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Title: The impact of changing the land surface scheme in ACCESS(v1.0/1.1) on the surface climatology

The Community Atmosphere Biosphere Land Exchange (CABLE) model has been coupled to the UK Met Office Unified Model (UM) within the existing framework of the Australian Community Climate and Earth System Simulator (ACCESS), replacing the Met Office Surface Exchange Scheme (MOSES). Here we investigate how features of the CABLE model impact on present-day surface climate using ACCESS atmosphere-only simulations. The main differences attributed to CABLE include a warmer winter and a cooler summer in the Northern Hemisphere (NH), earlier NH spring runoff from snowmelt, and smaller seasonal and diurnal temperature ranges. The cooler NH summer temperatures in canopy-covered regions are more consistent with observations and are attributed to two factors. Firstly, CABLE accounts for aerodynamic and radiative interactions between the canopy and the ground below; this placement of the canopy above the ground eliminates the need for a separate bare ground tile in canopy-covered areas. Secondly, CABLE simulates larger evapotranspiration fluxes and a slightly larger daytime cloud cover fraction. Warmer NH winter temperatures result from the parameterization of cold climate processes in CABLE in snow-covered areas. In particular, prognostic snow density increases through the winter and lowers the diurnally resolved snow albedo; variable snow thermal conductivity prevents early winter heatmore » loss but allows more heat to enter the ground as the snow season progresses; liquid precipitation freezing within the snowpack delays the building of the snowpack in autumn and accelerates snow melting in spring. Altogether we find that the ACCESS simulation of surface air temperature benefits from the specific representation of the turbulent transport within and just above the canopy in the roughness sublayer as well as the more complex snow scheme in CABLE relative to MOSES.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1]
  1. CSIRO Oceans and Atmosphere, Aspendale, VIC (Australia)
  2. CSIRO Oceans and Atmosphere, Yarralumla, ACT (Australia)
Publication Date:
Grant/Contract Number:
FG02-04ER63917; FG02-04ER63911
Type:
Accepted Manuscript
Journal Name:
Geoscientific Model Development (Online)
Additional Journal Information:
Journal Name: Geoscientific Model Development (Online); Journal Volume: 9; Journal Issue: 8; Journal ID: ISSN 1991-9603
Publisher:
European Geosciences Union
Research Org:
Oregon State Univ., Corvallis, OR (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES
OSTI Identifier:
1361530

Kowalczyk, Eva A., Stevens, Lauren E., Law, Rachel M., Harman, Ian N., Dix, Martin, Franklin, Charmaine N., and Wang, Ying -Ping. The impact of changing the land surface scheme in ACCESS(v1.0/1.1) on the surface climatology. United States: N. p., Web. doi:10.5194/gmd-9-2771-2016.
Kowalczyk, Eva A., Stevens, Lauren E., Law, Rachel M., Harman, Ian N., Dix, Martin, Franklin, Charmaine N., & Wang, Ying -Ping. The impact of changing the land surface scheme in ACCESS(v1.0/1.1) on the surface climatology. United States. doi:10.5194/gmd-9-2771-2016.
Kowalczyk, Eva A., Stevens, Lauren E., Law, Rachel M., Harman, Ian N., Dix, Martin, Franklin, Charmaine N., and Wang, Ying -Ping. 2016. "The impact of changing the land surface scheme in ACCESS(v1.0/1.1) on the surface climatology". United States. doi:10.5194/gmd-9-2771-2016. https://www.osti.gov/servlets/purl/1361530.
@article{osti_1361530,
title = {The impact of changing the land surface scheme in ACCESS(v1.0/1.1) on the surface climatology},
author = {Kowalczyk, Eva A. and Stevens, Lauren E. and Law, Rachel M. and Harman, Ian N. and Dix, Martin and Franklin, Charmaine N. and Wang, Ying -Ping},
abstractNote = {The Community Atmosphere Biosphere Land Exchange (CABLE) model has been coupled to the UK Met Office Unified Model (UM) within the existing framework of the Australian Community Climate and Earth System Simulator (ACCESS), replacing the Met Office Surface Exchange Scheme (MOSES). Here we investigate how features of the CABLE model impact on present-day surface climate using ACCESS atmosphere-only simulations. The main differences attributed to CABLE include a warmer winter and a cooler summer in the Northern Hemisphere (NH), earlier NH spring runoff from snowmelt, and smaller seasonal and diurnal temperature ranges. The cooler NH summer temperatures in canopy-covered regions are more consistent with observations and are attributed to two factors. Firstly, CABLE accounts for aerodynamic and radiative interactions between the canopy and the ground below; this placement of the canopy above the ground eliminates the need for a separate bare ground tile in canopy-covered areas. Secondly, CABLE simulates larger evapotranspiration fluxes and a slightly larger daytime cloud cover fraction. Warmer NH winter temperatures result from the parameterization of cold climate processes in CABLE in snow-covered areas. In particular, prognostic snow density increases through the winter and lowers the diurnally resolved snow albedo; variable snow thermal conductivity prevents early winter heat loss but allows more heat to enter the ground as the snow season progresses; liquid precipitation freezing within the snowpack delays the building of the snowpack in autumn and accelerates snow melting in spring. Altogether we find that the ACCESS simulation of surface air temperature benefits from the specific representation of the turbulent transport within and just above the canopy in the roughness sublayer as well as the more complex snow scheme in CABLE relative to MOSES.},
doi = {10.5194/gmd-9-2771-2016},
journal = {Geoscientific Model Development (Online)},
number = 8,
volume = 9,
place = {United States},
year = {2016},
month = {8}
}