AuthorsOhtani, Y., Mizoguchi, Y., Watanabe, T., Yasuda, Y.
TitleParameterization of NEP for Gap Filling in a Cool-Temperate Coniferous Forest in Fujiyosida, Japan
JournalJournal of agricultural meteorology
Keywordsday assimilation, eddy covariance flux of CO2, nighttime respiration, parameterization
AbstractThis paper had two aims: 1) appropriate selection of nighttime flux data and 2) data gap filling by parameterization, for long-term CO2 flux monitoring using the eddy covariance method. The study was conducted in a cool temperate coniferous forest on a gently inclined slope. The nighttime CO2 flux, which is representative of ecosystem respiration, was parameterization by air temperature using data with a friction velocity of greater than 0.2 ms-1. Data selection by friction velocity showed that the different tendencies previously reported for complex terrain sites might exert similar effects to nighttime data quality tests on stationarity. For the daytime assimilation, a gross ecosystem assimilation was parameterized by absorbed photosynthetically active radiation (APAR) using the Michaelis-Menten equation, where the saturation and initial constants were further parameterized by air temperature. Daytime gross ecosystem assimilation could be estimated by APAR and mean air temperature (Ta) regardless of the time of year.