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| Titel |
Long-Term Trend of Carbon Tetrachloride (CCl4) from Ground-based High Resolution Infrared Solar Spectra recorded at the Jungfraujoch |
| VerfasserIn |
Curtis Rinsland, Emmanuel Mahieu, Philippe Demoulin, Linda Chiou, Rodolphe Zander, Jean-Michel Hartmann |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250032999
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| Zusammenfassung |
| The long-term trend of carbon tetrachloride (CCl4) has been retrieved from infrared high
resolution solar absorption spectra encompassing the 1999 to 2010 time period.
The measurements were recorded with a Fourier transform spectrometer at the
northern mid-latitude, high altitude Jungfraujoch station in Switzerland (46.5Ë N
latitude, 8.0Ë E longitude, 3580 m altitude). Total columns were derived from the
region of the strong CCl4 ν3 band at 794 cm-1 accounting for all interfering
molecules (e.g. H2O, O3) with significant improvement in the residuals obtained by also
taking into account the line mixing in a nearby CO2 Q branch, a procedure not
implemented in previous remote sensing CCl4 retrievals though its importance
has been noted in several papers. The time series shows a statistically-significant
long-term decrease in the CCl4 total atmospheric burden of -1.18±0.10 %/yr, at
the 95% confidence level, using 2005 as reference. Furthermore, fit to the total
column data set also reveals a seasonal cycle with a peak-to-peak amplitude of 10.2%,
with minimum and maximum values found in mid-February and early August,
respectively. This seasonal modulation can however be attributed to tropopause height
changes throughout the season. The results quantify the continued impact of the
regulations implemented by the Montreal Protocol and its strengthening amendments
and adjustments for a molecule with high global warming potential. Although a
statistically significant decrease in the total column is inferred, the CCl4 molecule
remains an important contributor to the stratospheric chlorine budget and burden. |
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