Effects of Coordinate Rotation on Eddy Correlation Measurements over a Complex Terrain

Effects of coordinate rotation according to the incident angle of the mean flow over a complex terrain on the fluxes are tested using the turbulence measurements with a 3-D sonic anemometer and an open path CO2·H2O fluctuation meter. Root mean square of the differences of the turbulent fluxes before and after the coordinate rotation divided by the mean flux values are less than 30% for sensible and latent heat fluxes for incident angles less than 10 degrees. However, the errors in the CO2 flux become larger than other scalar quantities. The errors in the momentum flux are the largest as expected and become as large as 80% at an angle of 10 degrees. σw/u* is expressed as a function of (z-d)/L with less scatter when the coordinate rotation is applied.