Laboratory Investigation on the Immersion Freezing Behavior of Arctic Aerosols Collected in Ny-Ålesund, Svalbard

The change in cloud feedbacks affects the Arctic atmosphere, where the temperature is warming faster than anywhere else on the planet. This effect is known as the Arctic polar amplification. While sea ice-albedo feedback has been well studied, our scientific knowledge regarding the contribution of aerosol-cloud interactions on the Arctic amplification, especially atmospheric ice nucleation processes, remains scarce. Given the current concerns of the climate change, we availed ourselves to collect aerosol samples and study atmospheric ice nucleating particles (INPs) in Ny-Ålesund, Svalbard in March 2017. A total of ten aerosol samples were collected using 47 mm membrane filters at the Gruvebadet observatory (~55 m above sea level) over the period of March 2-27, 2017. The average sample volume of air collected per filter at STP (T_std = 273 K, P_tsd = 1013.5 mb) was ~22,500 L (±15% relative standard error). Further, the mean (± standard deviation) particle concentration (0.01-20 µm) while sampling was ~125 ± 77 cm^-3 with three distinct periods of different aerosol concentration levels, including low- (L), moderate- (M) and high (H) particle concentration periods. On average, the measured aerosol concentrations in these individual periods, L = 3/1 0:00 – 3/3 0:00, M = 3/4 0:00 – 3/12 9:00 and H = 3/21 19:30 – 3/30 7:30, were 47.0 cm^-3, 93.0 cm^-3 and 195.2 cm^-3, respectively. With our filter samples along complementary physico-chemical measurements, we have run the immersion freezing test by using the Cryogenic Applied Freezing Test (CRAFT) to study the freezing efficiency of Arctic aerosols above temperatures of -30 °C and its relevance to meteorological conditions. We will present the first ice nucleation dataset from the Gruvebadet observatory in Ny-Ålesund, Svalbard. Overall, our comprehensive effort of both online and offline aerosol characterizations may contribute to revealing the identity of Arctic INPs and provide the information regarding how they interact with water vapor and/or supercooled water droplets in the Arctic mixed-phase clouds. Such data will be crucial to constrain current atmospheric models and estimate their potential impact on aerosol-cloud-climate interactions in the Arctic region.

Acknowledgements:

We thank the Japanese Arctic research consortium, ArCS (Arctic Challenge for Sustainability), for the funding support. K. Cory acknowledges the NSF-EAPSI fellowship and Dr. Yutaka Tobo for financial support and research mentorship, respectively. N. Hiranuma acknowledges the Graduate Office of WTAMU and Ms. Maria Pantazi for financial/partial support.