標題: | Effects of water vapor dilution on trace gas flux, and practical correction methods |
作者: | Harazono, Yoshinobu Iwata, Hiroki Sakabe, Ayaka Ueyama, Masahito Takahashi, Kenshi Nagano, Hirohiko TARO NAKAI Kosugi, Yoshiko |
關鍵字: | CH4 flux; Correction methods; Dynamic chamber; H2O dilution; Trace gas |
公開日期: | 2015 |
出版社: | SOC AGRICULTURAL METEOROLOGY JAPAN |
來源出版物: | Journal of Agricultural Meteorology |
摘要: | © 2015, Society of Agricultural Meteorology of Japan. All rights reserved. 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. 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 evapo-transpiration 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. 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. 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. |
URI: | http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000356203900002&KeyUID=WOS:000356203900002 https://scholars.lib.ntu.edu.tw/handle/123456789/403565 |
ISSN: | 00218588 |
DOI: | 10.2480/agrmet.D-14-00003 |
顯示於: | 森林環境暨資源學系
|