Abstract:

Based on the eddy correlation observation data of the 70-m tower on the east bank of Poyang lake from July 1, 2013 to June 30, 2014, the surface zero plane displacement and roughness length were calculated with the Martano method and TVM method (Temperature Variance Method). The friction velocity calculated by substituting the wind profile relation based on Monin-Obukhov similarity theory was compared with the observation for verifying their consistency. The results show that the normalized fitted curves of velocity and temperature standard deviations show a similar trend with the theoretical curves given by Panosky et al. and Tillman. The results calculated with the Martano method vary greatly with the season, and the roughness in spring and summer is 6.3 times larger than that in autumn and winter. The zero plane displacement and roughness for land surface are 2 times and 10 times larger than those for lake surface, respectively. Martano method is more sensitive to the season and direction relative to the TVM method. The friction velocity estimated with the Martano method causes about 9.9% overestimation for the friction velocity, while that with the TVM method results in an overestimation of about 32.8%. On the whole, it can be seen that the friction velocity calculated by the Martano method is better consistent with the observed value.

Key words: Aerodynamic roughness, Zero plane displacement, Complex underlying surface