Abstract: Detrending correction and sonic anemometer tilt correction were made to modify the raw time series measured from eddy covariance system in broad-leaved Korean pine forest of Changbai Mountains during the growing season of 2003,and the impact of different correction methods on CO₂ flux was analyzed quantificationally.The results showed that the forest CO₂ flux during growing season was overestimated when calculated from raw time series.The ratio of correction to origin flux (Fcraw) was 1.6% and 1.8% for linear and nonlinear detrend,respectively,which suggested that there was little difference between these two detrending methods.It was 3.7% and 4.7% for the planar fit coordinate transforming (PF) correction and the streamline coordinate system transforming (ST) correction,respectively,suggesting that there was a clear difference between these two sonic anemometer tilt correction methods.When detrended time series used,it was 5.5 % and 4.6% for ST correction and PF correction,respectively.It was recommended that raw time series should be corrected synthetically with linear detrend method and PF method.

Key words: Time series, Carbon cycle, Detrending correction, Sonic anemometer tilt correction