Conversion of profile difference quotients to true gradients at the geometric mean height in the surface layer

Theoretical profiles of wind speed and air temperature can provide synthetic measurements at discrete levels which may be compared with actual field measurements. In addition to wind and temperature gradients at any height, profile theory permits us to determine the difference quotients from measurements at discrete levels. It is shown that corrections are required to obtain the gradients at the geometric mean height of the two discrete levels of measurement. The correction factor depends on the measurement height and spacing, profile structure, surface roughness and the measured Richardson number. The correction can be reduced by close spacing of the measurement levels.