Near-surface water vapor over polar sea ice is always near ice saturation

The solution to that model shows that because the polar marine boundary layer is generally thin, its timescale for reaching moisture equilibrium is much shorter than the timescale of the synoptic processes that tend to disrupt equilibrium, and because they have relatively warm surfaces, open leads and polynyas supply water vapor more rapidly than the surrounding sea ice surface can remove it, despite an open water fractional area that may be only 5%.

In concert, the two processes commonly lead to water vapor densities in the boundary layer over sea ice that are near the value for ice saturation.