Description of a land-air parameterization scheme (LAPS)

Abstract

A land-air parameterization scheme (LAPS) describes mass, energy and momentum transfer between the land surface and the atmosphere. The scheme is designed as a software package, and can be run as part of an atmospheric model or as a stand-alone model. A single layer approach is chosen for the physical and biophysical scheme background. The scheme has seven prognostic variables: three temperature variables (the canopy vegetation, soil surface and deep soil), one interception storage variable, and three soil moisture storage variables. In the scheme upper boundary conditions are used: air temperature, water vapor pressure, wind speed, radiation and precipitation at a reference level within the atmospheric boundary layer. The sensible and latent heat are calculated using resistance representation. The evaporation from the bare soil is parameterized using an 'α' scheme. The soil model part is designed as a three-layer model which is used to describe the vertical transfer of water in the soil.