Evaluating the performance of the Canadian Land Surface Scheme Including
Biogeochemical Cycles (CLASSIC) tailored to the pan-Canadian domain
Abstract
Canada’s boreal forests and tundra ecosystems are responding to
unprecedented climate change with implications for the global carbon (C)
cycle and global climate. However, our ability to model the response of
Canada’s terrestrial ecosystems to climate change is limited and there
has been no comprehensive, process-based assessment of Canada’s
terrestrial C cycle. We tailor the Canadian Land Surface Scheme
Including Biogeochemical Cycles (CLASSIC) to Canada and evaluate its C
cycling performance against independent reference data. We utilize skill
scores to assess model performance against reference data alongside
benchmark scores that quantify the level of agreement between the
reference data sets to aid in interpretation. Our results demonstrate
CLASSIC’s sensitivity to prescribed vegetation cover. They also show
that the addition of five region-specific PFTs improves CLASSIC’s skill
at simulating the Canadian C cycle. CLASSIC performs well when tailored
to Canada, falls within the range of the reference data sets, and meets
or exceeds the benchmark scores for most C cycling processes. New
region-specific land cover products, well-informed plant functional type
(PFT) parameterizations, and more detailed reference data sets will
facilitate improvements to the representation of the terrestrial C cycle
in regional and global land surface models (LSMs). Incorporating a
parameterization for boreal disturbance processes and explicitly
representing peatlands and permafrost soils will improve CLASSIC’s
future performance in Canada and other boreal regions. This is an
important step toward a comprehensive process-based assessment of
Canada’s terrestrial C cycle and evaluating Canada’s net C balance under
climate change.