THE ACCURACY OF WINDS DERIVED BY THE RADAR TRACKING OF CHAFF AT HIGH ALTITUDES

The accuracy and significance of a series of wind measurements at Johnston Island are discussed. The manner in which the chaff responds to changes in the wind is deduced from the observed rates of fall. The standard error of the wind determination due to random errors of tracking is estimated statistically. It is shown that day-to-day variations of the wind at a level are detectable with this type of measurement but that day-to-day variations of the shear are masked by instrumental error. The mean shear over the 3-day period, however, is found to be real and may be due to a change in wind regime associated with the temperature minimum near 80 km.