Polynya

Persistent area of open water surrounded by sea ice, formed by either offshore winds and currents that advect ice away (a latent-heat polynya) or by upwelling of warmer subsurface water (a sensible-heat polynya). The WMO Sea-Ice Nomenclature distinguishes polynyas from leads by their persistence and rounded shape rather than the linear, transient form of leads. Antarctic and Arctic polynyas are biologically productive and are recurring features used by indigenous communities and by ice-class commercial vessels for staging or for loitering between assignments.