Firing of ten Aerobee rockets, each carrying 18 to 19 high‐explosive grenades at Fort Churchill, Canada, have resulted in the accurate measurement of temperatures and winds in the atmosphere up to 95 km during November 1956, July, August, and December 1957, and January 1958. One hundred and fifty measurements of temperatures and of winds were made over the period. Each measurement represents the average temperature and wind of an atmospheric layer of about 3‐km thickness. The results show clearly a seasonal variation, with average summer temperatures of 275°K at the mesopeak (about 50 km) and 170°K at the mesopause (about 80 km); corresponding average winter temperatures are 260°K and 230°K. In summer, prevailing winds above 25 km were from the east, usually less than 50 m/sec. In winter these winds were from the west, usually between 50 and 100 m/sec but frequently exceeding 100 m/sec. A breakdown in circulation up to 80 km is indicated by the wind results of two firings on January 27, 1958, where strong northerly and southerly wind components were measured. This phenomenon coincides with the occurrence of sharp temperature increases at stratospheric levels over large parts of the northern hemisphere east of Churchill. Remarkable temperature inversions between 50 and 80 km were measured in all winter firings. These inversions resulted in secondary temperature peaks above 50 km. On December 11, 1957, the temperature at 72 km was about 290°K. In summer, temperatures at 50 km and below at Churchill (59°N) were higher than at White Sands (33°N); above 65 km the Churchill temperatures were lower. This picture is reversed in winter. Only minor diurnal temperature variations were detected. No sound energy from detonations of 4‐pound high‐explosive charges above 95 km was detected on the ground with microphones of 1‐dyne cm2 sensitivity in the frequency range 8 to 25 cycles/sec.

University o• Michi•]an Ann Arbor, MichiganTen Aerobee Rockets, each instrumented with 19 high-explosive grenades, were fired to altitudes up to 100 km at Fort Churchill, Canada (59øN), as part of the United States IGY Rocket Program. The grenades exploded successively at predetermined altitude intervals of about 3 km during the ascent of the rocket. With the aid of a highly accurate electronic tracking system (I)OVAP) and microphone arrays on the ground, the time and location of each grenade burst, as well as the time and direction of the sound wave arriving at the ground, were precisely determined. From these data the average temperature and wind in the layer between two explosions could be calculated [Stroud and others, 1956]. Complete preliminary results have been obtained from all ten firings, five of which occurred in winter (November 1956, December 1957, and January 1958) and five in summer (July and August 1957). Averaged summer and winter temperature data are plotted in Figure 1. In summer, the very pronounced temperature maximum at 50 km varied from 265øK to 285øK in individual flights. Below the temperature maximum the gradient is 2.5øC per km; above, the lapse rate is -3.5øC per km. In contrast, in the winter the temperature maximum at 55 km varies from 255øK to 275øK and is far less pronounced than in summer. Below 50 km the gradient is about the same as in summer, but above the peak we have obtained a wider range of temperature in what is apparently a highly x Now with National Aeronautics and Space Administration, Washington, D.C. 9O 8O 7O ,,' 60 • 50 <• 40 ra $0 20 I0 o 17o 19o 21o 230 250 270 290 TEMPERATURE (OK) FIO. 1--Fort Churchill rocket-grenade temperature data. The curves are the rough averages of the summer and winter firings and coincident Rawin data. Some White Sands Missile Range data obtained by this experiment in the 1950-1953 are also shown. variable region of the arctic winter atmosphere. Some flights showed a series of secondary minima and maxima. If one averages the data, a lapse rate of --1 øC per km is obtained. The most outstanding results of these new 1342

The method and analysis of the rocket‐grenade experiment are briefly described. The 59 values of temperatures and of wind speeds and directions between 30 and 80 km obtained during 12 Aerobee rocket firings are summarized. The mean temperature distribution has a maximum of about 270°K at 50 km, with a lapse rate of about 2.5°/km above the peak. The winds are strong and from the west during the winter months (October through February); less strong and from the east during the summer months (April through August); and are comparatively weak and predominantly from the north during the fall (September). The maximum wind speed measured was a value of 104 m/sec at 55 km during a winter firing. The average probable error for the temperature data is ±5°C; the average errors in wind speed and direction are ±10 m/sec and ±18°, respectively.

The Tiros meteorological satellite contains detectors, storage, and telemetry for the measurement of infrared and reflected solar radiation from the earth and its atmosphere. Two separate detector designs are employed: a medium‐resolution scanning radiometer and a low‐resolution nonscanning radiometer. The spin of the satellite provides the scan line of the medium‐resolution radiometer, which is then advanced by the orbital motion of the satellite. Five channels using bolometer detectors and filters to limit the spectral response from 6 to 6.5 microns, 8 to 12 microns, 0.25 to 6 microns, 8 to 30 microns, and 0.55 to 0.75 micron are mounted in a single housing with choppers and pre‐amplifers. The spatial resolution is about 40 miles square when viewing the earth directly beneath the satellite. The parameters studied by these spectral regions are, in the same order: radiation emerging in the water vapor absorption band, day and night time cloud cover, albedo, thermal radiation, and visual maps for comparison with television pictures from the vidicon cameras also carried in the satellite. The low‐resolution nonscanning radiometer, utilizing a simple unchopped design, measures the blackbody temperature and the albedo of the earth. The field of view of the detector when viewing the earth directly beneath the satellite is a circle of 450‐mile diameter and covers part of the area of each picture frame of the wide‐field television camera. The detector consists of two thermistors, each mounted in the apex of a reflective Mylar cone which provides optical gain. One thermistor, coated black, responds to both reflected solar radiation and the thermal radiation from the earth; the second reflects solar radiation and responds only to the thermal radiation. The design, calibration, performance, and data reduction of both systems are discussed.

The zenithal distribution of particles at high altitudes observed with counter telescopes has been compared with simple calculations concerning the multiplicity and angular divergence of secondary particles. The observations are in agreement with a sharply collimated forward type of production event, and disagree with the wide angle type of production of hard secondaries. The azimuthal distributions and zenithal distributions indicate a nearly isotropic primary flux, in agreement with geomagnetic considerations at geonetic latitude 56°N. The effects of the atmosphere on directional asymmetry measurements at 13-g/cm 2 atmospheric depths are concluded to be small, especially if lead filters of a few cm thickness are used. The number of low energy particles is small at this depth.