Abstract
Wind data at and above the 500-mb level taken from the El Paso, Tex., rawinsonde Station (rawin) and pressure-height data at the same levels from Albuquerque, N. Mex., Midland, Tex., Tueson, Ariz., and Chihuahua, Mexico, during the 1965–66 winter and the 1966 summer periods were used to study geostrophic wind deviation. Geostrophic winds were computed directly from the pressure-height data by a finite-difference method and compared to the actual wind as measured at El Paso. The variations of the “apparent” geostrophic wind deviation with wind speed and pressure-height were examined. Errors involved were analyzed and the “true” geostrophic wind deviation and the total wind accelerations were estimated. Results of the study reveal: (1) that despite the improvement in the accuracies of the radiosonde pressure-height and rawin data, the errors in the data still account for a large portion of the apparent geostrophic wind deviation at higher levels (at and above the 150-mb level); (2) that to use the geostrophic wind approximation in cases with wind speed less than 20 m/s would probably result in vector wind errors of the order of 40 percent or more; and (3) that the mean true geostrophic wind deviation increases when the mean actual wind speed increases, and the estimated mean total wind accelerations range from 1 × 10−4 to 5 × 10−4 m·s−2 at and above the 500-mb level.
