CASE STUDIES CONCERNING THE AIR MASS INFLUENCE ON THE NUMBER CONCENTRATION OF CLOUD CONDENSATION NUCLEI IN THE SOUTHERN OCEAN REGION DURING ACE.

From December 2016 to March 2017 the R/V “Troyshnikov” went round the Antarctic continent on the Antarctic Circumnavigation Expedition. Among a wide variety of experiments onboard aiming at the biology, oceanography and others, also atmospheric parameters where sampled, e.g., within the “Study of Preindustrial-like-Aerosol Climate Effects” (SPACE) project. As partner in this project, TROPOS focused on aerosol particles involved in aerosol cloud interactions, specifically those that are able to act as cloud condensation nuclei (CCN), as well as particles able to nucleate ice (INP). Along the 3-month lasting cruise, we observed several periods of special interest, such as several days with high number concentrations of small particles, a cold air outbreak, and air masses originating from a volcano plume. The mean CCN number concentration at 0.2 %, averaged over the whole cruise, was 120 #/ cm3. Extreme values were found close to the Antarctic continent. At Mertz Glacier we observed very low CCN concentrations (around 15 #/cm3 , January 30, 2017), but also the highest pristine concentrations (up to 300 #/cm3 , February 6, 2017) were measured close to this region. In this contribution, we will discuss possible factors (e.g., air mass origin) influencing CCN concentration and hygroscopicity. Acknowledgement: We thank the DFG for the funding within the SPP 1158. [ABSTRACT FROM AUTHOR]