Open AccessStatistical features of aerodynamic effective roughness length over heterogeneous terrain
Author(s) -
Huang Jin,
Zhong Zhong,
Weidong Guo,
Wei Lu
Publication year - 2013
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.62.054204
Subject(s) - roughness length , surface finish , terrain , drag , drag coefficient , surface roughness , planetary boundary layer , stratification (seeds) , materials science , standard deviation , mechanics , boundary layer , meteorology , mathematics , physics , wind speed , statistics , wind profile power law , composite material , seed dormancy , ecology , germination , botany , dormancy , biology
With a new scheme of effective roughness length for heterogeneous terrain, based on the atmospheric boundary layer Monin-Obukhov similarity theory as well as flux and mass conservation principles, the statistical features of effective roughness length and its sensitivity to atmospheric stratification stability and roughness step for three surface category case are investigated. The results show that the effective roughness length is greater than the area-weighted logarithmic average one and the effective drag coefficient is more than 10% greater than the average one in most cases. The effective roughness length is much more sensitive to the roughness step, though it is dependent on the atmospheric stratification stability, and the relative percentage of effective roughness length and the effective drag coefficient will be 4 times and 3 times, respectively, for the double roughness step case. Therefore, the area-weighted average roughness length should be replaced by the effective one when the surface heterogeneity is considered in numerical models, which can represent the integrated effect of heterogeneous terrain.