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| Titel |
Tropical troposphere to stratosphere transport of carbon monoxide and long-lived trace species in the Chemical Lagrangian Model of the Stratosphere (CLaMS) |
| VerfasserIn |
R. Pommrich, R. Müller, J.-U. Grooß, P. Konopka, F. Ploeger, B. Vogel, M. Tao, C. M. Hoppe, G. Günther, N. Spelten, L. Hoffmann, H.-C. Pumphrey, S. Viciani, F. D'Amato, C. M. Volk, P. Hoor, H. Schlager, M. Riese |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 7, no. 6 ; Nr. 7, no. 6 (2014-12-08), S.2895-2916 |
| Datensatznummer |
250115791
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| Publikation (Nr.) |
 copernicus.org/gmd-7-2895-2014.pdf |
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| Zusammenfassung |
| Variations in the mixing ratio of trace gases of tropospheric origin
entering the stratosphere in the tropics are of interest for
assessing both troposphere to stratosphere transport fluxes in the
tropics and the impact of these transport fluxes on the composition
of the tropical lower stratosphere. Anomaly patterns of carbon
monoxide (CO) and long-lived tracers in the lower tropical
stratosphere allow conclusions about the rate and the variability of
tropical upwelling to be drawn. Here, we present a simplified
chemistry scheme for the Chemical Lagrangian Model of the
Stratosphere (CLaMS) for the simulation, at comparatively low
numerical cost, of CO, ozone, and long-lived trace substances
(CH4, N2O, CCl3F (CFC-11), CCl2F2
(CFC-12), and CO2) in the lower tropical stratosphere. For
the long-lived trace substances, the boundary conditions at the
surface are prescribed based on ground-based measurements in the
lowest model level. The boundary condition for CO in the lower
troposphere (below about 4 km)
is deduced from MOPITT measurements.
Due to the lack of a specific representation of
mixing and convective uplift in the troposphere in this model
version, enhanced CO values, in particular those resulting from
convective outflow are underestimated. However, in the tropical
tropopause layer and the lower tropical stratosphere, there is
relatively good agreement of simulated CO with in situ measurements
(with the exception of the TROCCINOX campaign, where CO in the
simulation is biased low ≈10–15 ppbv). Further, the
model results (and therefore also the ERA-Interim winds, on which
the transport in the model is based) are of sufficient quality to
describe large scale anomaly patterns of CO in the lower
stratosphere. In particular, the zonally averaged tropical CO
anomaly patterns (the so called "tape recorder" patterns)
simulated by this model version of CLaMS are in good agreement with
observations, although the simulations show a too rapid upwelling compared to
observations as a consequence of the overestimated vertical
velocities in the ERA-Interim reanalysis data set. Moreover, the
simulated tropical anomaly patterns of N2O are in good
agreement with observations. In the simulations, anomaly patterns
of CH4 and CFC-11 were found to be very similar to those of
N2O; for all long-lived tracers, positive anomalies are
simulated because of the enhanced tropical upwelling in the easterly
shear phase of the quasi-biennial oscillation. |
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