Persistent wind-induced enhancement of diffusive CO<sub>2</sub>transport in a mountain forest snowpack

Bowling, David R.; Massman, W. J.

doi:10.1029/2011jg001722

Cited by 100 publications

(119 citation statements)

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“…This influence is referred to as turbulence-induced "pressure pumping" and has attracted great interest in recent years [8,[12][13][14][15][16][17][18][19][20]. Results from present research suggest that soil gas transport is enhanced up to 100% by air pressure fluctuations induced by airflow, dependent on the investigated soil [18,19,21]. This can be an important driver for the soil-atmosphere exchange rates of greenhouse gases.…”

Section: Introductionmentioning

confidence: 73%

Analysis of Air Pressure Fluctuations and Topsoil Gas Concentrations within a Scots Pine Forest

et al. 2016

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High-precision differential air pressure measurements were conducted in the below-canopy space of a Scots pine forest and in the forest soil to investigate small air pressure fluctuations and their effect on soil gas flux. In addition to air pressure measurements, tracer gas concentration in the soil and airflow characteristics above and below the canopy were measured. Results suggest that air pressure fluctuations in the frequency range of 0.01 Hz-0.1 Hz are strongly dependent on abovecanopy wind speed. While amplitudes of the observed air pressure fluctuations (<10 Pa) increase significantly with increasing above-canopy wind speed, the periods decrease significantly with increasing above-canopy wind speed. These air pressure fluctuations are associated with the pressure-pumping effect in the soil. A pressure-pumping coefficient was defined, which describes the strength of the pressure-pumping effect. During the measurement period, pressure-pumping coefficients up to 0.44 Pa·s −1 were found. The dependence of the pressure-pumping coefficient on mean above-canopy wind speed can be described well with a polynomial fit of second degree. The knowledge of this relation simplifies the quantification of the pressure-pumping effect in a Scots pine forest considerably, since only the mean above-canopy wind speed has to be measured. In addition, empirical modeling revealed that the pressure-pumping coefficient explains the largest fraction of the variance of tracer gas concentration in the topsoil.

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Section: Introductionmentioning

confidence: 73%

Analysis of Air Pressure Fluctuations and Topsoil Gas Concentrations within a Scots Pine Forest

et al. 2016

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“…The applicability of the Keeling plot has been proven in environments where the mixing process between air masses occurs by bulk advection (Bowling and Massman, 2011;Buchmann et al, 1998;Zobitz et al, 2006). However, the assumption of the model for diffusive environments (e.g., from the air-filled porosity of soils to the open atmosphere) could lead to misinterpretation relative to the isotopic ratio of the source (Risk and Kellman, 2008;Nickerson and Risk, 2009).…”

Section: Discussionmentioning

confidence: 99%

“…The δ 13 C of CO 2 (δ 13 CO 2 ) in air has been traditionally studied to identify the characteristic δ 13 CO 2 of ecosystem respiration and the contribution of different biotic or abiotic sources (Yakir and Sternberg, 2000;Pataki et al, 2003;Hemming et al, 2005). The isotopic ratio characterizes the chemical changes undergone by the gas, introducing identifiers for the source of production and transport mechanisms (Maseyk et al, 2009;Kayler et al, 2010;Moyes et al, 2010;Bowling and Massman 2011;Shanhun et al, 2012;Garcia-Anton et al, 2014a). In studies carried out in natural environments, the δ 13 CO 2 of the source contributing to enhance the CO 2 concentration in air can be easily obtained by mass-balance estimations such as the Keeling approach (Keeling, 1958;Keeling, 1961).…”

Section: Introductionmentioning

confidence: 99%

Abiotic and seasonal control of soil-produced CO2 efflux in karstic ecosystems located in Oceanic and Mediterranean climates

Garcia-Anton

Cuezva

Fernández-Cortés

et al. 2017

Atmospheric Environment

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This study characterizes the processes involved in seasonal CO 2 exchange between soils and shallow underground systems and explores the contribution of the different biotic and abiotic sources as a function of changing weather conditions. We spatially and temporally investigated five karstic caves across the Iberian Peninsula, which presented different microclimatic, geologic and geomorphologic features. The locations present Mediterranean and Oceanic climates. Spot air sampling of CO 2 (g) and δ 13 CO 2 in the caves, soils and outside atmospheric air was periodically conducted. The isotopic ratio of the source contribution enhancing the CO 2 concentration was calculated using the Keeling model. We compared the isotopic ratio of the source in the soil (δ 13 C s -soil) with that in the soil-underground system (δ 13 C s -system).Although the studied field sites have different features, we found common seasonal trends in their values, which suggests a climatic control over the soil air CO 2 and the δ 13 CO 2 of the sources of CO 2 in the soil (δ 13 C s -soil) and the system (δ 13 C s -system). The roots respiration and soil organic matter degradation are the main source of CO 2 in underground environments, and the inlet of the gas is mainly driven by diffusion and advection. Drier and warmer conditions enhance soil-exterior CO 2 interchange, reducing the CO 2 concentration and increasing the δ 13 CO 2 of the soil air. Moreover, the isotopic ratio of the source of CO 2 in both the soil and the system tends to heavier values throughout the dry and warm season.We conclude that seasonal variations of soil CO 2 concentration and its 13 C/ 12 C isotopic ratio are mainly regulated by thermo-hygrometric conditions. In cold and wet seasons, the increase of soil moisture reduces soil diffusivity and allows the storage of CO 2 in the subsoil. During dry and warm seasons, the evaporation of soil water favours diffusive and advective transport of soil-derived CO 2 to the atmosphere. The soil CO 2 diffusion is enough important during this season to modify the isotopic ratio of soil produced CO 2 (3-6‰ heavier). Drought induces release of CO 2 with an isotopic ratio heavier than produced by organic sources. Consequently, climatic conditions drive abiotic processes that turn regulate a seasonal storage of soilproduced CO 2 within soil and underground systems. The results here obtained imply that abiotic emissions of soil-produced CO 2 must be an inherent consequence of droughts, which intensification has been forecasted at global scale in the next 100 years.

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“…Ice-atmosphere gas exchange depends on the differential partial pressure of gases between brine and the atmosphere, wind speed, ice microstructure and snow properties [Delille, 2006;Heinesch et al, 2009;Papakyriakou and Miller, 2011;Bowling and Massman, 2011]. When present, snow can act as an intermediate reservoir for gas until wind speed exceeds a given threshold [Bowling and Massman, 2011;Papakyriakou and Miller, 2011] while, when absent, brine-atmosphere or melt pondatmosphere gas exchanges may occur [Semiletov et al, 2004]. The formation of superimposed ice impedes sea ice-atmosphere gas exchanges [Nomura et al, 2010].…”

Section: Gas Tracersmentioning

confidence: 99%

Role of sea ice in global biogeochemical cycles: emerging views and challenges

Vancoppenolle

Meiners

Michel

et al. 2013

Quaternary Science Reviews

217

215

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International audienceObservations from the last decade suggest an important role of sea ice in the global biogeochemical cycles, promoted by (i) active biological and chemical processes within the sea ice; (ii) fluid and gas exchanges at the sea ice interface through an often permeable sea ice cover; and (iii) tight physical, biological and chemical interactions between the sea ice, the ocean and the atmosphere. Photosynthetic micro-organisms in sea ice thrive in liquid brine inclusions encased in a pure ice matrix, where they find suitable light and nutrient levels. They extend the production season, provide a winter and early spring food source, and contribute to organic carbon export to depth. Under-ice and ice edge phytoplankton blooms occur when ice retreats, favoured by increasing light, stratification, and by the release of material into the water column. In particular, the release of iron - highly concentrated in sea ice - could have large effects in the iron-limited Southern Ocean. The export of inorganic carbon transport by brine sinking below the mixed layer, calcium carbonate precipitation in sea ice, as well as active ice-atmosphere carbon dioxide (CO₂) fluxes, could play a central role in the marine carbon cycle. Sea ice processes could also significantly contribute to the sulphur cycle through the large production by ice algae of dimethylsulfoniopropionate (DMSP), the precursor of sulphate aerosols, which as cloud condensation nuclei have a potential cooling effect on the planet. Finally, the sea ice zone supports significant ocean-atmosphere methane (CH₄) fluxes, while saline ice surfaces activate springtime atmospheric bromine chemistry, setting ground for tropospheric ozone depletion events observed near both poles. All these mechanisms are generally known, but neither precisely understood nor quantified at large scales. As polar regions are rapidly changing, understanding the large-scale polar marine biogeochemical processes and their future evolution is of high priority. Earth system models should in this context prove essential, but they currently represent sea ice as biologically and chemically inert. Palaeoclimatic proxies are also relevant, in particular the sea ice proxies, inferring past sea ice conditions from glacial and marine sediment core records and providing analogues for future changes. Being highly constrained by marine biogeochemistry, sea ice proxies would not only contribute to but also benefit from a better understanding of polar marine biogeochemical cycles

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Persistent wind-induced enhancement of diffusive CO₂transport in a mountain forest snowpack

Cited by 100 publications

References 74 publications

Analysis of Air Pressure Fluctuations and Topsoil Gas Concentrations within a Scots Pine Forest

Analysis of Air Pressure Fluctuations and Topsoil Gas Concentrations within a Scots Pine Forest

Abiotic and seasonal control of soil-produced CO2 efflux in karstic ecosystems located in Oceanic and Mediterranean climates

Role of sea ice in global biogeochemical cycles: emerging views and challenges

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Persistent wind-induced enhancement of diffusive CO2transport in a mountain forest snowpack

Cited by 100 publications

References 74 publications

Analysis of Air Pressure Fluctuations and Topsoil Gas Concentrations within a Scots Pine Forest

Analysis of Air Pressure Fluctuations and Topsoil Gas Concentrations within a Scots Pine Forest

Abiotic and seasonal control of soil-produced CO2 efflux in karstic ecosystems located in Oceanic and Mediterranean climates

Role of sea ice in global biogeochemical cycles: emerging views and challenges

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Persistent wind-induced enhancement of diffusive CO₂transport in a mountain forest snowpack