Our analysis is based on monthly mean sea levels, from which barometric pressure and seasonal effects are removed. The records are corrected for common‐mode oceanographic variations. These records are statistically examined for non‐linear behavior related to glacial isostatic, tectonic and postseismic effects. To estimate land uplift rates, the local effect of global sea level rise is removed from the relative sea level rates. Slow rates of vertical motion are observed along the southern strike‐slip plate boundary. The extremely rapid uplift of the northern strike‐slip boundary can be attributed entirely to viscoelastic postglacial rebound associated with tidewater‐glacier retreat in Glacier Bay and regional post‐Little Ice Age deglaciation. Isostatic modeling indicates a mantle viscosity of ∼2 × 1019–5 × 1019 Pa s, similar to that found elsewhere along the Pacific‐North America plate margin. At Yakutat, near the transition of plate motion from strike‐slip to subduction, complex non‐linear behavior is evident, with a significant change in uplift rate following the 1979 St. Elias earthquake. Non‐linear uplift rates are predominant within the 1964 Great Alaskan earthquake near‐field. Rapid uplift at Kodiak during a 3.5 year period starting mid‐1964 totaled 47 ± 8 cm. Anchorage, Seward and Seldovia exhibited oscillatory uplift in the period immediately following the earthquake until mid‐1972. Since mid‐1972, uplift rates have increased steadily at Anchorage, Seward, Cordova, and Valdez. During this period Nikiski and Kodiak show decreasing uplift rates.

The effect of ambient temperature and barometric pressure on ambulatory blood pressure variability

Background The effect of ambient temperature on cardiovascular disease has previously been studied. Less known are the effects of climate on blood pressure (BP) regulation, specifically, the role of temperature on BP variability. Methods: We investigated the effect of temperature and barometric pressure on ambulatory BP variability in 333 men and women with above-optimal BP or stage 1 hypertension participating in the Dietary Approaches to Stop Hypertension (DASH) multicenter feeding trial. Each subject consumed the same diet for 3 weeks. Daytime, nighttime, and 24-h BP were recorded by ambulatory BP monitoring (ABPM). Climatologic data were obtained from local meteorologic centers. Results After adjustment for body mass index (BMI), age, sex, baseline clinic systolic BP, and clinical center, systolic BP variability was inversely associated with 24-h temperature ( P = .005) and daytime temperature ( P = .006). There was no observed association between BP variability and barometric pressure. There was a significant trend of increasing nighttime systolic BP and diastolic BP with increasing temperature, but these results did not persist after adjustment for confounding variables. Conclusions During periods of cold weather, an increase in BP variability may complicate the diagnosis and management of hypertension and may contribute to the high cardiovascular mortality observed in the winter.

The effect of temperature and barometric pressure on ambulatory blood pressure variability

The effect of temperature and barometric pressure on ambulatory blood pressure variability

The Distributed Lag between Air Pollution and Daily Deaths

Many studies have reported associations between air pollution and daily deaths. Those studies have not consistently specified the lag between exposure and response, although most have found associations that persisted for more than 1 day. A systematic approach to specifying the lag association would allow better comparison across sites and give insight into the nature of the relation. To examine this question, I fit unconstrained and constrained distributed lag relations to the association between daily deaths of persons 65 years of age and older with PM10 in 10 U.S. cities (New Haven, Birmingham, Pittsburgh, Canton, Detroit, Chicago, Minneapolis, Colorado Springs, Spokane, and Seattle) that had daily monitoring for PM10. After control for temperature, humidity, barometric pressure, day of the week, and seasonal patterns, I found evidence in each city that the effect of a single day's exposure to PM10 was manifested across several days. Averaging over the 10 cities, the overall effect of an increase in exposure of 10 microg/m3 on a single day was a 1.4% increase in deaths (95% confidence intervals (CI) = 1.15-1.68) using a quadratic distributed lag model, and a 1.3% increase (95% CI = 1.04-1.56) using an unconstrained distributed lag model. In contrast, constraining the model to assume the effect all occurs in one day resulted in an estimate of only 0.65% (95% CI = 0.49-0.81), indicating that this constraint leads to a substantial underestimate of effect. Combining the estimated effect at each day's lag across the 10 cities showed that the effect was spread over several days and did not reach zero until 5 days after the exposure. Given the distribution of sensitivities likely in the general population, this result is biologically plausible. I also found a protective effect of barometric pressure in all 10 locations.

Comparison of different barometric pressure reductions for gravity data and resulting consequences

Different methods of barometric pressure reductions are applied on data recorded with the superconducting gravimeter at Potsdam, Germany. The results are compared regarding their success in removing barometric pressure effects in different frequency ranges. Among the corrections, pure regression methods are used as well as a combination of a physical correction using atmospheric Green's functions [Merriam, J.B., 1992. Atmospheric pressure and gravity. Geophys. J. Int. 109, 488–500; Merriam, J.B., 1995. The atmospheric pressure correction in gravity at Cantley Quebec. In: Hsu, H.T. (Ed.), Proceedings of the 12th International Symposium on Earth Tides. Science Press, Beijing, pp. 161–168; Sun, H.-P., 1995. Static deformation and gravity changes at the earth's surface due to the atmospheric pressure. PhD Thesis, Cath. Univ. Louvain, Belgium] and a local reduction coefficient. This combination is required due to the lack of a sufficient number of local barometric pressure data sets. After applying the physical correction on the gravity data, the local coefficient is determined in two ways: as a fit between station pressure and the partly pressure corrected gravity and as a theoretical value calculated with atmospheric Green's functions and station pressure. The efficiency of the corrections is compared by the results of tidal and spectral analyses as well as coherences between corrected, detided gravity and barometric pressure. In comparison to the standard correction with one regression coefficient, we get similar or slightly improved corrections (depending on the frequency) when applying a frequency-dependent admittance or a correction including atmospheric Green's functions. In general, we find no or only small differences in the corrections that emerge for short periods (periods≤2 days) and bigger changes in the long-periodic range (periods>2 days). We attribute the lacking improvement in the short periods to the partly too low sampling rate of the pressure data and the necessity to have more pressure data sets from the local area around the gravimeter available. Our studies of lateral pressure variations occurring in the local zone indicate a significant lateral pressure variability. A model calculation regarding the influence of these deviations on the pressure reduction yields the necessity of a better consideration of them in the correction. We conclude that one step towards an improved reduction of barometric pressure effects is to redo corrections that include atmospheric Green's functions in combination with regional hourly pressure data as well as data from a local pressure network surrounding the gravimeter location.

Experimental monitoring of carbon dioxide by low power IR-sensors: soil degassing in the Furnas Volcanic Centre, Azores

In October 1993 two experimental carbon dioxide sensors were installed at the Furnas Volcanic Centre, São Miguel. The monitoring sites are tilt meter stations in Furnas Village and at Castelo Branco on the SW-caldera rim. The selection of these observation sites is meant to record changes in carbon dioxide outgassing close to an active fumarole ground (Furnas Village, 3 m deep well) and at an outer caldera wall (Castelo Branco, 6 m deep well) where geothermal processes are definitely absent. Recording of carbon dioxide was made for one year by hourly readings, from October 1993 to October 1994. The experiment revealed carbon dioxide pulses characterised by short rise times (hours) and fading on the time scale of days. Interpretation of the data in relation to meteorological conditions is preliminary and suggestive. An overall covariation of carbon dioxide outgassing and changes in atmospheric pressure and/or precipitation is observed at the Calderas fumarole grounds of the Furnas Village. A favoured degassing mechanism is based on increased out-diffusion of carbon dioxide from the soil layer at the onset of low pressure intervals due to increased boiling and carbon dioxide release from the shallow local hydrothermal aquifers. Increased soil degassing after heavy rain is attributed to closure of the porous surface layer resulting in an increased partial pressure of carbon dioxide at the base of the instrument well. At the Castelo Branco station, which is located on a narrow ridge some 20 m above the surroundings, the opposite effect of barometric pressure is observed on the very low carbon dioxide flux. This still unexplained covariation may be related to chemical conditions within the soil during high pressure (dry soil) and low pressure (wet soil) periods. After every impulsive increase in carbon dioxide flux, the normal baseline is slowly reached. A periodic effect on soil degassing, to a first approximation of tidal origin, cannot be excluded at Castelo Branco. It is concluded that the experimental sensors are adequate for detailed long-standing evaluation of monitoring sites which needed prior to permanent monitoring of soil degassing.

Monitoring the Hydraulic Performance of a Containment System with Significant Barometric Pressure Effects

Under certain circumstances, wells in unconfined aquifers can display significant water level fluctuations in response to changes in barometric pressure. This is illustrated by Hare and Morse (1997) at a site where a portion of the unconfined aquifer is isolated by a soil-bentonite cutoff wall and clay cap. A relief well located within the containment system displays water level fluctuations that mirror barometric pressure changes. Water levels fluctuated 0.37 m in response to barometric pressure changes of 2.87 centimeters mercury (cm-Hg), representing a barometric efficiency of 93.6%. As described in this paper, the short-term variability in water level elevations inside the containment system had to be considered to develop a reliable post-enhancement performance monitoring program. The approach that was ultimately selected involves correcting the water level elevations obtained in the relief well within the containment system for the effects of barometric pressure changes prior to comparison with the water level elevations in an observation well in the aquifer outside the system. The reliability of the post-enhancement performance monitoring program is improved further by simply requiring that any decision to enhance the containment system be based on the water level measurements obtained during two consecutive months. Using this approach, the probability that the containment system's performance will erroneously be deemed unacceptable is low. The post-enhancement performance monitoring program also requires no extra field work and does not involve any specialized equipment, which helps to keep operation and maintenance costs to a minimum.