Improvement Test for the Canopy Interception Parameterization Scheme in the Community Land Model

Abstract

The Qian atmospheric forcing dataset is used to drive version 4.5 of the Community Land Model (CLM4.5) in off-line simulation tests. Based on the Global Land Evaporation Amsterdam Model (GLEAM) data, we attempt to ameliorate the canopy interception parameterization scheme in CLM4.5 by improving the empirical parameter and the physical structure. Considering that different plant functional types (PFTs) have different capacities to intercept rainfall is denoted as SEN1, and accounting for the influence of wind speed on canopy interception on the basis of SEN1 is denoted as SEN2. SEN1 shows obvious improvement in the simulated evaporation of intercepted water from vegetation canopy (Ec), not only greatly reduces the positive bias of the model to simulate Ec, especially in the equatorial region, but also significantly reduces the root mean square error (RMSE). SEN2 further improves the simulation of Ec by lowering the RMSE and increasing consistency with GLEAM data. In addition, the percentages of Ec over total evapotranspiration in both SEN1 and SEN2 are more reasonable and much closer to GLEAM data than that in CLM4.5.