@article{fdi:010079365,
  title = {{IPSL}-{CM}5{A}2-an {E}arth system model designed for multi-millennial climate simulations},
  author = {{S}epulchre, {P}. and {C}aubel, {A}. and {L}adant, {J}. {B}. and {B}opp, {L}. and {B}oucher, {O}. and {B}raconnot, {P}. and {B}rockmann, {P}. and {C}ozic, {A}. and {D}onnadieu, {Y}. and {D}ufresne, {J}. {L}. and {E}stella-{P}erez, {V}. and {E}the, {C}. and {F}luteau, {F}. and {F}oujols, {M}. {A}. and {G}astineau, {G}. and {G}hattas, {J}. and {H}auglustaine, {D}. and {H}ourdin, {F}. and {K}ageyama, {M}. and {K}hodri, {M}yriam and {M}arti, {O}. and {M}eurdesoif, {Y}. and {M}ignot, {J}uliette and {S}arr, {A}. {C}. and {S}ervonnat, {J}. and {S}wingedouw, {D}. and {S}zopa, {S}. and {T}ardif, {D}.},
  editor = {},
  language = {{ENG}},
  abstract = {{B}ased on the fifth phase of the {C}oupled {M}odel {I}ntercomparison {P}roject ({CMIP}5)-generation previous {I}nstitut {P}ierre {S}imon {L}aplace ({IPSL}) {E}arth system model, we designed a new version, {IPSL}-{CM}5{A}2, aiming at running multi-millennial simulations typical of deep-time paleoclimate studies. {T}hree priorities were followed during the setup of the model: (1) improving the overall model computing performance, (2) overcoming a persistent cold bias depicted in the previous model generation and (3) making the model able to handle the specific continental configurations of the geological past. {T}hese developments include the integration of hybrid parallelization {M}essage {P}assing {I}nterface - {O}pen {M}ulti-{P}rocessing ({MPI}-{O}pen{MP}) in the atmospheric model of the {L}aboratoire de {M}eteorologic {D}ynamique ({LMDZ}), the use of a new library to perform parallel asynchronous input/output by using computing cores as "{I}/{O} servers" and the use of a parallel coupling library between the ocean and the atmospheric components. {T}he model, which runs with an atmospheric resolution of 3.75 degrees x 1.875 degrees and 2 to 0.5 degrees in the ocean, can now simulate similar to 100 years per day, opening new possibilities towards the production of multi-millennial simulations with a full {E}arth system model. {T}he tuning strategy employed to overcome a persistent cold bias is detailed. {T}he confrontation of a historical simulation to climatological observations shows overall improved ocean meridional overturning circulation, marine productivity and latitudinal position of zonal wind patterns. {W}e also present the numerous steps required to run {IPSL}-{CM}5{A}2 for deep-time paleoclimates through a preliminary case study for the {C}retaceous. {N}amely, specific work on the ocean model grid was required to run the model for specific continental configurations in which continents are relocated according to past paleogeographic reconstructions. {B}y briefly discussing the spin-up of such a simulation, we elaborate on the requirements and challenges awaiting paleoclimate modeling in the next years, namely finding the best trade-off between the level of description of the processes and the computing cost on supercomputers.},
  keywords = {},
  booktitle = {},
  journal = {{G}eoscientific {M}odel {D}evelopment},
  volume = {13},
  numero = {7},
  pages = {3011--3053},
  ISSN = {1991-959{X}},
  year = {2020},
  DOI = {10.5194/gmd-13-3011-2020},
  URL = {https://www.documentation.ird.fr/hor/fdi:010079365},
}