THE ZERO-CURTAIN EFFECT - HEAT AND MASS-TRANSFER ACROSS AN ISOTHERMAL REGION IN FREEZING SOIL

The term zero curtain refers to the effect of latent heat in maintaining temperatures near 0°C over extended periods in freezing or thawing soils. Analysis of thermal data from an arctic site and a mid‐latitude location suggests that the phenomenon may be a universal characteristic of wet, medium‐textured mineral and organic soils during freezing. Nonconductive processes play an important role in formation and maintenance of the zero‐curtain effect. Water advection, condensation, and evaporation events are recognizable in mappings of thermal and ion concentration records on time‐depth meshes. The zero curtain appears to be produced and maintained by vapor transport and internal distillation mechanisms, driven by osmotic potential variations induced by freeze‐thaw events at the soil surface. The term zero curtain is applicable to locations outside permafrost regions, but units of measurements should not be assigned to it. Copyright 1990 by the American Geophysical Union.