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| Titel |
A new physically-based quantification of marine isoprene and primary organic aerosol emissions |
| VerfasserIn |
B. Gantt, N. Meskhidze, D. Kamykowski |
| 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. 14 ; Nr. 9, no. 14 (2009-07-24), S.4915-4927 |
| Datensatznummer |
250007523
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| Publikation (Nr.) |
 copernicus.org/acp-9-4915-2009.pdf |
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| Zusammenfassung |
| The global marine sources of organic carbon (OC) are estimated here using a
physically-based parameterization for the emission of marine isoprene and
primary organic matter. The marine isoprene emission model incorporates new
physical parameters such as light sensitivity of phytoplankton isoprene
production and dynamic euphotic depth to simulate hourly marine isoprene
emissions totaling 0.92 Tg C yr−1. Sensitivity studies using different
schemes for the euphotic zone depth and ocean phytoplankton speciation
produce the upper and the lower range of marine-isoprene emissions of 0.31
to 1.09 Tg C yr−1, respectively. Established relationships between sea
spray fractionation of water-insoluble organic carbon (WIOC) and
chlorophyll-a concentration are used to estimate the total primary sources of
marine sub- and super-micron OC of 2.9 and 19.4 Tg C yr−1,
respectively. The consistent spatial and temporal resolution of the two
emission types allow us, for the first time, to explore the relative
contributions of sub- and super-micron organic matter and marine
isoprene-derived secondary organic aerosol (SOA) to the total OC fraction of
marine aerosol. Using a fixed 3% mass yield for the conversion of
isoprene to SOA, our emission simulations show minor (<0.2%)
contribution of marine isoprene to the total marine source of OC on a global
scale. However, our model calculations also indicate that over the tropical
oceanic regions (30° S to 30° N), marine isoprene SOA may contribute
over 30% of the total monthly-averaged sub-micron OC fraction of marine
aerosol. The estimated contribution of marine isoprene SOA to
hourly-averaged sub-micron marine OC emission is even higher, approaching
50% over the vast regions of the oceans during the midday hours when
isoprene emissions are highest. As it is widely believed that sub-micron OC
has the potential to influence the cloud droplet activation of marine
aerosols, our findings suggest that marine isoprene SOA could play critical
role in modulating properties of shallow marine clouds and influencing the
climate. |
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