Size-dependent particle activation properties in fog during the ParisFog 2012/13 field campaign

dc.contributor.authorHammer, Emanuel
dc.contributor.authorGysel, Martin
dc.contributor.authorRoberts, Greg
dc.contributor.authorElias, Thierry
dc.contributor.authorHofer, Julian
dc.contributor.authorHoyle, Christopher R.
dc.contributor.authorBukowiecki, Nicolas
dc.contributor.authorDupont, Jean-Charles
dc.contributor.authorBurnet, Frederic
dc.contributor.authorBaltensperger, Urs
dc.contributor.authorWeingartner, Ernest
dc.date.accessioned2024-02-09T08:25:00Z
dc.date.available2024-02-09T08:25:00Z
dc.date.issued2014
dc.description.abstractFog-induced visibility reduction is responsible for a variety of hazards in the transport sector. Therefore there is a large demand for an improved understanding of fog formation and thus improved forecasts. Improved fog forecasts require a better understanding of the numerous complex mechanisms during the fog life cycle. During winter 2012/13 a field campaign called ParisFog aiming at fog research took place at SIRTA (Instrumented Site for Atmospheric Remote Sensing Research). SIRTA is located about 20 km southwest of the Paris city center, France, in a semi-urban environment. In situ activation properties of the prevailing fog were investigated by measuring (1) total and interstitial (non-activated) dry particle number size distributions behind two different inlet systems; (2) interstitial hydrated aerosol and fog droplet size distributions at ambient conditions; and (3) cloud condensation nuclei (CCN) number concentration at different supersaturations (SS) with a CCN counter. The aerosol particles were characterized regarding their hygroscopic properties, fog droplet activation behavior and contribution to light scattering for 17 developed fog events. Low particle hygroscopicity with an overall median of the hygroscopicity parameter, κ, of 0.14 was found, likely caused by substantial influence from local traffic and wood burning emissions. Measurements of the aerosol size distribution at ambient RH revealed that the critical wet diameter, above which the hydrated aerosols activate to fog droplets, is rather large (with a median value of 2.6μm) and is highly variable (ranging from 1 to 5μm) between the different fog events. Thus, the number of activated fog droplets was very small and the non-activated hydrated particles were found to contribute significantly to the observed light scattering and thus to the reduction in visibility. Combining all experimental data, the effective peak supersaturation, SSpeak, a measure of the peak supersaturation during the fog formation, was determined. The median SSpeak value was estimated to be in the range from 0.031 to 0.046% (upper and lower limit estimations), which is in good agreement with previous experimental and modeling studies of fog.
dc.identifier.doi10.5194/acp-14-10517-2014
dc.identifier.issn1680-7324
dc.identifier.issn1680-7316
dc.identifier.urihttps://irf.fhnw.ch/handle/11654/44323
dc.identifier.urihttps://doi.org/10.26041/fhnw-8130
dc.issue19
dc.language.isoen
dc.publisherCopernicus
dc.relation.ispartofAtmospheric Chemistry and Physics
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.spatialGöttingen
dc.subject.ddc550 - Geowissenschaften
dc.titleSize-dependent particle activation properties in fog during the ParisFog 2012/13 field campaign
dc.type01A - Beitrag in wissenschaftlicher Zeitschrift
dc.volume14
dspace.entity.typePublication
fhnw.InventedHereNo
fhnw.ReviewTypeAnonymous ex ante peer review of a complete publication
fhnw.affiliation.hochschuleHochschule für Technikde_CH
fhnw.affiliation.institutlnstitut für Sensorik und Elektronikde_CH
fhnw.openAccessCategoryGold
fhnw.pagination10517–10533
fhnw.publicationStatePublished
relation.isAuthorOfPublication54997bb8-cf4a-4120-b0c7-f8e731e8eea1
relation.isAuthorOfPublication05dd9a19-7a24-4325-805a-2d121483b168
relation.isAuthorOfPublication.latestForDiscovery54997bb8-cf4a-4120-b0c7-f8e731e8eea1
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