A detailed analysis of the predictability of observed Monin-Obukhov (M
O) similarity within the near-ground region of near-neutral to moderat
ely convective atmospheric boundary layers (ABL) from large-eddy simul
ation (LES) fields is reported in this work. High-resolution LES predi
ctions of means, variances, budgets of turbulent kinetic energy and te
mperature variance, and the velocity and temperature spectra from thre
e ABL states (-z(i)/L = 0.44, 3 and 8) are analysed under MO scaling.
The resolution in the near-ground region is increased by using 'nested
meshes.' For the close-to-neutral case (-z(i)/L = 0.44) the relative
roles of grid resolution and subgrid-scale (SGS) parameterization on t
he predictability of MO-similarity are also studied. The simulated tem
perature field is found to satisfy the MO hypothesis and agree well wi
th observations. The simulated velocity field, on the other hand, show
s significant departures. Except for the horizontal variance, MO scale
s are the appropriate normalizing scales for the near-ground-layer sta
tistics. However, the LES suggest that the boundary layer depth z(i) h
as an 'indirect' influence on all near-ground-layer variables except t
emperature, and the LES-predicted MO-scaled variables exhibit a functi
onal dependence on both z/L and z/z(i). The simulated two-dimensional
spectra of velocity and temperature fluctuations, however, suggest tha
t while large scales deviate from MO-similarity, inertial subrange sca
les are MO-similar. Discrepancies with field observations raise import
ant questions of the non-dimensional depth z/z(i) over which MO-simila
rity holds for a particular variable. Surface-layer field studies gene
rally do not document z(i). It is also not clear to what extent these
discrepancies are due to approximations made in LES. Measurements are
needed designed specifically for comparing with LES predictions.