Impact Assessment of Uncertainty of Spectroscopic Parameters on the Accuracy of Trace Gases Abundance
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Date
2007-07
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Addis Ababa University
Abstract
We have studied sensitivity of the retrieved state vector (the atmospheric parameters)
such as concentration (volume mixing ratio) profiles of targeted trace gases to
uncertainty in spectroscopic parameters. Spectral line strength and pressure broadened
half width of air are the spectroscopic parameters considered for this study.
The atmospheric trace gases, for which the sensitives studies are performed, include
source gases such H2O, N2O, CH4 and SO2, and stratospheric gases such as HNO3
and O3. The uncertainties of spectroscopic parameters considered ranges from 0.1%
to 20% for spectral line strength and 0.1% to 3% for pressure broadened half width of
air. The comparisons of difference of VMR of retrieved trace gases with and without
perturbation of the spectroscopic parameters have shown different characteristics for
different gases. The sensitivity is high at lower altitudes for source gases (H2O, N2O,
CH4) while the sensitivity for stratospheric gases (HNO3 and O3) is high at the altitude
of peak VMR. In the case of SO2, the impact is not noticeable, which is believed
to be linked with undetectable level of SO2 under normal atmospheric conditions
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Accuracy of Trace Gases Abundance