Role of vegetation in generation of mesoscale circulation

Abstract

A soil-vegetation module is incorporated into a two-dimensional mesoscale model for simulating mesoscale circulations that develop due to changes in surface characteristics. The model was verified by evaluating the diurnal changes of heat fluxes, surface temperature, soil moisture and soil water content with different vegetation covers using a one-dimensional version. Thermally induced mesoscale circulations between vegetated and bare soil areas are simulated with the two-dimensional model using three different types of bare soil adjacent to the vegetated area. The properties of the vegetation breeze, which are similar to that of a sea breeze, are investigated. The intensity of the vegetation breeze circulation is directly related to the characteristics of the bare soil. There is a strong relationship between surface fluxes and the intensity of the vegetation breeze circulation. More soil moisture is transferred to the atmosphere over the vegetated area than over the bare soil area. The effect of vegetation on planetary boundary layer (PBL) structure is presented by comparing the differences of turbulent kinetic energy (TKE), eddy diffusivity and boundary layer height between vegetated area and bare soil area. The effect of bare soil properties on PBL structure is also described.