The Arctic climate changes at a faster rate than the rest of the globe. Boundary-layer clouds may play an important role to this change. At temperatures below 0°C, mixed-phase clouds exist and their phase and longevity is influenced by the abundance of ice crystals, which in turn is a function of aerosols serving as ice nucleating particles (INPs). Previous in-situ studies suggested a local source of INPs due to biological activity over open ocean. Here we investigate ice crystal concentrations in clouds below 2km at a large scale, by exploiting a newly-developed dataset - DARDAR-Nice - retrieved from active satellite remote sensing. The dataset spans from 2006-2016. Contrary to previous expectation, we find that at a given latitude and temperature, there are more ice crystals over sea ice than over open ocean. This enhancement is particularly found in clouds south of 70°N, but also at temperatures between 0 and -10°C.