Fig. 3. High frequency windspeed standard deviation field for 965 mb (a) FLAT, (b) OROG, (c) SURF and (d) FULL. CI=1 m s^-1 in (a)-(d). Values > 8 m s^-1 shaded in (a)-(d). Zero line omitted. Orographic areas above 965 mb blackened in (b), (c) and (d).