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Fig. 4.13 Diurnal variation of the standard deviation of the vertical wind component (sigma w) in
three different heights above ground (40, 100, and 160 m) during an undisturbed cloudless weather
situation in summer 2005. The half-hourly data are from SODAR measurements near the Paris
airport Charles de Gaulle
et al. 1993 ; Lokoshchenko 2002 ), in Hannover (Germany, Emeis and Türk 2004 ),
Toronto (Canada) for the CBL (Melling and List 1980 ), and Linz (Austria, Emeis
et al. 2007b ). Mean seasonal profiles of wind speed, standard deviation of the verti-
cal velocity and turbulence intensity from SODAR measurements in three cities of
different size, Moscow, Hannover, and Linz, have been recently compared to analyt-
ical descriptions of the wind profile for the Prandtl and Ekman layer in Emeis et al.
( 2007b ). We will excerpt from this review in the next paragraphs. Comparable stud-
ies on wind profiles in the urban boundary layer have been written by Lokoshchenko
et al. ( 2007 , 2009 ) and Kallistratova et al. ( 2009 ) as well.
Mean Urban Wind Profiles
Mean monthly wind profiles observed in Hannover in April 2003 together with
theoretically derived stability-dependent logarithmic wind profiles are shown as an
example in Fig. 4.15 . April is representative for spring in Hannover. Nocturnal wind
speeds are on average higher than daytime wind speeds except for heights below
125m above ground, because the atmosphere is stabler at night and less vertical
momentum exchange takes place. The monthly mean is computed from 30 min-
mean profiles, which are complete up to at least 210 m. Above this height, the data
availability decreases and is about 20% at 500 m height.
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