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| Titel |
A method to account for the temperature sensitivity of TCCON total column measurements |
| VerfasserIn |
Sabrina G. Niebling, Debra Wunch, Geoffrey C. Toon, Paul O. Wennberg, Dietrich G. Feist |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250100350
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| Publikation (Nr.) |
 EGU/EGU2014-16288.pdf |
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| Zusammenfassung |
| The Total Carbon Column Observing Network (TCCON) consists of ground-based Fourier
Transform Spectrometer (FTS) systems all around the world. It achieves better than 0.25%
precision and accuracy for total column measurements of CO2 [Wunch et al. (2011)]. In
recent years, the TCCON data processing and retrieval software (GGG) has been improved to
achieve better and better results (e. g. ghost correction, improved a priori profiles, more
accurate spectroscopy).
However, a small error is also introduced by the insufficent knowledge of the true
temperature profile in the atmosphere above the individual instruments. This knowledge is
crucial to retrieve highly precise gas concentrations. In the current version of the retrieval
software, we use six-hourly NCEP reanalysis data to produce one temperature profile at local
noon for each measurement day. For sites in the mid latitudes which can have a large
diurnal variation of the temperature in the lowermost kilometers of the atmosphere,
this approach can lead to small errors in the final gas concentration of the total
column.
Here, we present and describe a method to account for the temperature sensitivity of the
total column measurements. We exploit the fact that H2O is most abundant in the lowermost
kilometers of the atmosphere where the largest diurnal temperature variations occur. We
use single H2O absorption lines with different temperature sensitivities to gain
information about the temperature variations over the course of the day. This information
is used to apply a posteriori correction of the retrieved gas concentration of total
column.
In addition, we show that the a posteriori temperature correction is effective by applying it
to data from Lamont, Oklahoma, USA (36,6°N and 97,5°W). We chose this site because
regular radiosonde launches with a time resolution of six hours provide detailed information
of the real temperature in the atmosphere and allow us to test the effectiveness of our
correction.
References: Wunch, D., Toon, G. C., Blavier, J.-F. L., Washenfelder, R. A.,
Notholt, J., Connor, B. J., Griffith, D. W. T., Sherlock, V., and Wennberg, P. O.: The
Total Carbon Column Observing Network, Philosophical Transactions of the Royal
Society A: Mathematical, Physical and Engineering Sciences, 369, 2087–2112, 2011. |
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