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Analyses of atmospheric CHF2Cl, heavy ozone, HDO and CH3D from ATMOS spectra

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  • Physics


NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Mixing ratio measurements of tropospheric CHF2C1 and stratospheric heavy ozone ([...] and [...]), HDO and CH3D were derived from Atmospheric Trace Molecule Spectroscopy Experiment (ATMOS) spectra. The ATMOS instrument is a 0.01 cm-1 resolution, solar-absorption Fourier-transform spectrometer with a frequency response of 600-4800 cm-1 in the mid-infrared. It has recorded ground-based spectra over Table Mountain Facility (TMF), Wrightwood CA (34.4°N, 117.7°W, 2.2 km altitude) between 1985 to 1990, and space-based measurements during the four shuttle missions Spacelab 3 (April/May 1985), ATLAS-1 (March, 1992), ATLAS-2 (April, 1993) and ATLAS-3 (November, 1994). The measured column burden of CHF2C1 over TMF showed an exponential increase rate of (6.7±0.5)% yr-1 from October, 1985 to July, 1990. The current uncertainty in historical CHF2C1 emissions was found to be too large for CHF2C1 measurements to be used to infer adequately either its lifetime or the OH field. Enrichments of heavy ozone (with respect to [...]) were measured from both space and ground-based observations. Average enrichments between 26 to 2.6 mb inclusive to 41 km) were (15±6)% for [...], (10±7)% for [...], and (13±5)% for [...] ([...] standard deviation). Enrichments increased slightly with altitude, but with no discernable latitudinal variability. From TMF, an average total column [...] enrichment of (17±4)% ([…] standard deviation) was determined, with no discernable seasonal variation. Possible biases in the spectral intensities that affect the determination of absolute enrichments are discussed, but any corrections to these intensities would not affect the observed lack of latitudinal and seasonal variability. From space-based measurements, stratospheric mixing ratios of [...] from 100 mb to 17mb ([...] to 28 km) and HDO from 100 mb to 10 mb ([...] to 32 km) were inferred. The average lifetime of [...]was found to be (1.19±0.02) times that of [...], with an average of (1.0±0.1) molecules of stratospheric HDO produced for each [...] destroyed ([...] combined precision and systematic error), indicating that the rate of stratospheric HDO production is approximately equal to the rate of [...] destruction.

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