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| Titel |
Modelling global emissions of bacteria and fungal spores acting as ice nuclei |
| VerfasserIn |
Ana Sesartic, Ulrike Lohmann, Trude Storelvmo, Tanja Dallafior |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250047191
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| Zusammenfassung |
| Primary biological aerosols, like bacteria and fungal spores, have been shown in laboratory
studies to be efficient ice nuclei (IN) and an important component of the biological aerosol
population in the atmosphere (Diehl et al., 2006; Kieft, 1988; Jaenicke et al., 2007). It is
necessary to know their global emissions in order to investigate their potential impact on
clouds and precipitation.
Bacteria in general and those with ice nucleating abilities in particular are commonly
found on plant leaves (Lindemann et al., 1982), which aids in determining global bacteria
concentrations depending on different plant functional types. Plant functional types and their
seasonally changing leaf area index from the JSBACH dynamic vegetation model (Raddatz et
al., 2007) were combined with observed near surface bacteria concentrations (Burrows
et al., 2009a) to calculate bacteria emissions within the ECHAM5-HAM general
circulation model (GCM) (Lohmann et al., 2007) for an online calculation of bacteria
emissions.
A review of available fungal spore concentration data has been undertaken by
Dallafior and Sesartic (2010). Those data from literature have been assigned to an
ecosystem and converted to surface fluxes. The fluxes have been calculated offline
based on ecosystem areas from JSBACH and fungal spore properties (mass and
density).
The average global fungal spore number concentrations (104 m-3) were found to be two
orders of magnitudes lower than the modelled average number concentrations of bacteria
(106 m-3) and mineral dust (108 m-3).
The inclusion of bacteria acting as IN in ECHAM5-HAM leads to only minor changes in
cloud formation and precipitation on a global level, however, changes in the liquid water path
and ice water path can be observed, specifically in the boreal regions where tundra and forests
act as sources of bacteria. Following Santl Temkiv et al. (2009) we assumed 10% of available
bacteria to act as IN.
The addition of fungal spores acting as IN in ECHAM5-HAM has an even lesser impact.
A slight increase in ice crystal number concentration over vegetated areas can be observed for
the assumption that all fungal spores act as IN. However, due to their low number
concentration fungal spores seem to have only a very minor impact on clouds and
precipitation on the global scale.
REFERENCES
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and synthesis of literature data for different ecosystems, Atmos. Chem. Phys., 9,
9263–9280.
Dallafior, T. and Sesartic A. 2010: Global Fungal Spore Emissions. Review and Synthesis
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