Abstract:
The land surface model of the Chinese Academy of Sciences (CAS-LSM),
which includes lateral flow, water use, nitrogen discharge and river
transport, soil freeze thaw front dynamics, and urban planning, was
implemented into the Flexible Global Ocean-Atmosphere-Land System model
grid-point version 3 (CAS-FGOALS-g3). Simulations were conducted using
the land–atmosphere component setup of CAS-FGOALS-g3. The simulations
showed reasonable distributions of the land surface variables when
compared against observations (including reanalysis, merged data, remote
sensing, etc). In terms of the new capabilities, it was shown that
considering the groundwater lateral flow caused a deepening of the water
table depth of around 25–50 mm in North India, central USA, and Sahel.
Including the anthropogenic groundwater use also led to increased latent
heat fluxes of about 20 W∙m-2 in the aforementioned
three areas. Inclusion of the soil freeze thaw front (FTF) dynamics
enabled seasonal-variation simulations of the freeze and thaw processes,
and the FTF-derived permafrost extent was comparable to that seen in the
observations. The simulations conducted using the riverine nitrogen
transport and human activity schemes showed that major rivers around the
globe, including western Europe, eastern China, and the Midwest of the
USA experienced annual dissolved inorganic nitrogen (DIN) rates of
25–50 Gg∙N∙yr-1, which were accompanied by surface
water regulation DIN losses of around 28
mg∙N∙m-2∙yr-1 and DIN retention of
200–500 mg∙N∙m-2∙yr-1. The results
suggest that the model is a useful tool for studying the effects of
land-surface processes on the global climate, especially those
influenced by human interventions.