Improved representation of surface-groundwater interaction in the Canadian land surface scheme

2018 ◽  
Vol 38 (14) ◽  
pp. 5077-5094
Author(s):  
Arman Ganji ◽  
Laxmi Sushama
Keyword(s):  
Land Surface ◽  
Land Surface Scheme ◽  
Canadian Land Surface Scheme ◽  
Surface Scheme

scholarly journals Sensitivity tests of the Canadian Land Surface Scheme (CLASS) for Arctic tundra

1997 ◽  
Vol 25 ◽  
pp. 46-50 ◽  
Author(s):  
Jeffrey S. Tilley ◽  
William L. Chapman ◽  
Wanli Wu
Keyword(s):  
Land Surface ◽  
Initial Conditions ◽  
Soil Depth ◽  
Arctic Tundra ◽  
Systems Science ◽  
Initial Water ◽  
Land Surface Scheme ◽  
Internal Parameters ◽  
Canadian Land Surface Scheme ◽  
Surface Scheme

We have conducted tests of the Canadian Land Surface Scheme (CLASS V2.5) for Arctic tundra applications. Our tests emphasize sensitivities to initial conditions, external forcings and internal parameters, and focus on the Alaskan North Slope during the summer of 1992. Observational data from the National Science foundation (NSF), Arctic Systems Science (ARCSS), Land/Atmosphere/Ice Interactions (LAII) Flux Study is available to serve as forcing and validation for our simulations.Comparisons of the runs show strong sensitivities to the composition and depth of the soil layers, and we find that a minimum total soil depth of 5.0 m is needed to maintain permafrost. The response of the soil to diurnal variations in forcing is strong, while sensitivities to other internal parameters, as well as to precipitation, were relatively small. Some sensitivity to air temperatures and radiative fluxes, particularly the incoming shortwave flux, was also present. Significant sensitivity to the specification of the initial water and ice contents of the soil was found, while the sensitivity to initial soil temperature was somewhat less.

Parametrization of Peatland Hydraulic Properties for the Canadian Land Surface Scheme

2019 ◽  
pp. 93-105
Author(s):  
Matthew G. Letts ◽  
Nigel T. Roulet ◽  
Neil T. Comer ◽  
Michael R. Skarupa ◽  
Diana L. Verseghy
Keyword(s):  
Land Surface ◽  
Hydraulic Properties ◽  
Land Surface Scheme ◽  
Canadian Land Surface Scheme ◽  
Surface Scheme

scholarly journals Simulating shrubs and their energy and carbon dioxide fluxes in Canada's Low Arctic with the Canadian Land Surface Scheme Including biogeochemical Cycles (CLASSIC)

2020 ◽  
Author(s):  
Gesa Meyer ◽  
Elyn R. Humphreys ◽  
Joe R. Melton ◽  
Alex J. Cannon ◽  
Peter M. Lafleur
Keyword(s):  
Carbon Dioxide ◽  
Land Surface ◽  
Biogeochemical Cycles ◽  
Dwarf Shrub ◽  
Land Surface Scheme ◽  
Canadian Land Surface Scheme ◽  
Shrub Tundra ◽  
Flux Measurements ◽  
Surface Scheme ◽  
Process Based Models

Abstract. The Arctic is warming more rapidly than other regions of the world leading to ecosystem change including shifts in vegetation communities, permafrost degradation and alteration of tundra surface-atmosphere energy and carbon (C) fluxes, among others. However, year-round C and energy flux measurements at high-latitude sites remain rare. This poses a challenge for evaluating the impacts of climate change on Arctic tundra ecosystems and for developing and evaluating process-based models, which may be used to predict regional and global energy and C feedbacks to the climate system. Our study used 14 years of seasonal eddy covariance (EC) measurements of carbon dioxide (CO2), water and energy fluxes and winter soil chamber CO2 flux measurements at a dwarf-shrub tundra site underlain by continuous permafrost in Canada's Southern Arctic ecozone to evaluate the incorporation of shrub plant functional types (PFTs) in the Canadian Land Surface Scheme Including biogeochemical Cycles (CLASSIC), the land surface component of the Canadian Earth System Model. In addition to new PFTs, a modification of the efficiency with which water evaporates from the ground surface was applied. This modification addressed a high ground evaporation bias that reduced model performance when soils became very dry, limited heat flow into the ground and reduced plant productivity through water stress effects. Compared to the grass and tree PFTs previously used by CLASSIC to represent the vegetation in Arctic permafrost-affected regions, simulations with the new shrub PFTs better capture the physical and biogeochemical impact of shrubs on the magnitude and seasonality of energy and CO2 fluxes at the dwarf-shrub tundra evaluation site. The revised model, however, tends to overestimate gross primary productivity, particularly in spring, and overestimated late winter CO2 emissions. On average, annual net ecosystem CO2 exchange was positive for all simulations, suggesting this site was a net CO2 source of 18 ± 4 g C m−2 year−1 using shrub PFTs, 15 ± 6 g C m−2 year−1 using grass PFTs, and 25 ± 5 g C m−2 year−1 using tree PFTs. These results highlight the importance of using appropriate PFTs in process-based models to simulate current and future Arctic surface-atmosphere interactions.

scholarly journals On the Performance of the Canadian Land Surface Scheme Driven by the ERA5 Reanalysis over the Canadian Boreal Forest

2020 ◽  
Vol 21 (6) ◽  
pp. 1383-1404 ◽  
Author(s):  
M. Alves ◽  
D. F. Nadeau ◽  
B. Music ◽  
F. Anctil ◽  
A. Parajuli
Keyword(s):  
Surface Energy ◽  
Soil Temperature ◽  
Land Surface ◽  
Snow Depth ◽  
Water Fluxes ◽  
State Variables ◽  
Land Surface Scheme ◽  
Canadian Land Surface Scheme ◽  
Simulated Surface ◽  
Surface Scheme

AbstractThe Canadian Land Surface Scheme (CLASS) has been applied over the years in coupled and uncoupled (offline) modes at local, regional, and global scales using various forcing datasets. In this study, CLASS is applied at a local scale in the offline configuration to evaluate its performance when driven by the ERA5 reanalysis. Simulated surface energy fluxes, as well as several other water balance components, are investigated at four sites across the Canadian boreal biome. The results from CLASS driven by ERA5 (CLASS-RNL) are compared with available in situ measurements, as well as with results from CLASS driven by observations (CLASS-CTL). Additional simulations are conducted to evaluate the effects of biases in the ERA5 precipitation, where CLASS is forced by ERA5 data, but with ERA5 precipitation being replaced by observed precipitation (CLASS-RNL-ObsP). The results show that simulated surface variables in CLASS-RNL are in good agreement with observations as well as with those simulated in CLASS-CTL. The CLASS-RNL captures well the observed annual cycles of the surface energy and water fluxes, as well as the year-to-year variation of snow depth, soil temperature, and soil moisture. A strong correlation is found between the observed and CLASS-RNL simulated snow depth and soil temperature. Biases in the ERA5 precipitation did not affect the simulation of soil state variables, whereas the simulated surface heat and water fluxes, as well as the snow depth, were significantly affected. For instance, the simulated runoff in CLASS-RNL is much higher than in CLASS-RNL-ObsP and CLASS-CTL at the most humid sites due to significant positive bias in ERA5 precipitation.

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