Review of heat and water movement in field soils

Coupled heat and water transport in soils has enjoyed extensive focus in soil physics and hydrology and yet, until recently, there has never been a satisfactory comparison of water vapor fluxes measured in the field with theory. At least two factors have led to this, first, most of the experimental work has been laboratory oriented with steady state boundary conditions imposed and second, there have been relatively few field experiments to test the existing theory. In this paper we review a new theoretical development which explains field observations of water vapor movement. The diurnal warming at the land surface leads to an expansion and contraction of the soil air as it warms and cools resulting in a convective (or "advective") transport of water vapor. This mechanism has important consequences for the transport of any vapor in the soil air near the land-atmosphere interface. (C) 1998 Published by Elsevier Science B.V. All rights reserved.