Development of the minimal advanced treatments of surface interaction and runoff

Abstract

A land surface model (LSM), minimal advanced treatments of surface interaction and runoff (MATSIRO), has been developed for climate studies at the global and regional scales. The canopy has a single layer, whose albedo and bulk coefficients are evaluated on the basis of a multilayer canopy model. The fluxes are calculated from the energy balance at the ground and canopy surfaces in snow-free and snow-covered portions considering the subgrid snow distribution. The interception evaporation from canopy and the transpiration on the basis of photosynthesis are treated. A simplified TOPMODEL is used to calculate runoff. The snow has the variable number of layers from one to three in accordance with snow water equivalent (SWE), and the snow temperature is calculated by a thermal conduction equation. Besides, the snowmelt, the refreeze of snowmelt, and the freeze of rainfall in snow are taken into consideration. It is found in the PILPS 2e experiment that some parameters in the runoff scheme, such as the surface hydraulic conductivity and the river channel fraction, have a considerable impact on the partitioning of the surface runoff and the base flow. The snow albedo is prognosticated from the time passage since last snowfall and the snow temperature. The soil has five layers in this version, and the soil temperature, the soil moisture, and the frozen amount of moisture are calculated.