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Aerosol-landscape-cloud interaction : Signatures of topography effect on cloud droplet formation

Romakkaniemi, S.; Maalick, Z.; Hellsten, A.; Ruuskanen, A.; Väisänen, O.; Ahmad, I.; Tonttila, J. 1; Mikkonen, S.; Komppula, M.; Kühn, T.
1 Karlsruher Institut für Technologie (KIT)


Long-term in situ measurements of aerosol–cloud interactions are usually performed in measurement stations residing on hills, mountains, or high towers. In such conditions, the surface topography of the surrounding area can affect the measured cloud droplet distributions by increasing turbulence or causing orographic flows and thus the observations might not be representative for a larger scale. The objective of this work is to analyse, how the local topography affects the observations at Puijo measurement station, which is located in the 75 m high Puijo tower, which itself stands on a 150 m high hill. The analysis of the measurement data shows that the observed cloud droplet number concentration mainly depends on the cloud condensation nuclei (CCN) concentration. However, when the wind direction aligns with the direction of the steepest slope of the hill, a clear topography effect is observed. This finding was further analysed by simulating 3-D flow fields around the station and by performing trajectory ensemble modelling of aerosol- and wind-dependent cloud droplet formation. The results showed that in typical conditions, with geostrophic winds of about 10 m s−1, the hill can cause updrafts of up to 1 m s−1 in the air parcels arriving at the station. ... mehr

Volltext §
DOI: 10.5445/IR/1000072213
DOI: 10.5194/acp-17-7955-2017
Zitationen: 4
Web of Science
Zitationen: 4
Zitationen: 5
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung – Forschungsbereich Troposphäre (IMK-TRO)
KIT-Zentrum Klima und Umwelt (ZKU)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2017
Sprache Englisch
Identifikator ISSN: 1680-7316, 1680-7324
KITopen-ID: 1000072213
HGF-Programm 12.01.01 (POF III, LK 01) Clouds in a pertubed atmosphere
Erschienen in Atmospheric chemistry and physics
Verlag European Geosciences Union (EGU)
Band 17
Heft 12
Seiten 7955-7964
Nachgewiesen in Web of Science
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