Ice nucleating particles (INPs) are proportionally rare aerosols that can change the radiative impact of clouds by nucleating atmospheric ice crystals at warmer temperatures and lower supersaturations than pure water. The properties that distinguish an effective INP are not well understood, but differences in INP populations exist when comparing populations measured under similar conditions but different latitudes. There has been recent interest in Arctic INPs and their response to Arctic amplification, but few studies directly compare Arctic and Temperate INPs. Here, we report offline measurements of INPs collected during 2019 and 2020 from Ny-Ålesund at 79°N and in 2020 from Graciosa Island at 39°N. These two sites provide contrasting examples of remote island sites with little local anthropogenic impact but varying levels of marine biogenic aerosols. Although both sites show comparable INP concentrations at warmer temperatures between -7 °C and -20 °C, the filters from Graciosa Island show concentrations up to an order of magnitude higher between -20 °C and -25 °C. Similarities in concentrations from the two sites may suggest a similar biogenic marine source for INPs at higher temperatures at both sites, while samples from Graciosa Island contain more lower-temperature INPs due to higher levels of Temperate terrestrial influence. HYSPLIT back-trajectory analysis indicates that both sites have strong Arctic influences, with the strongest Arctic influence seen in autumn and winter Ny-Ålesund samples. Samples from both sites show varying levels of heat sensitivity, with some samples showing reduced INP concentrations when heated, especially at high temperatures, denoting the presence of proteinaceous INPs. By comparing INPs measured at two different island locations at drastically different latitudes, we can begin to understand similarities and differences between Arctic and Temperate marine aerosol populations.
Ice Nucleating Particle Concentrations from an Arctic and a Temperate Site with Marine-Dominant Aerosol Sources
Mazzola Mauro;Traversi Rita;
2021
Abstract
Ice nucleating particles (INPs) are proportionally rare aerosols that can change the radiative impact of clouds by nucleating atmospheric ice crystals at warmer temperatures and lower supersaturations than pure water. The properties that distinguish an effective INP are not well understood, but differences in INP populations exist when comparing populations measured under similar conditions but different latitudes. There has been recent interest in Arctic INPs and their response to Arctic amplification, but few studies directly compare Arctic and Temperate INPs. Here, we report offline measurements of INPs collected during 2019 and 2020 from Ny-Ålesund at 79°N and in 2020 from Graciosa Island at 39°N. These two sites provide contrasting examples of remote island sites with little local anthropogenic impact but varying levels of marine biogenic aerosols. Although both sites show comparable INP concentrations at warmer temperatures between -7 °C and -20 °C, the filters from Graciosa Island show concentrations up to an order of magnitude higher between -20 °C and -25 °C. Similarities in concentrations from the two sites may suggest a similar biogenic marine source for INPs at higher temperatures at both sites, while samples from Graciosa Island contain more lower-temperature INPs due to higher levels of Temperate terrestrial influence. HYSPLIT back-trajectory analysis indicates that both sites have strong Arctic influences, with the strongest Arctic influence seen in autumn and winter Ny-Ålesund samples. Samples from both sites show varying levels of heat sensitivity, with some samples showing reduced INP concentrations when heated, especially at high temperatures, denoting the presence of proteinaceous INPs. By comparing INPs measured at two different island locations at drastically different latitudes, we can begin to understand similarities and differences between Arctic and Temperate marine aerosol populations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
