Tropical peatlands are among the most carbon-dense ecosystems on Earth,
and their water storage dynamics strongly control these carbon stocks.
The hydrological functioning of tropical peatlands differs from that of
northern peatlands, which has not yet been accounted for in global land
surface models (LSMs). Here, we integrated tropical peat-specific
hydrology modules into a global LSM for the first time, by utilizing the
peatland-specific model structure adaptation (PEATCLSM) of the NASA
Catchment Land Surface Model (CLSM). We developed literature-based
parameter sets for natural (PEATCLSMTrop,Nat) and
drained (PEATCLSMTrop,Drain) tropical peatlands. The
operational CLSM version (which includes peat as a soil class) and
PEATCLSMTrop,Nat were forced with global meteorological
input data and evaluated over the major tropical peatland regions in
Central and South America, the Congo Basin, and Southeast Asia.
Evaluation against a unique and extensive data set of in situ water
level and eddy covariance-derived evapotranspiration showed an overall
improvement in bias and correlation over all three study regions. Over
Southeast Asia, an additional simulation with
PEATCLSMTrop,Drain was run to address the large fraction
of drained tropical peatlands in this region.
PEATCLSMTrop,Drain outperformed both CLSM and
PEATCLSMTrop,Nat over drained sites. Despite the overall
improvements of both tropical PEATCLSM modules, there are strong
differences in performance between the three study regions. We attribute
these performance differences to regional differences in accuracy of
meteorological forcing data, and differences in peatland hydrologic
response that are not yet captured by our model.