Effects of water vapor dilution on trace gas flux, and practical correction methods

• HARAZONO Yoshinobu

  International Arctic Research Center, University of Alaska Fairbanks Graduate School of Life and Environmental Sciences, Osaka Prefecture University

• IWATA Hiroki

  International Arctic Research Center, University of Alaska Fairbanks Graduate School of Agriculture, Kyoto University Faculty of Science, Sinshu University

• SAKABE Ayaka

  Graduate School of Agriculture, Kyoto University

• UEYAMA Masahito

  Graduate School of Life and Environmental Sciences, Osaka Prefecture University

• TAKAHASHI Kenshi

  Research Institute for Sustainable Humanosphere, Kyoto University

• NAGANO Hirohiko

  International Arctic Research Center, University of Alaska Fairbanks

• NAKAI Taro

  International Arctic Research Center, University of Alaska Fairbanks Hydrospheric Atmospheric Research Center, Nagoya University

• KOSUGI Yoshiko

  Graduate School of Agriculture, Kyoto University

抄録

The effect of water vapor dilution on CH₄ flux was examined here using dynamic chamber measurements at the forest floor of a black spruce forest in interior Alaska. CH₄ and CO₂ concentrations were differently diluted by increased water vapor in each chamber. After correction for water vapor dilution was applied, source (positive) CH₄ flux was enhanced, whereas sink (negative) flux was reduced, and magnitude changed depending on the condition of water vapor.<br>　Several methods were examined to practically correct water vapor dilution for fluxes previously measured. Numerical correction for all data sampled at high frequency intervals (DAE-method) is highly recommended. Water vapor dilution correction for ensemble-averaged data (SA-method) is also applicable, though not recommended in case of long-term average data for accurate flux determination, especially for data obtained at irregular source strength plots. When evapotranspiration is measured in parallel to CH₄ flux, the removal of the water vapor increment due to evapotranspiration in the chamber is another option for correction (HCE-method). This method resulted in similar accuracy to the DAE-method, as long as continuously sampled data were applicable.<br>　The application of the correction for water vapor dilution to previous tower-based flux data (measured over a wet sedge tundra in Barrow throughout the month of August, 2000) also resulted in an increase in source (positive) flux of 6.6% on average.<br>　This study concludes that either accurate flux must be determined using mixing ratio, or a water vapor dilution correction must be applied using simultaneously measured water vapor and trace gases.

収録刊行物

• 農業気象

  農業気象 71 (2), 65-76, 2015

  日本農業気象学会

キーワード

• CH₄ flux
• Correction methods
• Dynamic chamber
• H₂O dilution
• Trace gas

詳細情報

• CRID: 1390282679645576576
• NII論文ID: 130005075874
• NII書誌ID: AN00200732
• DOI: 10.2480/agrmet.d-14-00003
• ISSN: 18810136
• ISSN: 00218588
• NDL書誌ID: 026447863
• Web Site: http://id.ndl.go.jp/bib/026447863
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I026447863
• Web Site: https://www.jstage.jst.go.jp/article/agrmet/71/2/71_D-14-00003/_pdf
• 本文言語コード: en
• データソース種別:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• 抄録ライセンスフラグ: 使用不可