James N. Brooks

Distribution of Nitric Acid Vapor in the Stratosphere as Determined from Infrared Atmospheric Emission Data

Abstract Infrared emission spectra were measured in the stratosphere at various altitudes and from various zenith angles by means of a balloon-borne Czerny-Turner spectrometer. The equation of radiative transfer was applied to the radiances measured at 11.2μ to yield a concentration profile of HNO3 vapor. The resulting HNO3 concentration profile was characterized by a negligible concentration below 14 km, a maximum concentration of ∼(1.5±0.5)×1010 molecules cm−3 at ∼(19±5) km, and a diminishing concentration above these altitudes.

Distribution of Water Vapor in the Stratosphere as Determined from Balloon Measurements of Atmospheric Emission Spectra in the 24–29-μm Region

The stratospheric water vapor mixing ratio altitude profile has been derived from spectral observations of the downward night emission from the pure rotation water vapor lines in the 24-29-microm region of the spectrum. The data were obtained during two balloon flights, made on 22 February 1971 and on 29 June 1971, using a balloon-borne spectral radiometer with ~2 cm(-1) resolution. The observed radiances have been fitted to line-by-line, layer-by-layer radiance calculations, from which the water vapor mixing ratio between 10 km and 30 km has been flights show a broad minimum around of 6 x 10(-7)g/g to 4 x 10(-6) g/g.

Abundance of N 2 O in the Atmosphere between 4.5 and 13.5 km

The variation with altitude of the ir solar spectrum, in the 4.5-μ region, was observed from a balloon-borne grating spectrometer. Quantitative analysis of the N2O absorption lines in this region has shown that the N2O concentration between 4.5 and 13.5 km is 0.14±04 ppm.

Atmospheric Absorptions in the Near Infrared at High Altitudes

The results of a flight with a balloon borne infrared spectrograph are presented. Solar spectra of the region from 1 to 5 μ were obtained at altitudes from 60 000 to 100 000 ft. The atmospheric absorption data obtained from these spectra are compared with theoretical predictions of slant path absorptions and with laboratory data for constant pressure path. It is found that, if the absorption is treated as a function of Pw, the laboratory data and flight data can be fitted by relations of similar form but with different constants.

Balloon-Borne Infrared Measurements

The previous speakers have discussed the general aspects of atmospheric IR measurements. In this discussion I will emphasize atmospheric IR measurements made using a balloon platform. Currently available balloons will carry 500 kg instrumentation packages to 40 km almost routinely. This weight capability is of considerable advantage for IR measurements, and the balloon is a very good vehicle for making measurements up to these altitudes.

Spectral Radiometric Measurement Of Atmospheric Constituents

Atmospheric constituent vertical profiles have been determined from the height derivatives of their measured emission spectra. Samples of these spectra and derived profiles are shown. Several spectral radiometers have been employed to obtain these data from balloon and aircraft platforms. The radiometers are scanning grating monochromators operated at liquid nitrogen and liquid helium temperatures. The optical properties of these radiometers are discussed. Also the effect of these properties on radiometric accuracy is considered. Finally, a few methods for testing the accuracy of atmospheric data are developed.

Optical Measurements from High Altitude Balloons

A description is given of a system that has been constructed to make radiometric measurements from high altitude balloons. The instrumentation consists of a 20-cm aperture, 30-cm focal length radiometer that has been equipped to scan in azimuth and elevation, a filter system so that spectral data can be obtained, an onboard digital magnetic tape recording system for recording the data generated during the flight, auxiliary electronics and power supplies for operation of the equipment, and a gondola to serve as a suitable scanning platform and to protect the equipment when it is returned to the ground by parachute at the end of the flight. The results obtained on a balloon flight made with this equipment on May 8, 1959 are also presented. For this flight the radiometer was equipped with a thermistor bolometer detector with a KRS-5 window and with filters that transmitted radiation from 1 μ to 2 μ, 2 μ to 3 μ, 3 μ to 5 μ, 5 μ to 8 μ, and 8 μ to 35 μ. These results are presented in the form of isoradiance plots.

10 to 12 μm Spectral Emissivity of a Cirrus Cloud

Abstract A balloon flight made 4 February 1970 with an infrared spectral radiometer system scanning from 10 to 13 μm ascended through an extensive cirrus cloud. This allowed measurements to be made of the spectral radiance of the cloud both underneath and in the cloud as the balloon ascended. The spectra obtained are presented and the data were used to determine the emissivity of the cloud at 11 μm. The value ∈=0.38 is in reasonable agreement with values found by Kuhn and Weickmann.