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| Titel |
Thunderstorms and upper troposphere chemistry during the early stages of the 2006 North American Monsoon |
| VerfasserIn |
M. C. Barth, J. Lee, A. Hodzic, G. Pfister, W. C. Skamarock, J. Worden, J. Wong, D. Noone |
| 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 ; 12, no. 22 ; Nr. 12, no. 22 (2012-11-21), S.11003-11026 |
| Datensatznummer |
250011612
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| Publikation (Nr.) |
 copernicus.org/acp-12-11003-2012.pdf |
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| Zusammenfassung |
| To study the meteorology and chemistry that is associated with the early
stages of the North American Monsoon, the Weather Research and Forecasting
model coupled with Chemistry (WRF-Chem) is applied for the first time at
high resolution (4 km grid spacing, allowing for explicit representation of
convection) over a large region (continental US and northern Mexico) for a
multi-week (15 July to 7 August 2006) integration. Evaluation of model
results shows that WRF-Chem reasonably represents the large-scale
meteorology and strong convective storms, but tends to overestimate weak
convection. In the upper troposphere, the WRF-Chem model predicts ozone
(O3) and carbon monoxide (CO) to within 10–20% of aircraft and sonde
measurements. Comparison of UT O3 and CO frequency distributions
between WRF-Chem and satellite data indicates that WRF-Chem is lofting CO
too frequently from the boundary layer (BL). This excessive lofting should
also cause biases in the WRF-Chem ozone frequency distribution; however it
agrees well with satellite data suggesting that either the chemical
production of O3 in the model is overpredicted or there is too much
stratosphere to troposphere transport in the model. Analysis of different
geographic regions (West Coast, Rocky Mountains, Central Plains, Midwest,
and Gulf Coast) reveals that much of the convective transport occurs in the
Rocky Mountains, while much of the UT ozone chemical production occurs over
the Gulf Coast and Midwest regions where both CO and volatile organic
compounds (VOCs) are abundant in the upper troposphere and promote the
production of peroxy radicals. In all regions most of the ozone chemical
production occurs within 24 h of the air being lofted from the boundary
layer. In addition, analysis of the anticyclone and adjacent air indicates
that ozone mixing ratios within the anticyclone region associated with the
North American Monsoon and just outside the anticyclone are similar.
Increases of O3 within the anticyclone are strongly coincident with
entrainment of stratospheric air into the anticyclone, but also are from in
situ O3 chemical production. In situ O3 production is up to 17%
greater within the anticyclone than just outside the anticyclone when the
anticyclone is over the southern US indicating that the enhancement of
O3 is most pronounced over regions with abundant VOCs. |
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