FIG. 2: August-October climatological mean fields:
(a) tropospheric vertical wind shear (200 minus
850 mb flow with a contour interval of 3 m s^{-1}, with
shear values less than 9 m s^{-1} shaded); (b) 200 mb
streamlines and zonal wind speeds (contour interval of 3 m s^{-1}, with
positive (negative) values solid (dashed) and any easterly component is shaded);
(c) 850 mb streamlines and zonal wind speeds (contour interval of 2 m
s^{-1}, with positive (negative) values solid (dashed) and any easterly
component greater than 6 m s^{-1} is shaded).
Climatology is calculated from the 1979-1995 base period monthly means.