CMIP5 model selection for ISMIP6 ice sheet model forcing: Greenland and Antarctica

Alice Barthel (1) , Cécile Agosta (2, 3) , Christopher Little (4) , Tore Hattermann (5) , Nicolas Jourdain (6) , Heiko Goelzer (7) , Sophie Nowicki (8) , Hélène Seroussi (9) , Fiammetta Straneo (10) , Thomas Bracegirdle (11)

1 LANL - Los Alamos National Laboratory
2 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
3 GLACCIOS - Glaces et Continents, Climats et Isotopes Stables
4 AER - Atmospheric and Environmental Research, Inc.
5 Norwegian Polar Institute
6 IGE - Institut des Géosciences de l’Environnement
7 IMAU - Institute for Marine and Atmospheric Research [Utrecht]
8 GSFC - NASA Goddard Space Flight Center
9 JPL - Jet Propulsion Laboratory
10 SIO - UC San Diego - Scripps Institution of Oceanography
11 BAS - British Antarctic Survey

The ice sheet model intercomparison project for CMIP6 (ISMIP6) effort brings together the ice sheet and climate modeling communities to gain understanding of the ice sheet contribution to sea level rise. ISMIP6 conducts stand-alone ice sheet experiments that use space-and time-varying forcing derived from atmosphere-ocean coupled global climate models (AOGCMs) to reflect plausible trajectories for climate projections. The goal of this study is to recommend a subset of CMIP5 AOGCMs (three core and three targeted) to produce forcing for ISMIP6 stand-alone ice sheet simulations , based on (i) their representation of current climate near Antarctica and Greenland relative to observations and (ii) their ability to sample a diversity of projected atmosphere and ocean changes over the 21st century. The selection is performed separately for Greenland and Antarc-tica. Model evaluation over the historical period focuses on variables used to generate ice sheet forcing. For stage (i), we combine metrics of atmosphere and surface ocean state (annual-and seasonal-mean variables over large spatial domains) with metrics of time-mean subsurface ocean temperature biases averaged over sectors of the continental shelf. For stage (ii), we maximize the diversity of climate projections among the best-performing models. Model selection is also constrained by technical limitations, such as availability of required data from RCP2.6 and RCP8.5 projections. The selected top three CMIP5 climate models are CCSM4, MIROC-ESM-CHEM, and NorESM1-M for Antarctica and HadGEM2-ES, MIROC5, and NorESM1-M for Greenland. This model selection was designed specifically for ISMIP6 but can be adapted for other applications.

Domaines: Océan, Atmosphère; Interfaces continentales, environnement

Alice Barthel, Cécile Agosta, Christopher Little, Tore Hattermann, Nicolas Jourdain, et al.. CMIP5 model selection for ISMIP6 ice sheet model forcing: Greenland and Antarctica. The Cryosphere, 2020, 14 (3), pp.855-879. ⟨10.5194/tc-14-855-2020⟩. ⟨hal-02524433⟩