scholarly journals Pipes to Earth's subsurface: the role of atmospheric conditions in controlling air transport through boreholes and shafts

2018 ◽  
Vol 9 (3) ◽  
pp. 1141-1153 ◽  
Author(s):  
Elad Levintal ◽  
Nadav G. Lensky ◽  
Amit Mushkin ◽  
Noam Weisbrod
Keyword(s):  
Large Diameter ◽  
Absolute Humidity ◽  
Field Measurements ◽  
Barometric Pressure ◽  
Atmospheric Temperature ◽  
Air Transport ◽  
Atmospheric Conditions ◽  
Air Masses ◽  
Diurnal Cycles

Abstract. Understanding air exchange dynamics between underground cavities (e.g., caves, mines, boreholes, etc.) and the atmosphere is significant for the exploration of gas transport across the Earth–atmosphere interface. Here, we investigated the role of atmospheric conditions in controlling air transport inside boreholes using in situ field measurements. Three geometries were explored: (1) a narrow and deep shaft (0.1 m wide and 27 m deep), ending in a large underground cavity; (2) the same shaft after the pipe was lowered and separated from the cavity; and (3) a deep large-diameter borehole (59 m deep and 3.4 m wide). Absolute humidity was found to be a reliable proxy for distinguishing between atmospheric and cavity air masses (mainly during the winter and spring seasons) and thus to explore air transport through the three geometries. Airflow directions in the first two narrow-diameter geometries were found to be driven by changes in barometric pressure, whereas airflow in the large-diameter geometry was correlated primarily with the diurnal cycles of ambient atmospheric temperature. CO2 concentrations of ∼2000 ppm were found in all three geometries, indicating that airflow from the Earth's subsurface into the atmosphere may also be significant in the investigation of greenhouse gas emissions.

scholarly journals Pipes to Earth's subsurface: The role of atmospheric conditions in controlling air transport through boreholes and shafts

2018 ◽  
Author(s):  
Elad Levintal ◽  
Nadav G. Lensky ◽  
Amit Mushkin ◽  
Noam Weisbrod
Keyword(s):  
Large Diameter ◽  
Absolute Humidity ◽  
Barometric Pressure ◽  
Atmospheric Temperature ◽  
Air Transport ◽  
Atmospheric Conditions ◽  
Air Masses ◽  
Diurnal Cycles

Abstract. Understanding air exchange dynamics between underground cavities (e.g., caves, mines, boreholes, etc.) and the atmosphere is significant for the exploration of gas transport across the Earth-atmosphere interface. Here, we investigated the role of atmospheric conditions in air transport inside boreholes through in-situ observations. Three geometries were explored: (1) a narrow and deep shaft (0.1 m and 27 m, respectively), ending in a large underground cavity; (2) the same shaft after the pipe was lowered and separated from the cavity; and (3) a deep large-diameter borehole (3.4 m and 59 m, respectively). Absolute humidity was found to be a reliable proxy for distinguishing between atmospheric and cavity air masses and thus to explore air transport through the three geometries. Airflow directions in the first two narrow-diameter geometries were found to be driven by changes in barometric pressure whereas airflow in the large-diameter geometry was correlated primarily to the diurnal cycles of ambient atmospheric temperature. High CO2 concentrations (~ 2000 ppm) were found in all three geometries, which can indicate that the airflow to the atmosphere is also significant to the investigation of greenhouse gas emissions.

scholarly journals Atmospheric extremes triggered the biggest calving event in more than 50 years at the Amery Ice shelf in September 2019

2020 ◽  
Author(s):  
Diana Francis ◽  
Kyle S. Mattingly ◽  
Stef Lhermitte ◽  
Marouane Temimi ◽  
Petra Heil
Keyword(s):  
High Pressure ◽  
Sea Level ◽  
Ice Sheet ◽  
Atmospheric Conditions ◽  
Ice Shelf ◽  
Air Masses ◽  
Sources Of Uncertainty ◽  
Amery Ice Shelf ◽  
Heat And Moisture

Abstract. Ice shelf instability is one of the main sources of uncertainty in Antarctica's contribution to future sea level rise. Calving events play crucial role in ice shelf weakening but remain unpredictable and their governing processes are still poorly understood. In this study, we analyze the unexpected September 2019 calving event from the Amery Ice Shelf, the largest since 1963 and which occurred almost a decade earlier than expected, to better understand the role of the atmosphere in calving. We find that atmospheric extremes provided a deterministic role in this event. The calving was triggered by the occurrence of a series of anomalously-deep and stationary explosive twin polar cyclones over the Cooperation and Davis Seas which generated strong offshore winds leading to increased sea ice removal, fracture amplification along the pre-existing rift, and ultimately calving of the massive iceberg. The observed record-anomalous atmospheric conditions were promoted by blocking ridges and Antarctic-wide anomalous poleward transport of heat and moisture. Blocking highs helped in (i) directing moist and warm air masses towards the ice shelf and in (ii) maintaining stationary the observed extreme cyclones at the front of the ice shelf for several days. Accumulation of cold air over the ice sheet, due to the blocking highs, led to the formation of an intense cold-high pressure over the ice sheet, which helped fuel sustained anomalously-deep cyclones via increased baroclinicity. Our results stress the importance of atmospheric extremes in ice shelf instability and the need to be accounted for when considering Antarctic ice shelf variability and contribution to sea level, especially given that more of these extremes are predicted under a warmer climate.

Impact of dust and sand storms on the aviation operation and assessment of conditions for their occurrence at aerodromes in European Russia

2020 ◽  
Vol 4 ◽  
pp. 78-95
Author(s):  
A.R. Ivanova ◽  
◽  
E.N. Skriptunova ◽  
N.I. Komasko ◽  
A.A. Zavialova ◽  
...  
Keyword(s):  
Seasonal Variations ◽  
Dust Storms ◽  
European Russia ◽  
Air Transport ◽  
Review Of Literature ◽  
Dust Transport ◽  
Air Masses ◽  
The Past ◽  
Sand Storm ◽  
The Impact

A review of literature on the impact of dust and sand storms on the air transport operation is presented. Observational data on dust storms at the aerodromes of European Russia for the period of 2001-2019 are analyzed. The seasonal variations in dust transport episodes at aerodromes and its relationship with visibility changes are discussed. The characteristics of dusty air masses and advection are given. It is concluded that the frequency of dust transfer episodes for the aerodromes under study has decreased over the past five years, except for Gumrak aerodrome (Volgograd). Keywords: dust storm, sand storm, aviation, visibility, seasonal variations, aerodrome оf European Russia

Saturated Hydraulic Conductivity of Clayey Tills and the Role of Fractures

1990 ◽  
Vol 21 (2) ◽  
pp. 119-132 ◽  
Author(s):  
Johnny Fredericia
Keyword(s):  
Hydraulic Conductivity ◽  
American Studies ◽  
Field Measurements ◽  
Present Knowledge ◽  
Saturated Hydraulic Conductivity ◽  
Field Observations ◽  
Laboratory Measurements ◽  
Vertical Hydraulic Conductivity ◽  
Data Field

The background for the present knowledge about hydraulic conductivity of clayey till in Denmark is summarized. The data show a difference of 1-2 orders of magnitude in the vertical hydraulic conductivity between values from laboratory measurements and field measurements. This difference is discussed and based on new data, field observations and comparison with North American studies, it is concluded to be primarily due to fractures in the till.

scholarly journals Novel role of endothelial BKCa channels in altered vasoreactivity following hypoxia

2010 ◽  
Vol 299 (5) ◽  
pp. H1439-H1450 ◽  
Author(s):  
Jennifer M. Hughes ◽  
Melissa A. Riddle ◽  
Michael L. Paffett ◽  
Laura V. Gonzalez Bosc ◽  
Benjimen R. Walker
Keyword(s):  
Ex Vivo ◽  
Barometric Pressure ◽  
Channel Blockers ◽  
Channel Activity ◽  
Resistance Arteries ◽  
Bkca Channels ◽  
Oxide Synthase ◽  
Increased Activity ◽  
Small Conductance

The systemic vasculature exhibits attenuated vasoconstriction following hypobaric chronic hypoxia (CH) that is associated with endothelium-dependent vascular smooth muscle (VSM) cell hyperpolarization. We hypothesized that increased activity of endothelial cell (EC) large-conductance, calcium-activated potassium (BKCa) channels contributes to this response. Gracilis resistance arteries from hypobaric CH (barometric pressure = 380 mmHg for 48 h) rats demonstrated reduced myogenic reactivity and hyperpolarized VSM membrane potential ( Em) compared with controls under normoxic ex vivo conditions. These differences were eliminated by endothelial disruption. In the presence of cyclooxygenase and nitric oxide synthase inhibition, combined intraluminal administration of the intermediate and small-conductance, calcium-activated K+ channel blockers TRAM-34 and apamin was without effect on myogenic responsiveness and VSM Em in both groups; however, these variables were normalized in CH arteries by intraluminal administration of the BKCa inhibitor iberiotoxin (IBTX). Basal EC Em was hyperpolarized in arteries from CH rats compared with controls and was restored by IBTX, but not by TRAM-34/apamin. K+ channel blockers were without effect on EC basal Em in controls. Similarly, IBTX blocked acetylcholine-induced dilation in arteries from CH rats, but was without effect in controls, whereas TRAM-34/apamin eliminated dilation in controls. Acetylcholine-induced EC hyperpolarization and calcium responses were inhibited by IBTX in CH arteries and by TRAM-34/apamin in controls. Patch-clamp experiments on freshly isolated ECs demonstrated greater K+ current in cells from CH rats that was normalized by IBTX. IBTX was without effect on K+ current in controls. We conclude that hypobaric CH induces increased endothelial BKCa channel activity that contributes to reduced myogenic responsiveness and EC and VSM cell hyperpolarization.

Effects of atmospheric temperature and pressure on the performance of a vehicle

2002 ◽  
Vol 216 (6) ◽  
pp. 473-477 ◽  
Author(s):  
S M C Soares ◽  
J R Sodre
Keyword(s):  
Ambient Temperature ◽  
Sea Level ◽  
Fuel Injection ◽  
Atmospheric Temperature ◽  
Intake Manifold ◽  
Atmospheric Conditions ◽  
Fixed Temperature ◽  
Vehicle Performance ◽  
The Road ◽  
On The Road

This paper describes the influence of the atmospheric conditions on the performance of a vehicle. Tests were carried out on the road, under different conditions of ambient temperature, pressure and humidity, measuring the acceleration time. The tested vehicle featured a gasoline-fuelled four-cylinder engine, with variable intake manifold length and multipoint fuel injection. The vehicle was tested at sea level and at an altitude of 827 m above sea level, with the ambient temperature ranging from 20 to 30°C. The times required for the vehicle to go from 80 to 120 km/h, from 40 to 100 km/h and to reach distances of 400 and 1000 m leaving from an initial speed of 40 km/h at full acceleration were recorded. The results showed the vehicle performance to be more affected by changes in the atmospheric pressure than in the temperature. An average difference of 3 per cent in the time to reach 1000 m, leaving from the speed of 40 km/h at full acceleration, was found between the atmospheric pressures tested, for a fixed temperature.

scholarly journals Evidence for the role of organics in aerosol particle formation under atmospheric conditions

2010 ◽  
Vol 107 (15) ◽  
pp. 6646-6651 ◽  
Author(s):  
A. Metzger ◽  
B. Verheggen ◽  
J. Dommen ◽  
J. Duplissy ◽  
A. S. H. Prevot ◽  
...  
Keyword(s):  
Aerosol Particle ◽  
Particle Formation ◽  
Atmospheric Conditions

Abstract P245: Dry Air Triggers Paroxysmal Atrial Fibrillation in Patients with Implantable Cardioverter Defibrillators

Circulation ◽  
2014 ◽  
Vol 129 (suppl_1) ◽  
Author(s):  
Jennifer Nguyen ◽  
Mark S Link ◽  
Heike Luttmann-Gibson ◽  
Francine Laden ◽  
Joel Schwartz ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Medical Center ◽  
Absolute Humidity ◽  
Barometric Pressure ◽  
Primary Prophylaxis ◽  
Time Of Day ◽  
Weather Data ◽  
Implantable Cardioverter Defibrillators ◽  
Dual Chamber ◽  
Cardioverter Defibrillators

Introduction: Atrial fibrillation (AF) is responsible for substantial morbidity and mortality, yet little is known about the environmental factors that may trigger AF episodes. Weather has been proposed as a potential precipitant of paroxysmal AF. Hypothesis: We assessed the hypothesis that changes in outdoor ambient temperature and outdoor absolute humidity may trigger paroxysmal AF in the following 24 hours. Methods: Patients with dual chamber implantable cardioverter defibrillators (ICDs) living in eastern Massachusetts were enrolled between September 2006 and March 2010 from the Tufts Medical Center Cardiac Arrhythmia Clinic (Boston, Massachusetts) and followed prospectively for episodes of paroxysmal AF lasting at least 30 seconds. Arrhythmias documented by the ICD were reviewed and interpreted by an electrophysiologist masked to exposure. The date and time of AF episodes were linked to hourly weather data measured at Boston Logan International Airport. We examined the hypothesis using a time-stratified case-crossover analysis matched on calendar month, day of week and time of day and adjusted for air pollution and barometric pressure. To reduce the possibility of over-representation of clustered events and to reflect the averaging time of the exposure, incident AF episodes were included in the analysis if at least 24 hours had passed since the previous AF episode. Results: Of 200 patients enrolled, 49 experienced at least one AF episode (n = 328 episodes). After excluding events with missing exposure or covariate information, analyses were confined to 230 AF episodes among 47 patients. The 47 patients with paroxysmal AF were followed for an average of 1.9 years, and 32 (68%) were male, 45 (96%) were Caucasian, the mean age was 67 years, 24 (51%) had a history of prior AF episodes, 27 (57%) had a pre-implantation ejection fraction < 35%, and 29 (62%) received the ICD for primary prophylaxis. Outdoor temperature in the previous 24 hours was not associated with AF (odds ratio (OR) = 1.13; 95% confidence interval (CI): 0.89, 1.43, p = 0.32, per interquartile range (IQR) decrease of 6.3°C). Lower absolute humidity in the previous 24 hours was associated with a higher risk of AF onset (OR = 1.33; 95% CI: 1.02, 1.74, p = 0.04, per IQR decrease of 3.5 g/m 3 ); this risk increased slightly for the previous 3 hours (OR = 1.39; 95% CI: 1.06, 1.82, p = 0.02, per IQR decrease of 3.7 g/m 3 ). Conclusions: In conclusion, drier air was associated with a transiently higher risk of paroxysmal AF in the following 24 hours among patients with dual chamber ICDs.

scholarly journals Anatomy and physiology of phrenic afferent neurons

2017 ◽  
Vol 118 (6) ◽  
pp. 2975-2990 ◽  
Author(s):  
Jayakrishnan Nair ◽  
Kristi A. Streeter ◽  
Sara M. F. Turner ◽  
Michael D. Sunshine ◽  
Donald C. Bolser ◽  
...  
Keyword(s):  
Potential Role ◽  
Large Diameter ◽  
Respiratory Cycle ◽  
Conscious Perception ◽  
Relative Impact ◽  
Afferent Neurons ◽  
Sensory Afferents ◽  
Synaptic Contacts ◽  
Anatomy And Physiology

Large-diameter myelinated phrenic afferents discharge in phase with diaphragm contraction, and smaller diameter fibers discharge across the respiratory cycle. In this article, we review the phrenic afferent literature and highlight areas in need of further study. We conclude that 1) activation of both myelinated and nonmyelinated phrenic sensory afferents can influence respiratory motor output on a breath-by-breath basis; 2) the relative impact of phrenic afferents substantially increases with diaphragm work and fatigue; 3) activation of phrenic afferents has a powerful impact on sympathetic motor outflow, and 4) phrenic afferents contribute to diaphragm somatosensation and the conscious perception of breathing. Much remains to be learned regarding the spinal and supraspinal distribution and synaptic contacts of myelinated and nonmyelinated phrenic afferents. Similarly, very little is known regarding the potential role of phrenic afferent neurons in triggering or modulating expression of respiratory neuroplasticity.

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