B33A-0632
Why we need to estimate the sampling uncertainty of eddy covariance flux measurement?
Wednesday, 16 December 2015
Poster Hall (Moscone South)
Wonsik Kim, NIAES National Institute for Agro-Environmental Sciences, Tsukuba, Japan
Abstract:
Fruitful studies on exchanges of energy, water and carbon dioxide between the atmosphere and terrestrial ecosystem has been produced under a global network (http://fluxnet.ornl.gov). The exchange is defined by a flux, and in traditional the flux is estimated with eddy covariance (EC) method as a mean flux F for 30-min or 1-hr, because no techniques have been established for a direct measurement of a momentary flux itself. Therefore, the exchange analysis with F is to paid attention to estimations of spatial or temporal mean, because the exchange estimated by arithmetic mean Fa might be inappropriate in terms of the sample F used in this averaging having nonidentical inherent quality within one another in accordance with different micrometeorological and ecophysiological conditions while those are measured by the same instruments. To overcome this issue, we propose the weighted mean Fw using a relative sampling uncertainty ε estimated by a sampling F and its uncertainty, and introduce Fw performance tested with EC measurements for various sites.