Atmospheric Pressure Variations Research Articles

A Numerical Study on Long-Wave Generation and Propagation due to Atmospheric-Pressure Variation

A Numerical Study on Long-Wave Generation and Propagation due to Atmospheric-Pressure Variation

Does environmental noise really affect reef fish behavior or are they talking while we cannot listen to them?

Although it has been hypothesized that reef fish reduces sound production during extreme environmental events, it is possible that fish sounds are still present but only masked by elevated environmental noise. Although available acoustic technology makes it difficult to address this question, we can still generate hypotheses about the impact of environmental noise on fish sound production. Is there a behavioral response to environmental noise, or are fish sounds present at the same levels but masked and therefore undetectable without adequate filters? We recorded sciaenid (Pisces: Sciaenidae) sound production around Isla Tortuga, Costa Rica, during the “Nortes,” a period of strong winds caused by cold fronts and extreme variation of atmospheric pressure. Sciaenid sounds apparently stopped with almost no emissions during strong winds (56 miles/h) and transitioned to the normal emission rate on the next day when winds receded to 2 miles/h. We hypothesize that fish sounds were present at all times, but masked by wind-produced noise instead of a biological modulation as described by Mann and Grothues (2009) in similar conditions. I present circumstantial evidence in support of this hypothesis and discuss possible methods to test it directly.

Spectral and geographical variability in the oceanic response to atmospheric pressure fluctuations, as inferred from “dynamic barometer” Green's functions

A decade ago, a novel theoretical approach was developed (Dickman, 1998) for determining the dynamic response of the oceans to atmospheric pressure variations, a response nicknamed the “dynamic barometer” (DB), and the effects of that response on Earth's rotation. This approach employed a generalized, spherical harmonic ocean tide model to compute oceanic Green's functions, the oceans' fluid dynamic response to unit‐amplitude pressure forcing on various spatial and temporal scales, and then construct rotational Green's functions, representing the rotational effects of that response. When combined with the observed atmospheric pressure field, the rotational Green's functions would yield the effects of the DB on Earth's rotation. The Green's functions reflect in some way the geographical and spectral sensitivity of the oceans to atmospheric pressure forcing. We have formulated a measure of that sensitivity using a simple combination of rotational Green's functions. We find that the DB response of the oceans to atmospheric pressure forcing depends significantly on geographic location and on frequency. Compared to the inverted barometer (IB) (the traditional static model), the DB effects differ slightly at long periods but become very different at shorter periods. Among all the responses, the prograde polar motion effects are the most dynamic, with large portions of the North Atlantic and some of the North Pacific no larger than one third of IB, but most of the Southern Hemisphere oceans at least 50% greater than IB.

Topographically induced height errors in predicted atmospheric loading effects

Atmospheric pressure variations are known to induce vertical displacements of the Earth's surface with magnitudes large enough to be detected by geodetic observations. Estimates of these loading effects are derived using global reanalysis fields of surface pressure as input. The input surface pressure has a minimum spatial sampling, which does not capture true surface pressure variations due to high topographic variability in some regions. In this paper, we investigate the effect that unmodeled topographic variability has on surface pressure estimates and subsequent estimates of vertical surface displacements. We find that the estimated height changes from the topographic surface pressure can be significant (2–4 mm) for sites in regions of high topographic variability. When we compare the estimated height changes to Global Positioning System residuals from the 2005 International Terrestrial Reference Frame Realization, we find that the heights derived from the topographic surface pressure, versus those from the normal surface pressure, perform better at reducing the scatter on the height coordinate time series.

Galactic cosmic ray variation influence on baric system dynamics at middle latitudes

Variations of atmospheric pressure in the North Atlantic region during Forbush decreases of galactic cosmic rays were investigated. A noticeable pressure growth with the maximum on the 3rd and 4th days after the Forbush decrease onsets was revealed over Scandinavia and the northern region of the European part of Russia. It was shown that the observed pressure growth was caused by the formation of blocking anticyclones in the region of the climatic Arctic front, as well as by the sharp slowing of the movement of North Atlantic cyclones. It was suggested that the particles that precipitate in the regions of the climatic Arctic and Polar fronts, with the minimum energies E∼20–80 MeV and ∼2–3 GeV, respectively, may influence the processes of cyclone and anticyclone formation and development at extratropical latitudes.

Rotational evaluation of a long-period spherical harmonic ocean tide model

By exchanging angular momentum with the solid earth, tidal variations in ocean currents and sea level cause the rotation of the solid earth to change. Observations of earth rotation variations can therefore be used to evaluate ocean tide models. The rotational predictions of a spherical harmonic ocean tide model that is not constrained by any type of data are compared here to the predictions of numerical ocean tide models and to earth rotation observations from which atmospheric and non-tidal oceanic effects have been removed. The spherical harmonic ocean tide model is shown to account for the observed variations at the fortnightly tidal period in polar motion excitation but not in length-of-day. Overall, its long-period polar motion excitation predictions fit the observed tidal signals better than do the predictions of the numerical ocean tide models studied here. It may be possible to improve its agreement with length-of-day observations by tuning certain model parameters, as was done to obtain the close agreement reported here between the modeled and observed polar motion excitation; alternatively, the discrepancy in length-of-day may point to the need to revise current models of mantle anelasticity and/or models of the oceanic response to atmospheric pressure variations.

Spatial and Temporal Dependence of Temperature Variations Induced by Atmospheric Pressure Variations in Shallow Underground Cavities

Pressure-induced temperature (PIT) variations are systematically observed in the atmosphere of underground cavities. Such PIT variations are due to the compressibility of the air, damped by heat exchange with the rock surface. It is important to characterize such processes for numerous applications, such as the preservation of painted caves or the assessment of the long-term stability of underground laboratories and underground waste repositories. In this paper we thoroughly study the spatiotemporal dependence of the PIT response versus frequency using vertical and horizontal profiles of temperature installed in an abandoned underground quarry located in Vincennes, near Paris. The PIT response varies from about 20 × 10−3°C hPa−1 at a frequency of 2 × 10−4 Hz to 2–3 × 10−3°C hPa−1 at a frequency of one cycle per day. An analytical expression based on a simple heat exchange model accounts for the observed features of the PIT response and allows for correcting the measured time series, having standard deviations of about 10−2°C, to residual variations with a standard deviation of about 2 × 10−3°C. However, a frequency-dependent attenuation of the response, corresponding to a reduction in amplitude with a factor varying from 2 to 3, is observed near the walls. This effect is not included in the simple analytical expression, but it can be accounted for by a one-dimensional differential equation, solved numerically, where temperature variations in the atmosphere are damped by an effective radiative coupling with the rock surface, complemented by a diffusive coupling near the walls. The TIP response is observed to remain stable over several years, but a large transient enhancement of about a factor of two is observed near the roof at one location from July to October 2005. In a cavity located below the Paris Observatory, an additional contribution is identified in the PIT response function versus frequency for frequencies smaller than 2 × 10−5 Hz. This contribution can be described using a modified analytical expression that includes the effect of heat diffusion into the surrounding rock. Using this expression, in this case also, the temperature time series can then be corrected, giving a residual standard deviation smaller than 1.6 × 10−3°C. Transient temporal variations of the PIT response are observed in all sites, with possible nonlinear components in the PIT. Such effects are not properly understood at this stage, and limit the reduction of time series to standard deviations of the order of 2 × 10−3°C, and consequently limit the search for new transient or seasonal temperature signals, for example due to the presence of tiny heat sources in the cavity or to geodynamical effects.

Investigation of diurnal variations of cosmic ray fluxes measured with using ASEC and NMDB monitors

A study of daily variations of secondary Cosmic Rays (CR) is performed using data on charged and neutral CR fluxes. Particle detectors of Aragats Space-Environmental Center (ASEC), Space Environmental Viewing and Analysis Network (SEVAN) and neutron monitors of the Neutron Monitor Database (NMDB) are used. ASEC detectors continuously register various species of secondary CR with different threshold energies and incident angles. NMDB joins data of 12 Eurasian neutron monitors. Data at the beginning of the 24th solar activity cycle are used to avoid biases due to solar transient events and to establish a benchmark for the monitoring of solar activity in the new started solar cycle. After eliminating changes associated with atmospheric pressure variations, solar diurnal variations are clearly seen in muon and neutron fluxes. Neutrons daily variations magnitudes, corresponding to the lowest energy primary protons, are comparable with the magnitudes of variations of charged secondary CR. Diurnal variations of neutron flux are higher for the high latitudes comparing with middle latitudes. For low energy muons, the variations are bigger comparing higher energy muons.

Spatiotemporal variation of radon and carbon dioxide concentrations in an underground quarry: coupled processes of natural ventilation, barometric pumping and internal mixing

Radon-222 and carbon dioxide concentrations have been measured during several years at several points in the atmosphere of an underground limestone quarry located at a depth of 18 m in Vincennes, near Paris, France. Both concentrations showed a seasonal cycle. Radon concentration varied from 1200 to 2000 Bq m −3 in summer to about 800–1400 Bq m −3 in winter, indicating winter ventilation rates varying from 0.6 to 2.5 × 10 −6 s −1. Carbon dioxide concentration varied from 0.9 to 1.0% in summer, to about 0.1–0.3% in winter. Radon concentration can be corrected for natural ventilation using temperature measurements. The obtained model also accounts for the measured seasonal variation of carbon dioxide. After correction, radon concentrations still exhibit significant temporal variation, mostly associated with the variation of atmospheric pressure, with coupling coefficients varying from −7 to −26 Bq m −3 hPa −1. This variation can be accounted for using a barometric pumping model, coupled with natural ventilation in winter, and including internal mixing as well. After correction, radon concentrations exhibit residual temporal variation, poorly correlated between different points, with standard deviations varying from 3 to 6%. This study shows that temporal variation of radon concentrations in underground cavities can be understood to a satisfactory level of detail using non-linear and time-dependent modelling. It is important to understand the temporal variation of radon concentrations and the limitations in their modelling to monitor the properties of natural or artificial underground settings, and to be able to assess the existence of new processes, for example associated with the preparatory phases of volcanic eruptions or earthquakes.

Influencia de los cambios de presión atmosférica y otras variables meteorológicas en la incidencia de la hemorragia subaracnoidea

Spontaneous subarachnoid hemorrhage is a pathology usually related to risk factors, such as arterial hypertension and/or nicotine poisoning. Nevertheless, other variables exist, like meteorological changes, that although the experience aims as possible responsible for an increase of the incidence, are still not established like such.It is to investigate the influence of the meteorological changes, either seasonal variations or changes of atmospheric pressure, in the incidence of the subarachnoid hemorrhage.All the cases of spontaneous subarachnoid hemorrhage are considered from the 1st of January from 1997 to the 31st of March of 2008, making a medical registry of demographic aspects (age, sex) and antecedents (arterial hypertension, diabetes mellitus, cerebral ischemia, nicotine poisoning), as well as numbers of atmospheric pressure (in hectopascales, hPa), daily temperature and relative humidity, throughout this period, with a calculation of the maximum, average and minimum values, as well as pressure differentials between consecutive days.The analysis of the 173 gathered cases showed a predominance of the subarachnoid hemorrhage in female, specially the aneurismal ones, being arterial hypertension, the main factor of related risk. Significant differences between the days with and without hemorrhage were not demonstrated, in relation to the variation of atmospheric pressure (p 0.463), pressure temperature (p 0.381) and relative humidity (p 0.595) throughout the day.In our element, the variations of atmospheric pressure are not related to an increase of incidence of the subarachnoid hemorrhage. Instead of this, cases of subarachnoid hemorrhage take place with changes of hardly 1.7 (1-3) hPa in the day, without observing a clear seasonal tendency.

10.1007/s11486-008-1004-3

Retrospective data of monitoring under conditions of low seismic activity are used to identify free oscillations of the Earth, including the fundamental mode, the oscillation with a central period of 54 min (0 S 2 multiplet), split into five lines with azimuthal numbers m = −2, −1, 0, 1, 2. It is shown that some lines of this oscillation are also recorded in atmospheric pressure variation spectra and group in ensembles of observations around frequencies predicted by the 0 S 2 splitting theory. This phenomenon is discovered in data recorded both synchronously and in different time intervals. A causal relationship involved in the oscillation under study is determined on the basis of the examination of the direction of the acoustic energy flux. The energy flux in the region of the 0 S 2 multiplet is shown to be directed from the Earth toward the atmosphere. This suggests that deep processes in the Earth are capable of exciting its upper shells.

Influence of atmospheric pressure variation in patients with rheumatoid arthritis

Influence of atmospheric pressure variation in patients with rheumatoid arthritis

Spectral analysis of the clinometric data at the Phlegraean Fields from 1992 to 1998

Ground deformation is one of the most important precursors for volcanic eruptions. In this respect, the surveillance of volcanoes has greatly benifited from the continuous recording of clinometric data, which represents an economical and reliable way to identify significant ground deformations. In this paper we analyize the clinometric data recorded at the Phlegraean Fields, Italy, in the period 1992-1998 through a classical time series analysis. We show that these techniques can be advantageously used to discriminate between the signals relative to the internal and external processes. In particular, we find that high-frequency fluctuations are mainly due to thermal and atmospheric pressure variations, while at lower frequencies we highlight a constant subsidence, without any evidence of volcanic reactivation.

Crustal loading in vertical GPS time series in Fennoscandia

We compare time series of vertical position from GPS with modelled vertical deformation caused by variation in continental water storage, variation in the level of the Baltic Sea, and variation in atmospheric pressure. Monthly time series are used. The effect of continental water storage was calculated from three different global models. The effect of non-tidal variation in Baltic Sea level was calculated using tide gauge observations along the coasts. Atmospheric loading was computed from a numerical weather model. The loading time series are then compared with three different GPS time series at seven stations in Fennoscandia. A more detailed analysis is computed at three coastal stations. When the monthly GPS time series are corrected using the load models, their root-mean-square scatter shows an improvement between 40 and 0%, depending on the site and on the GPS solution. The modelled load effect shows a markedly seasonal pattern of 15 mm peak-to-peak, of which the uncorrected GPS time series reproduce between 60 and 0%.

Patterns and processes in the California Current System

The California Current System (CCS) is forced by the distribution of atmospheric pressure and associated winds in relation to the west coast of North America. In this paper, we begin with a simplified case of winds and a linear coast, then consider variability characteristic of the CCS, and conclude by considering future change. The CCS extends from the North Pacific Current (∼50°N) to off Baja California, Mexico (∼15–25°N) with a major discontinuity at Point Conception (34.5°N). Variation in atmospheric pressure affects winds and thus upwelling. Coastal, wind-driven upwelling results in nutrification and biological production and a southward coastal jet. Offshore, curl-driven upwelling results in a spatially large, productive habitat. The California Current flows equatorward and derives from the North Pacific Current and the coastal jet. Dominant modes of spatial and temporal variability in physical processes and biological responses are discussed. High surface production results in deep and bottom waters depleted in oxygen and enriched in carbon dioxide. Fishing has depleted demersal stocks more than pelagic stocks, and marine mammals, including whales, are recovering. Krill, squid, and micronekton are poorly known and merit study. Future climate change will differ from past change and thus prediction of the CCS requires an understanding of its dynamics. Of particular concern are changes in winds, stratification, and ocean chemistry.

Influence of lower stratosphere/upper troposphere transport events on surface ozone at the Everest-Pyramid GAW Station (Nepal): first year of analysis

In this work, we present the first systematic identification of episodes of air mass transport from the lower stratosphere/upper troposphere (LS/UT) in the middle troposphere of the southern Himalayas. For this purpose, we developed an algorithm to detect LS/UT transport events on a daily basis at the Everest-Pyramid GAW station (EV-PYR, 5079 m a.s.l., Nepal). In particular, in situ surface ozone and atmospheric pressure variations as well as total ozone values from OMI satellite measurements have been analysed. Further insight is gained from three-dimensional backward trajectories and potential vorticity calculated with the LAGRANTO model. According to the algorithm outputs, 9.0% of the considered data set (365 days from March 2006 to February 2007) was influenced by this class of phenomena with a maximum of frequency during dry and pre-monsoon seasons. During 25 days of LS/UT transport events for which any influence of anthropogenic pollution was excluded, the daily ozone mixing ratio increased by 9.3% compared to the seasonal values. This indicates that under favourable conditions, downward air mass transport from the LS/UT can play a considerable role in determining the concentrations of surface ozone in the southern Himalayas.

Atmospheric pressure ion sources

This review of atmospheric pressure ion sources discusses major developments that have occurred since 1991. Advances in the instrumentation and understanding of the key physical principles are the primary focus. Developments with electrospray and atmospheric pressure chemical ionization and variations encompassing adaptations for surface analysis, ambient air analysis, high throughput, and modification of the ionization mechanism are covered. An important and limiting consequence of atmospheric pressure chemical ionization, chemical noise, is discussed as is techniques being employed to ameliorate the problem. Ion transfer and transport from atmospheric pressure into deep vacuum is an area undergoing constant improvement and refinement so is given considerable consideration in this review.

Frequency stability measurement of a transfer-cavity-stabilized diode laser by using an optical frequency comb

We report results of frequency stability measurements of an extended cavity diode laser (ECDL) whose frequency is stabilized by a non-evacuated scanning transfer cavity. The transfer cavity is locked to a commercial frequency stabilized helium–neon laser. Frequency stability is measured by use of an optical frequency comb. The environmental perturbations (variations of temperature, air pressure, and humidity) are also simultaneously measured. The observed frequency drift of the ECDL is well explained by environmental perturbations. An atmospheric pressure variation, which is difficult to control with a non-evacuated cavity, is mainly affected to the frequency stability. Thus we put the cavity into a simple O-ring sealed (non-evacuated) tube. With this simple O-ring sealed tube, the frequency drift is reduced by a factor of 3, and the Allan variance reaches a value of 2.4×10−10, corresponds to the frequency stability of 83 kHz, at the average time of 3000 s. Since the actual frequency drift is well estimated by simultaneous measurement of the ambient temperature, pressure, and humidity, a feed-forward compensation of frequency drifts is also feasible in order to achieve a higher frequency stability with a simple non-evacuated transfer cavity.

Evaluation and validation of mascon recovery using GRACE KBRR data with independent mass flux estimates in the Mississippi Basin

The direct recovery of surface mass anomalies using GRACE KBRR data processed in regional solutions provides mass variation estimates with 10-day temporal resolution. The approach undertaken herein uses a tailored orbit estimation strategy based solely on the KBRR data and directly estimates mass anomalies from the GRACE data. We introduce a set of temporal and spatial correlation constraints to enable high resolution mass flux estimates. The Mississippi Basin, with its well understood surface hydrological modelling available from the Global Land Data Assimilation System (GLDAS), which uses advanced land surface modeling and data assimilation techniques, and a wealth of groundwater data, provides an opportunity to quantitatively compare GRACE estimates of the mass flux in the entire hydrological column with those available from independent and reliable sources. Evaluating GRACE’s performance is dependent on the accuracy ascribed to the hydrological information, which in and of itself is a complex challenge (Rodell in Hydrogeol J, doi:10.​1007/​s10040-006-0103-7, 2007). Nevertheless, the Mississippi Basin is one of the few regions having a large hydrological signal that can support a meaningful GRACE comparison on the spatial scale resolved by GRACE. The isolation of the hydrological signal is dependent on the adequacy of the forward mass flux modeling for tides and atmospheric pressure variations. While these models have non-uniform global performance they are excellent in the Mississippi Basin. Through comparisons with the independent hydrology, we evaluate the effect on the solution of changing correlation times and distances in the constraints, altering the parameter recovery for areas external to the Mississippi Basin, and changing the relative strength of the constraints with respect to the KBRR data. The accuracy and stability of the mascon solutions are thereby assessed, especially with regard to the constraints used to stabilize the solution. We show that the mass anomalies, as represented by surface layer of water within regional cells have accuracy estimates of ±2–3 cm on par with the best hydrological estimates and consistent with our accuracy estimates for GRACE mass anomaly estimates. These solutions are shown to be very stable, especially for the recovery of semi-annual and longer period trends, where for example, the phase agreement for the dominant annual signal agrees at the 10-day level of resolution provided by GRACE. This validation confirms that mascons provide critical environmental data records for a wide range of applications including monitoring ground water mass changes.

Sea level variability and the ‘ Milghuba’ seiche oscillations in the northern coast of Malta, Central Mediterranean

The characteristics of the water level variations in the northern coastal area of Malta are studied by a set of densely sampled data collected in the period 1993–1996 (43 months) at a permanent coastal sea level installation in Mellieha Bay. These measurements constitute the first digitised sea level recordings in the Maltese Islands and were collected as part of a research programme that produced a long time series of simultaneous water level and meteorological parameters in the Central Mediterranean. Tidal oscillations reach a maximum range of only 20.6 cm on average and are predominantly semi-diurnal. Important non-tidal signals are however found to span the whole spectral range of frequencies. Seiche oscillations in the form of large amplitude sea level fluctuations, known locally as the ‘ milghuba’, carry substantial energy in the range of long wave frequencies (0.2–2 cph) and often mask completely the tidal signal. These coastal seiches are believed to be the expression of shelf scale resonances; in the numerous embayments on the northern coastline of the Maltese Islands, these seiches are greatly amplified and have associated swift alternating currents that are useful for the mixing and exchange of the water body in the embayments with the adjoining open sea areas, but can constitute a nuisance to navigation especially at harbour entrances. In the synoptic and sub-synoptic time scales, variations in atmospheric pressure associated with mesoscale meteorological phenomena produce a predominant effect on the sea level, but the response of the sea is non-isostatic and carries the signature of oceanographic conditions in the region as well as that of non-local forcing resulting from intra-basin differences. Strong seasonal non-eustatic fluctuations in the mean sea level are characterised by a high sea level in December and is typically followed by a sharp fall to a minimum in February/March. This seasonal variability is a manifestation of the adjustments in the mass balance of the whole Mediterranean basin.