Evaluation of the effect of low soil temperature stress on the land
surface energy fluxes simulation in the site and global offline
experiments
Abstract
Low soil temperature stress is a critical factor affecting the root
water uptake (RWU) rate of plants. In current land surface models, the
RWU amount is determined by the soil water extracted from different soil
layers, which calculates by the relative soil water availability and the
root fraction of each layer in the rooting zone. The effect of low soil
temperature stress is not considered, which may produce biases in the
simulation of transpiration. In this study, with the utilization of the
in-situ observation data from three FLUXNET sites, we introduced three
functions to represent the low soil temperature stress in the Common
Land Model (CoLM) and evaluated their effects on the energy fluxes
simulation. Then the three low soil temperature stress functions were
also evaluated in the global offline simulations by using the
FLUXNET-MTE (multi-tree ensemble) data. Results show that the default
CoLM overestimates the latent heat flux but underestimates the sensible
heat flux in the local spring and early summer at three study sites. By
incorporating the low soil temperature stress function into CoLM, the
bias in energy flux simulation is significantly reduced. The global
offline simulations indicate that considering the effect of low soil
temperature stress can improve the model performance on the simulating
of the latent heat flux in those high latitude areas. Therefore, we
recommend incorporating the effect of low soil temperature stress into
land surface models, which is beneficial to increasing the reliability
of the models’ results, especially over the cold regions.