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| Titel |
Summertime impact of convective transport and lightning NOx production over North America: modeling dependence on meteorological simulations |
| VerfasserIn |
C. Zhao, Y. Wang, Y. Choi, T. Zeng |
| 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 ; 9, no. 13 ; Nr. 9, no. 13 (2009-07-03), S.4315-4327 |
| Datensatznummer |
250007487
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| Publikation (Nr.) |
 copernicus.org/acp-9-4315-2009.pdf |
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| Zusammenfassung |
| Global-scale chemical transport model simulations
indicate lightning NOx dominates upper tropospheric O3 production
above Eastern North America during summertime but vary in their estimates.
To improve our understanding, a regional-scale model (REAM) with higher
resolution is applied. To examine the uncertainties in modeling the impact
of convective transport and lightning NOx production on upper
tropospheric chemical tracer distributions, REAM simulations of chemical
tracers are driven by two meteorological models, WRF and MM5, with different
cumulus convective parameterizations. The model simulations are evaluated
using INTEX-A aircraft measurements and satellite measurements of NO2
columns and cloud top pressure, and we find that mid and upper tropospheric
trace gas concentrations are affected strongly by convection and lightning
NOx production. WRF with the KF-eta convection scheme simulates larger
convective updraft mass fluxes below 150 hPa than MM5 with the Grell scheme.
The inclusion of the entrainment and detrainment processes leads to more
outflow in the mid troposphere in WRF than MM5. The ratio of
C2H6/C3H8 is found to be a sensitive parameter to
convective outflow; the simulation by WRF-REAM is in closer agreement with
INTEX-A measurements than MM5-REAM, implying that convective mass fluxes by
WRF are more realistic. WRF also simulates lower cloud top heights (10–12 km)
than MM5 (up to 16 km), and hence smaller amounts of estimated
(intra-cloud) lightning NOx and lower emission altitudes. WRF simulated
cloud top heights are in better agreement with GOES satellite measurements
than MM5. Simulated lightning NOx production difference (due primarily
to cloud top height difference) is mostly above 12 km. At 8–12 km, the
models simulate a contribution of 60–75% of NOx and up to 20 ppbv of
O3 from lightning, although the decrease of lightning NOx effect
from the Southeast to Northeast and eastern Canada is overestimated. The
model differences and biases found in this study reflect some major
uncertainties of upper tropospheric NOx and O3 simulations driven
by those in meteorological simulations and lightning parameterizations. |
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