The Efficiency of Ice Nucleating Particle Release through Sea Spray Aerosols and Various Bubble Sizes

Ice nucleating particles (INPs) are released from the ocean through sea spray aerosols (SSA). However, we know very little about the sizes or composition of these INPs, or what types of bubbles release them most efficiently. Here, bubbles producing predominantly film drops or jet drops were generated to determine how many and what sizes of aerosols they produced, as well as how this controlled the size and number of INPs emitted. To do this, frits of three sizes (145-174 µm, 25-50 µm, and 0.9 -1.4 µm) were used to produce bubbles that would generate mainly film drops, jet drops, or both. These frits were placed in a tank of artificial seawater containing birch pollen INPs of various size classes. SSA was characterized using a Scanning Mobility Particle Sizer (SMPS), Aerodynamic Particle Sizer (APS), and a Condensation Particle Counter (CPC). SSA generated were collected using an in-line filter unit, and the number of INPs collected on the filter were measured using an immersion freezing ice spectrometer. This allowed us to determine that 100 – 400 nm pollen particles are released readily through all bubble sizes, but at a slightly higher rate through film drop bubbles than through jet drop bubbles.