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| Titel |
The role of horizontal model resolution in assessing the transport of CO in a middle latitude cyclone using WRF-Chem |
| VerfasserIn |
C. A. Klich, H. E. Fuelberg |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 2 ; Nr. 14, no. 2 (2014-01-21), S.609-627 |
| Datensatznummer |
250118295
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| Publikation (Nr.) |
 copernicus.org/acp-14-609-2014.pdf |
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| Zusammenfassung |
| We use the Weather Research and Forecasting with Chemistry (WRF-Chem) online
chemical transport model to simulate a middle latitude cyclone in East Asia
at three different horizontal resolutions (45, 15, and 5 km grid spacing).
The cyclone contains a typical warm conveyor belt (WCB) with an embedded
squall line that passes through an area having large surface concentrations
(> 400 ppbv) of carbon monoxide (CO). Model output from WRF-Chem
is used to compare differences between the large-scale CO vertical transport
by the WCB (the 45 km simulation) with the smaller-scale transport due to
its convection (the 5 km simulation). Forward trajectories are calculated
from WRF-Chem output using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. At 45 km grid spacing, the WCB exhibits
gradual ascent, lofting surface CO to 6–7 km. Upon reaching the warm
front, the WCB and associated CO ascend more rapidly and later turn eastward
over the Pacific Ocean. Convective transport at 5 km resolution with
explicitly resolved convection occurs much more rapidly, with surface CO
lofted to altitudes greater than 10 km in 1 h or less. We also compute CO
vertical mass fluxes over specified areas and times to compare differences
in transport due to the different grid spacings. Upward CO flux exceeds
110 000 t h−1 in the domain with explicit convection when the squall
line is at peak intensity, while fluxes from the two coarser resolutions are
an order of magnitude smaller. Specific areas of interest within the 5 km
domain are defined to compare the magnitude of convective transport to that
within the entire 5 km region. Although convection encompasses only a small
portion of the 5 km domain, it is responsible for ~40% of
the upward CO transport. We also examine the vertical transport due to a
short wave trough and its associated area of convection, not related to the
cyclone, that lofts CO to the upper troposphere. Results indicate that
fine-scale resolution with explicitly resolved convection is important when
assessing the vertical transport of surface emissions in areas of deep
convection. |
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