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  • Author or Editor: J. M. Rosen x
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J. M. Rosen and D. J. Hofmann

Abstract

A condensation nuclei (CN) counter has been developed for balloonborne use at ambient pressures in the troposphere and stratosphere. The instrument employs a thermal gradient diffusion cloud chamber to produce particle growth and a photoelectric particle counter for detection. After extensive laboratory tests, the instrument was successfully flown on several balloon soundings over Laramie. The results show a roughly constant mixing ratio in the stratosphere with a CN concentration of about 20 cm−3 at 15 km. The vertical profile of CN in the troposphere displayed concentration fluctuations ranging between 200 and 2000 cm−3 with a definite maximum in the mixing ratio just below the tropopause.

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D. J. Hofmann, J. M. Rosen, and T. J. Pepin

Abstract

Seasonal tropopause height variations are utilized in studying the global stratospheric aerosol burden and possible ozone asymmetries and long-term variations. It is concluded that an intimate relationship between tropopause height and total stratospheric aerosol exists and that seasonal fluctuations in tropopause height may be responsible for at least a portion of the north-south hemisphere total ozone asymmetry and the recent long-term increase trend in total ozone.

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J. M. Rosen, D. J. Hofmann, and K. H. Kaselau

Abstract

Condensation nuclei measurements using a low supersaturation (∼10%) thermal gradient diffusion cloud chamber (TGDCC) and a high supersaturation (∼200%) expansion type instrument were compared on a series of three balloon flights over Laramie, Wyoming. In general the two instruments produced similar vertical profiles but some discrepancies remain unexplained. Agreement between the two would indicate that the low supersaturations used in the TGDCC were still large enough to cause the instrument to count essentially all of the particles present. The TGDCC condensation nuclei (CN) counter was flown at several sites in both the Northern and Southern Hemispheres. The results indicate the existance of a relative maximum in the CN mixing ratio associated with the upper equatorial troposphere and what appears to be a worldwide constant mixing ratio of CN above 20–25 km.

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Richard D. Cadle, Gerhard Langer, J. B. Haberl, A. Hogan, James M. Rosen, William A. Sedlacek, and J. Wegrzyn

Abstract

Laboratory comparisons have been made of aerosol concentrations indicated by four different types of condensation nucleus counters. Three of these counters, the Langer, Rosen, and General Electric SANDS instruments have been used to measure Aitken nuclei concentrations in the upper troposphere and the stratosphere, and the fourth, a Pollak counter, had been carefully calibrated to serve as a standard. Except for the smallest particles employed, quite good agreement was experienced among the Rosen, SANDS and Pollak counters, and the tests served to calibrate the Langer instrument.

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