J. J. Kosters

Measurements of stratospheric halocarbon distributions using infrared techniques

Absorption bands of CF2Cl2, CFCl3 and CCl4 have been observed in infrared sunset solar spectra in the 800-1000 cm−1 region from 30 km altitude during a balloon flight made in September 1975. The infrared absorption bands were used to derive the distribution of these constituents in the upper troposphere and lower stratosphere. The results are compared with 1968 data and with current results of other authors.

High resolution solar spectrometer system for measuring atmospheric constituents

A mid IR Michelson interferometer capable of obtaining 0.002-cm(-1) resolution solar spectra has been developed for balloon use. The interferometer is based on the Bomem self-aligning instrument, and is equipped with a solar tracking system, telemetry, and recording systems, as well as temperature control and gondola orientation. The interferometer has made two successful flights in the 7-14 microm (700-1300-cm(-1)) interval up to 40 km. The basic systems are described and sample spectra are presented.

Stratospheric HNO3 measurements from 0.002-cm−1 resolution solar occultation spectra and improved spectroscopic line parameters in the 5.8-μm region

Measurements of stratospheric HNO3 are presented based on new very high resolution (0.002-cm−1 full width at half maximum (FWHM)) solar occultation spectra recorded at 32°N latitude with a balloon-borne interferometer in the region of the HNO3 v2 band at 5.8 μm and improved spectroscopic line parameters generated for this HNO3 band and the interfering bands of O3 and H2O. The line parameters for HNO3, computed from the spectroscopic constants reported by Maki, are a significant improvement in that the calculated positions are more accurate than previous data and the line list now includes higher J and Ka transitions needed to account for weaker HNO3 absorption features observable in the stratospheric spectra. Verifications of the new line parameters based on the stratospheric spectra and a 0.002-cm−1 resolution HNO3 laboratory spectrum are presented along with comparisons generated with the parameters from the 1986 HITRAN compilation. Significant improvements are apparent for all the updated bands. Finally, the stratospheric HNO3 profile retrieved from the stratospheric solar spectra using a nonlinear least squares fitting algorithm and the new line parameters is reported and compared with previously reported measurements.

Balloon-borne remote sensing of stratospheric constituents

Remote-sensing techniques are generally considered as a means of obtaining data concerning the concentration species at altitudes not accessible to the observing platform; however, in the case of remote-sensing measurements of species in the lower stratosphere a considerable advantage in profile resolution can be obtained by making the measurements from balloons. Data concerning species of interest in the photochemistry of the ozone layer were obtained by balloon flights employing remote-sensing instruments making measurements in the wavelength region from the ultraviolet to millimeter wavelengths. The majority of the data were obtained using instruments to obtain data in the midinfrared wavelengths. Two techniques are generally used: solar absorption or atmospheric emission. Descriptions of the instrumentation used by our group at the University of Denver to obtain data using both techniques are given. The techniques employed in the analysis of the data obtained with these instruments are discussed, and recent results are presented. The potential of both techniques for obtaining data of interest in the photochemistry of the ozone layer is also discussed.

Atmospheric Emission Spectra Obtained From The Equator To The South Pole

A liquid helium cooled grating spectrometer system designed and constructed for field operations was used to obtain atmospheric emission spectra from California to the South Pole. Details of the design of the instrument are discussed and samples of the spectra obtained are presented.

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.

Balloon-Borne Measurements Of Infrared (IR) Backgrounds

High altitude infrared background data in the middle infrared were obtained during a series of balloon flights made several years ago. One aspect of these measurements that was difficult to explain physically was the large short-term fluctuations in the background radiation observed occasionally in Alaska. During a series of balloon flights made in 1978, data were obtained which appears to explain the observed fluctuations.

Problems In Solar Irradiance Measurements

A number of areas of current research interest require measurements of solar irradiance made with greater absolute accuracy than is currently being achieved at various monitoring sites. By using currently available instrumentation and careful measuring techniques it is shown that it is possible to measure the solar irradiance with considerable precision on a routine basis. The major problem that re-mains is making the measurements absolute; and an investigation of the standards used in pyrheliometry is required before a significant increase in absolute accuracy can be obtained.