The atmospheric surface layer - Turbulence in the Atmosphere - page 230

Figure 10.6 Replots of some of the σ v data in Fig. 10.5 . Lower: Data at fixed
z (here 5.7 m) from three different cases appear to show a local-free-convection
regime like that for σ w , Figure 10.5 . Upper: Data from the three heights in these
cases suggest instead that σ v depends only weakly on z . If so, the trend in the lower
panel is likely due to the influence of boundary-layer depth, expressed through w ∗ ,
Eq. (10.42) .From Wyngaard ( 1988 ).

Figure 10.7 Time histories of wind variances in the convective surface lay er.
Sho rtly after 1100 local time z i grew rapidly; the horiz onta l wind variances u 2
and v 2 increased as well, as predicted by w ∗ scaling, but w 2 , being M-O similar,

did not. From Banta ( 1985 ).