Distribution of ozone in the stratosphere measurements of 1939 and 1940

Continuing the measurements of ultraviolet solar radiation intensities in the stratosphere made in 1937 and 1938 (RPI207), in this paper a description is given of similar measurements made with improved apparatus in the summer of 1939 and 1940.The apparatus that was transported aloft by means of unmanned balloons consisted of the following elements: (1) a photoelectric cell and filter radiometer, connected with a balanced amplifier, relaxation oscillator, and radio transmitter for measuring the ultraviolet intensities; (2) a radio-operated barometer, giving the heights attained by the apparatus; and (3) an electrolytic resistor for measuring the ambient temperature of the ultraviolet intensity meter.The audio-frequency modulated radio wave, giving (1) the intensity of the incident ultraviolet solar radiation, (2) the elevation of the apparatus, and (3) the temperature of the ultraviolet meter, was received and graphically recorded at a fixed ground station (RP1075).In three successful flights made in June 1939, and in two similar fli ghts made in 1940, the ultraviolet radiometer attained heights r anging from about 78,000 to about 88,000 ft (23 to 27 km).From the observed change in filter transmissions of ultraviolet sola.rradiation with elevation, it is deduced that the apparatus passed through 65 to 70 percent of the ozone (and other ultraviolet-absorbing constituents, if any, in the upper atmosphere), the most of which is localized in a layer extending from 15 to 27 km, with a wide maximum of concentration at a height of about 24 to 25 km, above the earth's surface.At the highest elevation attained by the instruments, the intensity of the ultraviolet solar radiation of wavelengths shorter than 3132 A was 10 to 12 times that observed at sea level.