Wieringa (1980)
has argued that instrument boxes at the 5.66-, 11.1 and 22.6-m tower levels in the 1968 Kansas experiments caused flow distortion at the sonic anemometers upwind of these boxes. Specifically, he claims that mean upward flow deviation and horizontal flow stagnation were induced at the sonic locations. According to Wieringa (p. 420), this flow distortion '. . . has an effect similar to the result of instrumental misalignment, viz., a severe tilt error in the stress measured in natural coordinates', Using a 2.4 m diameter sphere to represent the boxes, Wieringa estimates the mean upward flow deviation and horizontal stagnation from a potential flow calculation. He then uses a 'tilt correction' to calculate that the stresses and heat fluxes measured by the sonic anemometers were low, being about 0.78 and 0.93, respectively, of the values in the undisturbed flow. Noting that in the original Kansas data analysis (Haugen et al., 1971) the drag-plate stresses were reduced by a factor of 0.67 by calibration with the sonic-anemometer stresses, Wieringa concludes (p. 423) that '. . . it seems probable that the drag-plate stress measurements were generally correct'. He then multiplies the Kansas stresses by l/O.67 = 1.5 and the heat fluxes by l/O.93 = 1.07 and amends the previous similarity analyses accordingly.
We disagree with Wieringa's assertions about these Kansas flux measurements. Specifically, we argue that * The National Center for Atmospheric Research is sponsored by the National Science Foundation.