scholarly journals Impact of atmospheric pressure variations on methane ebullition and lake turbidity during ice‐cover

2021 ◽  
Author(s):  
Kai Zhao ◽  
Edmund W. Tedford ◽  
Marjan Zare ◽  
Gregory A. Lawrence
Keyword(s):  
Atmospheric Pressure ◽  
Ice Cover ◽  
Methane Ebullition

scholarly journals Modeling the impediment of methane ebullition bubbles by seasonal lake ice

2014 ◽  
Vol 11 (23) ◽  
pp. 6791-6811 ◽  
Author(s):  
S. Greene ◽  
K. M. Walter Anthony ◽  
D. Archer ◽  
A. Sepulveda-Jauregui ◽  
K. Martinez-Cruz
Keyword(s):  
Growth Rate ◽  
Lake Water ◽  
Ice Cover ◽  
Controlling Factors ◽  
Ch4 Emission ◽  
Lake Ice ◽  
Ch4 Emissions ◽  
Interior Alaska ◽  
Methane Ebullition ◽  
Significant Flux

Abstract. Microbial methane (CH4) ebullition (bubbling) from anoxic lake sediments comprises a globally significant flux to the atmosphere, but ebullition bubbles in temperate and polar lakes can be trapped by winter ice cover and later released during spring thaw. This "ice-bubble storage" (IBS) constitutes a novel mode of CH4 emission. Before bubbles are encapsulated by downward-growing ice, some of their CH4 dissolves into the lake water, where it may be subject to oxidation. We present field characterization and a model of the annual CH4 cycle in Goldstream Lake, a thermokarst (thaw) lake in interior Alaska. We find that summertime ebullition dominates annual CH4 emissions to the atmosphere. Eighty percent of CH4 in bubbles trapped by ice dissolves into the lake water column in winter, and about half of that is oxidized. The ice growth rate and the magnitude of the CH4 ebullition flux are important controlling factors of bubble dissolution. Seven percent of annual ebullition CH4 is trapped as IBS and later emitted as ice melts. In a future warmer climate, there will likely be less seasonal ice cover, less IBS, less CH4 dissolution from trapped bubbles, and greater CH4 emissions from northern lakes.

scholarly journals Falling atmospheric pressure as a trigger for methane ebullition from peatland

2007 ◽  
Vol 21 (2) ◽  
pp. n/a-n/a ◽  
Author(s):  
T. Tokida ◽  
T. Miyazaki ◽  
M. Mizoguchi ◽  
O. Nagata ◽  
F. Takakai ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Methane Ebullition

scholarly journals Classification of surface atmospheric pressure fields in the Laptev and East Siberian seas

2021 ◽  
Vol 67 (4) ◽  
pp. 394-405
Author(s):  
V. S. Porubaev ◽  
L. N. Dyment
Keyword(s):  
Surface Pressure ◽  
Atmospheric Pressure ◽  
Ice Cover ◽  
The Arctic ◽  
Wind Fields ◽  
Arctic Seas ◽  
Pressure Fields ◽  
Ice Drift ◽  
Waves And Currents

The need for classifying surface atmospheric pressure fields over the Arctic seas arose as a method was being developed for predicting the characteristics of discontinuities (leads) in the sea ice cover. Wind, which is determined by the atmospheric pressure field, acts on the ice cover and causes it to drift. Leads are formed in the ice cover due to the irregularity of ice drift. Ice drift can be caused by several factors, such as skewed sea level, tidal waves and currents. However, the main cause of ice drift in the Arctic seas is wind. Each typical field of surface atmospheric pressure corresponds to a certain field of leads in the ice cover. This makes it possible to predict the characteristics of leads in the ice cover by selecting fields similar to predictive fields of atmospheric pressure based on archived data.The variety of atmospheric pressure fields makes it difficult to find an analogue to a given field by simply going through all the corresponding data available in the electronic archive. Classification of atmospheric pressure fields makes it possible to simplify the process of selecting an analogue.To develop the classification, we used daily surface pressure maps at 00 hours GMT for the cold seasons (from mid- October to the end of May) 2016–2021. The atmospheric pressure fields, which were similar in configuration, and hence the wind fields, belonged to the same type. In total, 27 types were identified, applicable both to the Laptev Sea and the East Siberian Sea. Within one type, a division into subtypes was made, depending on the speed of the geostrophic wind.The wind intensity was estimated by the number of isobars multiples of 5 mb on the surface atmospheric pressure map. All the surface pressure fields observed over the waters of the Laptev and East Siberian Seas over the past 5 years have been assigned to one of the types identified using cluster analysis. Each type of atmospheric pressure within the framework of the forecasting method being developed is supposed to correspond to a field of discontinuities in the ice cover.

scholarly journals Modeling the impediment of methane ebullition bubbles by seasonal lake ice

2014 ◽  
Vol 11 (7) ◽  
pp. 10863-10916 ◽  
Author(s):  
S. Greene ◽  
K. M. Walter Anthony ◽  
D. Archer ◽  
A. Sepulveda-Jauregui ◽  
K. Martinez-Cruz
Keyword(s):  
Growth Rate ◽  
Lake Water ◽  
Ice Cover ◽  
Controlling Factors ◽  
Ch4 Emission ◽  
Lake Ice ◽  
Ch4 Emissions ◽  
Interior Alaska ◽  
Methane Ebullition ◽  
Significant Flux

Abstract. Microbial methane (CH4) ebullition (bubbling) from anoxic lake sediments comprises a globally significant flux to the atmosphere, but ebullition bubbles in temperate and polar lakes can be trapped by winter ice cover and later released during spring thaw. This "ice-bubble storage" (IBS) constitutes a novel mode of CH4 emission. Before bubbles are encapsulated by downward-growing ice, some of their CH4 dissolves into the lake water, where it may be subject to oxidation. We present field characterization and a model of the annual CH4 cycle in Goldstream Lake, a thermokarst (thaw) lake in interior Alaska. We find that summertime ebullition dominates annual CH4 emissions to the atmosphere. Eighty percent of CH4 in bubbles trapped by ice dissolves into the lake water column in winter, and about half of that is oxidized. The ice growth rate and the magnitude of the CH4 ebullition flux are important controlling factors of bubble dissolution. Seven percent of annual ebullition CH4 is trapped as IBS and later emitted as ice melts. In a future warmer climate, there will likely be less seasonal ice cover, less IBS, less CH4 dissolution from trapped bubbles, and greater CH4 emissions from northern lakes.

scholarly journals Multiyear methane ebullition measurements from water and bare peat surfaces of a patterned boreal bog

2019 ◽  
Author(s):  
Elisa Männistö ◽  
Aino Korrensalo ◽  
Pavel Alekseychik ◽  
Ivan Mammarella ◽  
Olli Peltola ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Open Water ◽  
Co2 Concentration ◽  
Growing Seasons ◽  
Wetland Complex ◽  
Ecosystem Level ◽  
Trapped Gas ◽  
Bare Peat ◽  
Carbon Dioxide Co2 ◽  
Methane Ebullition

Abstract. We measured methane ebullition from a patterned boreal bog situated in the Siikaneva wetland complex in southern Finland. Measurements were conducted on water (W) and bare peat surfaces (BP) in three growing seasons 2014–2016 using floating gas traps. The volume of the trapped gas was measured weekly, and methane and carbon dioxide (CO2) concentrations of bubbles were analyzed from fresh bubble samples collected separately. We applied a mixed effects model to quantify the effect of the environmental controlling factors on the ebullition. Ebullition was higher from W than from BP, and more bubbles were released from open water (OW) than from water's edge (EW). On average, ebullition rate was the highest in the wettest year 2016 and ranged between 0–253 mg m−2 d−1, 0–147 mg m−2 d−1 and 0–186 mg m−2 d−1 in 2014, 2015 and 2016, respectively. Ebullition increased together with increasing peat temperature, weekly air temperature sum and atmospheric pressure, and decreasing water table (WT). Methane concentration in the bubbles released from W was 15–20 times higher and from BP 10 times higher than their CO2 concentration. The proportion of ebullition fluxes upscaled to ecosystem level for the peak season was 2–8 % and 2–5 % of the total flux measured with eddy covariance technique and with chambers and gas traps, respectively. Thus, the contribution of methane ebullition from wet non-vegetated surfaces of the bog to the total ecosystem-scale methane emission appeared to be small.

scholarly journals Changes of the ice cover and variation of atmospheric pressure field in arctic

ScienceRise ◽  
2016 ◽  
Vol 7 (1 (24)) ◽  
pp. 22
Author(s):  
Александр Вадимович Холопцев ◽  
Нина Константиновна Кононова
Keyword(s):  
Atmospheric Pressure ◽  
Pressure Field ◽  
Ice Cover

scholarly journals The Impact of the Siberian High and Aleutian Low on the Sea-Ice Cover of the Sea of Okhotsk

1990 ◽  
Vol 14 ◽  
pp. 226-229 ◽  
Author(s):  
Claire L. Parkinson
Keyword(s):  
Sea Ice ◽  
Atmospheric Pressure ◽  
Sea Of Okhotsk ◽  
Ice Cover ◽  
Passive Microwave ◽  
Aleutian Low ◽  
Siberian High ◽  
The Sea Of Okhotsk ◽  
Ice Conditions ◽  
The Impact

Comparison of monthly averaged sea-ice distributions in the Sea of Okhotsk with atmospheric pressure data during the four winters having passive-microwave sea-ice coverage from the Nimbus 5 satellite, 1973–76, revealed a strong apparent relationship between the extent of the sea-ice cover and the influence of the Siberian High atmospheric pressure system. Examination of data for the years 1978–86, having passive-microwave coverage from the Nimbus 7 satellite, reveals that the strong correspondence found for 1973–76 between Okhotsk sea-ice extents and the Siberian High was not maintained in the 1978–86 period. A weaker correspondence continued, however, between the sea ice and the combined Siberian High/Aleutian Low system. A Siberian High/Aleutian Low index was created, and the correlation coefficient between that index and sea-ice extents in the midwinter month of February is 0.97 for the 1973–76 period and 0.52 for the 1978–86 period. Primary reasons for the lack of a consistently strong monthly averaged ice/atmosphere correspondence are: the various oceanographic influences on the sea-ice cover, the failure of monthly averages to reflect fully the important shorter-term interactions between the ice and the atmosphere, and the fact that ice conditions in one month are influenced by ice conditions in previous months.

scholarly journals The Impact of the Siberian High and Aleutian Low on the Sea-Ice Cover of the Sea of Okhotsk

1990 ◽  
Vol 14 ◽  
pp. 226-229 ◽  
Author(s):  
Claire L. Parkinson
Keyword(s):  
Sea Ice ◽  
Atmospheric Pressure ◽  
Sea Of Okhotsk ◽  
Ice Cover ◽  
Passive Microwave ◽  
Aleutian Low ◽  
Siberian High ◽  
The Sea Of Okhotsk ◽  
Ice Conditions ◽  
The Impact

Comparison of monthly averaged sea-ice distributions in the Sea of Okhotsk with atmospheric pressure data during the four winters having passive-microwave sea-ice coverage from the Nimbus 5 satellite, 1973–76, revealed a strong apparent relationship between the extent of the sea-ice cover and the influence of the Siberian High atmospheric pressure system. Examination of data for the years 1978–86, having passive-microwave coverage from the Nimbus 7 satellite, reveals that the strong correspondence found for 1973–76 between Okhotsk sea-ice extents and the Siberian High was not maintained in the 1978–86 period. A weaker correspondence continued, however, between the sea ice and the combined Siberian High/Aleutian Low system. A Siberian High/Aleutian Low index was created, and the correlation coefficient between that index and sea-ice extents in the midwinter month of February is 0.97 for the 1973–76 period and 0.52 for the 1978–86 period. Primary reasons for the lack of a consistently strong monthly averaged ice/atmosphere correspondence are: the various oceanographic influences on the sea-ice cover, the failure of monthly averages to reflect fully the important shorter-term interactions between the ice and the atmosphere, and the fact that ice conditions in one month are influenced by ice conditions in previous months.

A High-Voltage Terminal for a Field-Emission Gun

1972 ◽  
Vol 30 ◽  
pp. 428-429
Author(s):  
N. F. Ziegler
Keyword(s):  
Field Emission ◽  
High Voltage ◽  
Atmospheric Pressure ◽  
Power Supplies ◽  
High Coherence

A high-voltage terminal has been constructed for housing the various power supplies and metering circuits required by the field-emission gun (described elsewhere in these Proceedings) for the high-coherence microscope. The terminal is cylindrical in shape having a diameter of 14 inches and a length of 24 inches. It is completely enclosed by an aluminum housing filled with Freon-12 gas at essentially atmospheric pressure. The potential of the terminal relative to ground is, of course, equal to the accelerating potential of the microscope, which in the present case, is 150 kilovolts maximum.

Electron microscope characterization of MOCVD-grown gap layers on Si

1986 ◽  
Vol 44 ◽  
pp. 724-725
Author(s):  
K.M. Jones ◽  
M.M. Al-Jassim ◽  
J.M. Olson
Keyword(s):  
Atmospheric Pressure ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Organic Chemical ◽  
Lattice Match ◽  
Si Substrates ◽  
Metal Organic ◽  
Good Lattice ◽  
Antiphase Domains

The epitaxial growth of III-V semiconductors on Si for integrated optoelectronic applications is currently of great interest. GaP, with a lattice constant close to that of Si, is an attractive buffer between Si and, for example, GaAsP. In spite of the good lattice match, the growth of device quality GaP on Si is not without difficulty. The formation of antiphase domains, the difficulty in cleaning the Si substrates prior to growth, and the poor layer morphology are some of the problems encountered. In this work, the structural perfection of GaP layers was investigated as a function of several process variables including growth rate and temperature, and Si substrate orientation. The GaP layers were grown in an atmospheric pressure metal organic chemical vapour deposition (MOCVD) system using trimethylgallium and phosphine in H2. The Si substrates orientations used were (100), 2° off (100) towards (110), (111) and (211).

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