 |
| Titel |
Modeling the effect of plume-rise on the transport of carbon monoxide over Africa with NCAR CAM |
| VerfasserIn |
H. Guan, R. B. Chatfield, S. R. Freitas, R. W. Bergstrom, K. M. Longo |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 8, no. 22 ; Nr. 8, no. 22 (2008-11-27), S.6801-6812 |
| Datensatznummer |
250006466
|
| Publikation (Nr.) |
 copernicus.org/acp-8-6801-2008.pdf |
|
|
|
|
|
| Zusammenfassung |
| We investigated the effects of fire-induced plume-rise on the simulation of
carbon monoxide (CO) over Africa and its export during SAFARI 2000 using the
NCAR Community Atmosphere Model (CAM) with a CO tracer and a plume-rise
parameterization scheme. The plume-rise parameterization scheme simulates
the consequences of strong buoyancy of hot gases emitted from biomass
burning, including both dry and cloud-associated (pyro-cumulus) lofting. The
current implementation of the plume-rise parameterization scheme into the
global model provides an opportunity to examine the effect of plume-rise on
long-range transport. The CAM simulation with the plume-rise
parameterization scheme seems to show a substantial improvement of the
agreements between the modeled and aircraft-measured vertical distribution
of CO over Southern Africa biomass-burning area. The plume-rise mechanism
plays a crucial role in lofting biomass-burning pollutants to the middle
troposphere. In the presence of deep convection we found that the plume-rise
mechanism results in a decrease of CO concentration in the upper
troposphere. The plume-rise depletes the boundary layer, and thus leaves
lower concentrations of CO to be lofted by the deep convection process. The
effect of the plume-rise on free troposphere CO concentration is more
important for the source area (short-distance transport) than for remote
areas (long-distance transport). A budget analysis of CO burden over
Southern Africa reveals the plume-rise process to have a similar impact as
the chemical production of CO by OH and CH4. In addition, the
plume-rise process has an minor impact on the regional export. These results
further confirm and extend previous findings in a regional model study.
Effective lofting of large concentration of CO by the plume-rise mechanism
also has implications for local air quality forecasting in areas affected by
other fire-related pollutants. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|