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Seasonal cycle and secular trend of the total and tropospheric column abundance of ethane above the Jungfraujoch

Journal Article · · Journal of Geophysical Research; (United States)
DOI:https://doi.org/10.1029/90JD02229· OSTI ID:5331333
;  [1]; ;  [2];  [3]
  1. Inst. fuer Atmosphaerische Chemie, Juelich (West Germany)
  2. Univ. of Liege (Belgium)
  3. NASA Langley Research Center, Hampton, VA (USA)
Total column abundances of ethane (C{sub 2}H{sub 6}) above the Jungfraujoch Station, Switzerland, 3.58-km altitude, have been deduced from infrared solar spectra recorded in 1951 and from 1984 to 1988. The results were derived from the spectroscopic analysis of the v{sub 7} band P{sub Q3}, and R{sub Q0} subbranches of C{sub 2}H{sub 6} near 2976.8, 2983.4, and 2986.7 cm{sup {minus}1} , respectively. The 1984-1988 results obtained from more than 300 observations at 0.005 cm{sup {minus}1} resolution show a definite seasonal variation in the total vertical column abundance of that gas, with a maximum of (1.43 {plus minus} 0.03) {times} 10{sup 16} molecules/cm{sup 2} during March and April and a minimum in the fall. The corresponding C{sub 2}H{sub 6} mixing ratio in the free troposphere was derived to 1.53 {plus minus} 0.14 ppb in early April; the ratio of maximum to minimun C{sub 2}H{sub 6} concentration in the troposphere was found to be 1.88 {plus minus} 0.12. From the analysis of the same spectral features observed in March and April 1951, the authors have deduced a total vertical column abundance of (1.09 {plus minus} 0.10) {times} 10{sup 16} molecules/cm{sup 2}. Assuming an exponential increase with time and correcting for a small decrease in the stratospheric amount of C{sub 2}H{sub 6} due to the man-induced increase in stratospheric chlorine, they obtain a secular trend in the tropospheric burden above the Jungfraujoch equal to (0.85 {plus minus} 0.3)% yr{sup {minus}1}. It is argued that this trend is valid for the entire northern hemisphere.
OSTI ID:
5331333
Journal Information:
Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:D3; ISSN JGREA; ISSN 0148-0227
Country of Publication:
United States
Language:
English