Impact of wind speed, air temperature, and soil permeability on gas transport in the upper vadose zone

E. Levintal, M. I. Dragila, N. Weisbrod

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

In high permeability soils, the overall gas flux through the Earth-atmosphere interface can be significantly greater than the diffusive gas flux. Here we focused on the role of atmospheric conditions and porous media properties on convective gas transport mechanisms. Three different experiments quantitatively explored the correlation between media particle size and the development of three gas transport mechanisms: enhanced diffusion, thermal-induced convection, and wind-induced convection. These mechanisms, resulting from the development of thermal gradient and surface wind, were analyzed both independently and in combination. Two types of experiments were carried out: (1) under field conditions, and (2) under highly controlled laboratory conditions using highly-permeable porous media composed of well-defined single-sized spherical particles. Porous media permeability ranged from 3.87×10-10 m2 (sand) up to 2.67×10-6 m2 (large aggregates collected from an agricultural field). In all studies, temperature and wind conditions across the media and at the media-atmosphere interface were monitored. Results show that the magnitudes of thermal- and wind-induced convection were directly related to porous media particle size (and, subsequently, media permeability) given favoring ambient conditions at the media-atmosphere interface. Such ambient conditions were either high diurnal temperature amplitude (~± 10 ᵒC) or high surface wind (~2 m/s measured 10 m above ground). In addition, specific results from the field experiment were used to establish an empirical model that predicts gas transport magnitude as a function of wind speed and media permeability.
Original languageEnglish
Title of host publicationAmerican Geophysical Union, Fall Meeting 2019
StatePublished - 1 Dec 2019
EventAmerican Geophysical Union (AGU) Fall Meeting 2019 - San Francisco , United States
Duration: 9 Dec 201913 Dec 2019
https://www.agu.org/fall-meeting-2019

Conference

ConferenceAmerican Geophysical Union (AGU) Fall Meeting 2019
Country/TerritoryUnited States
CitySan Francisco
Period9/12/1913/12/19
Internet address

Keywords

  • 1843 Land/atmosphere interactions
  • HYDROLOGY
  • 1847 Modeling
  • 1865 Soils
  • 1875 Vadose zone

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