Evolution of aerosol and CCN properties on the Antarctic Peninsula and Southern Ocean during the spring and summer seasons.

Abstract:

The Southern Ocean has been identified as one of the key regions that need aerosol measurements to improve our models of global climate change. The Portable AERosol Observing System (PAEROS) was deployed in an extended field campaign to measure CCN and aerosols in Antarctica and the Southern Ocean from October 2013 to mid-March 2014. PAEROS is a lightweight, man-portable instrument package developed at the Scripps Institution of Oceanography for the purpose of collecting autonomous measurements of aerosol and cloud condensation nuclei (CCN) properties in remote and challenging environments. The initial phase involved the PAEROS package sampling onboard the R/V Gould during the five-day transit of the Drake Passage between Punta Arenas, Chile and Palmer Station on the Antarctic Peninsula. Upon arrival at Palmer Station, PAEROS was transferred to land and installed on top of a hill about 500 m from the main buildings. For five months, aerosol and CCN number concentrations, size distributions, black carbon concentrations, solar fluxes, and meteorological parameters were continuously measured at Palmer Station. The experiment covered most of an austral spring and summer cycle, during which time the sea ice retreated and biological activity flourished along the Antarctic Peninsula. While crossing the Drake Passage, a distinct gradient in aerosol concentrations was observed with increasing distance from South America. At Palmer Station, the total aerosol concentrations showed a seasonal cycle with lowest concentration in air masses originating from the Antarctic continent and highest number concentrations coming from the ocean during the peak of biological activity. Chlorophyll concentrations are routinely measured at Palmer Station and showed peak activity in the month of January 2014. Total aerosol and CCN concentrations increased in late spring (November) as the sea ice recedes from Palmer Station, probably a result of being closer to sea spray and biological activity. Aerosol hygroscopicity decreased for ultrafine particles during the biological periods, which suggests enhanced organic contribution to the composition of smaller particles.