Research Data supporting "Background free-tropospheric ice nucleating particle concentrations at mixed-phase cloud conditions"

During the different years and seasons, we We find that INP concentrations in the background FT are on average capped at 10 stdL-1 (liter of air at standard conditions (T = 273 K and p = 1013 hPa)) with an inter-quartile range of 0.4 – 9.6 stdL-1, as compared to measurements during times when other air mass origins (e.g. Sahara or marine boundary layer) prevailed. Elevated concentrations were measured in the field campaigns of 2016, which might be due to enhanced influence from Saharan dust and marine boundary layer air arriving at the JFJ.

The upper limit of INP concentrations in the background FT is supported by measurements performed at similar conditions, but at different locations in the FT, such as ground- and airborne measurements over the central and Western United States and the Canary Islands, where we find the majority of INP concentrations to be below 13 stdL-1 most of the time.