No abstract

An average of three measurements per month of upper atmosphere winds and temperatures was made during the period July 21, 1950 through May 31, 1951 by means of acoustical propagation studies. Field operations were centered in Wray, Colorado (40 ø N. lat, 102 ø W. long) and extended radially 200 km. A variation in azimuth and distance from sound source to recorder positions permitted the separation of wind and temperature components of the observed upper atmosphere sonic velocity gradients. It was found that upper winds were generally westerly and of large magnitude during the winter (autumnal to vernal equinox) and easterly and of small magnitude during the summer, with wide fluctuations during the equinoctial periods. Short-term fluctuations in the wind vector were observed to be of the same order of magnitude as the vector itself. The short-term fluctuation is now well established. A doubly-periodic annual variation in temperature was observed above 25-km altitude, with mean value in agreement with accepted NACA values. 731 several investigators soon began employing the phenomenon of anomalous sound propagation as a means of determining temperature of the upper atmosphere; Whipple 5 and Gutenberg 6 were among the first to do quantitative work with controlled sound sources. Gutenberg 7 was the first investigator to develop a systematic means for determining a ray-path of the abnormal wave which satisfies the travel-time, distance, and velocity requirements above the limit of meteorological measurement. His method is a refinement of relations developed by Wiechert 8.9 and Herglotz. 1ø W61ken 1• in 1934 published results obtained from controlled studies in the polar region, wherein abnormal waves were received during the polar night. Of particular recent interest are the research of Cox in Idaho •' and his reduction of data obtained in the Helgoland explosions. la To date, Crary TM has developed what is probably the most complete and efficient method for determining upperatmosphere temperatures and winds by atmospheric sounding methods. He has performed controlled studies in Alaska, Hawaii, Bermuda, and the United States in the last decade. It is his method of calculation which 5 F.