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| Titel |
Effect of bacterial ice nuclei on the frequency and intensity of lightning activity inferred by the BRAMS model |
| VerfasserIn |
F. L. T. Gonçalves, J. A. Martins, R. I. Albrecht, C. A. Morales, M. A. Silva Dias, C. E. Morris |
| 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. 13 ; Nr. 12, no. 13 (2012-07-02), S.5677-5689 |
| Datensatznummer |
250011292
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| Publikation (Nr.) |
 copernicus.org/acp-12-5677-2012.pdf |
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| Zusammenfassung |
| Many studies from the last decades have shown that airborne microorganisms
can be intrinsically linked to atmospheric processes. Certain bacteria may
constitute the most active ice nuclei found in the atmosphere and might have
some influence on the formation of ice crystals in clouds. This study deals
with the ice nucleation activity of Pseudomonas syringae inside of thunderstorms through
numerical simulations using BRAMS (Brazilian Regional Atmospheric Model System). The numerical simulations were
developed in order to investigate the effect on the total amount of
rainwater as a function of ice nuclei (IN) P. syringae concentrations with different
scenarios (classified as S2 to S4 scenarios) corresponding to a maximum of
102 to 104 IN bacteria per liter of cloud water plus the BRAMS
default (classified as S5 scenario). Additionally, two other scenarios were
included without any IN (S1) and the sum of RAMS default and S4 scenario
(classified as S6). The chosen radiosonde data is for 3 March 2003,
typical summertime in São Paulo City which presents a strong convective
cell. The objective of the simulations was to analyze the effect of the IN
concentrations on the BRAMS modeled cloud properties and precipitation. The
simulated electrification of the cloud permitted analysis of the total
flashes estimated from precipitable and non-precipitable ice mass fluxes in
two different lightning frequencies. Among all scenarios, only S4 and S6
presented a tendency to decrease the total cloud water, and all bacteria
scenarios presented a tendency to decrease the total amount of rain
(−8%), corroborating other reports in the literature. All bacteria
scenarios also present higher precipitable ice concentrations compared to S5
scenario, the RAMS default. The main results present the total flash number
per simulation as well. From the results, the total flash numbers, from both
lightning frequencies, in S4 and S6 scenarios, are from 3.1 to 3.7 higher
than the BRAMS default. Even the lower bacterial concentrations (scenarios
S2 and S3) produced 3 time higher number of flashes, compared to S5
scenario. This result is a function of the hydrometeors in each simulation.
In conclusion, IN bacteria could affect directly the thunderstorm structure
and lightning formation with many other microphysical implications. |
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