@article{fdi:010079823,
  title = {{A}lleviation of an {A}rctic {S}ea ice bias in a coupled model through modifications in the subgrid-scale orographic parameterization},
  author = {{G}astineau, {G}. and {L}ott, {F}. and {M}ignot, {J}uliette and {H}ourdin, {F}.},
  editor = {},
  language = {{ENG}},
  abstract = {{I}n climate models, the subgrid-scale orography ({SSO}) parameterization imposes a blocked flow drag at low levels that is opposed to the local flow. {I}n {IPSL}-{CM}6{A}-{LR}, an {SSO} lift force is also applied perpendicular to the local flow to account for the effect of locally blocked air in narrow valleys. {U}sing {IPSL}-{CM}6{A}-{LR} sensitivity experiments, it is found that the tuning of both effects strongly impacts the atmospheric circulation. {I}ncreasing the blocking and reducing the lift lead to an equatorward shift of the {N}orthern {H}emisphere subtropical jet and a reduction of the midlatitude eddy-driven jet speed. {I}t also improves the simulated synoptic variability, with a reduced storm-track intensity and increased blocking frequency over {G}reenland and {S}candinavia. {A}dditionally, it cools the polar lower troposphere in boreal winter. {T}ransformed {E}ulerian {M}ean diagnostics also show that the low-level eddy-driven subsidence over the polar region is reduced consistent with the simulated cooling. {T}he changes are amplified in coupled experiments when compared to atmosphere-only experiments, as the low-troposphere polar cooling is further amplified by the temperature and albedo feedbacks resulting from the {A}rctic sea ice growth. {I}n {IPSL}-{CM}6{A}-{LR}, this corrects the warm winter bias and the lack of sea ice that were present over the {A}rctic before adjusting the {SSO} parameters. {O}ur results, therefore, suggest that the adjustment of {SSO} parameterization alleviates the {A}rctic sea ice bias in this case. {H}owever, the atmospheric changes induced by the parametrized {SSO} also impact the ocean, with an equatorward shift of the {N}orthern {H}emisphere oceanic gyres and a weaker {A}tlantic meridional overturning circulation.},
  keywords = {climate models ; orography ; atmospheric ; dynamics ; air-sea interaction ; {A}rctic {O}cean ; {ARCTIQUE}},
  booktitle = {},
  journal = {{J}ournal of {A}dvances in {M}odeling {E}arth {S}ystems},
  volume = {12},
  numero = {9},
  pages = {e2020{MS}002111 [19 p.]},
  year = {2020},
  DOI = {10.1029/2020ms002111},
  URL = {https://www.documentation.ird.fr/hor/fdi:010079823},
}