Effects of organic soil in the Noah-MP land-surface model on simulated skin and soil temperature profiles and surface energy exchanges for China

Abstract

Inclusion of the thermal and hydraulic effect of soil organic matter plays an important role in land-surface models (LSMs) for simulating soil temperature and surface energy exchanges. The current officially released Noah with multiparameterization (Noah-MP) LSM, implemented in the community Weather Research and Forecasting (WRF) model, does not include a parameterization for soil organic matter. In this study, the thermal and hydraulic effect of soil organic matter was parameterized into Noah-MP LSM. Based on the profiled soil organic matter data for China and the observations of skin temperature and soil temperature profiles from more than 2000 surface meteorological stations, we investigated the effects of organic soil using the Noah-MP LSM with and without the profiled soil organic matter at the regional scales. Compared with the simulation without the inclusion of organic soil parameterization, the Noah-MP LSM simulation with the profiled soil organic matter improved the skin temperature and soil temperature profiles, especially soil temperature in deep soils under cold and arid regions. The realistic representation of snow depth and the snow insulation dependency on snow depth were confirmed to be a pre-requisite in Noah-MP in the high latitudes. By incorporating the profiled soil organic matter, the Noah-MP LSM enlarged the regional mean sensible heat flux (SH) and lower the regional mean latent heat flux (LH). In the warm and humid regions, a relatively smaller effect of organic soil on soil temperature could lead to a larger effect on SH and LH, especially LH.