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Irina Gorodetskaya, Hubert Gall é e, Gerhard Krinner Laboratoire de Glaciologie et G é ophysique

Present and Future Antarctic climate simulations using Mod èle Atmosphérique Régional forced with LMDZ GCM. Irina Gorodetskaya, Hubert Gall é e, Gerhard Krinner Laboratoire de Glaciologie et G é ophysique de l’Environnement, Grenoble,France. MOCA, Montreal 23 July, 2009.

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Irina Gorodetskaya, Hubert Gall é e, Gerhard Krinner Laboratoire de Glaciologie et G é ophysique

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  1. Present and Future Antarctic climate simulations using Modèle Atmosphérique Régional forced with LMDZ GCM Irina Gorodetskaya, Hubert Gallée, Gerhard Krinner Laboratoire de Glaciologie et Géophysique de l’Environnement, Grenoble,France MOCA, Montreal 23 July, 2009

  2. Antarctica warming? sfc temperature from IR sat data mean annual trends 1969-2000 mean annual trends 1957-2006 Steig et al 2009

  3. Changes in precipitation? Linear trends of annual snowfall accumulation (mm yr -1 decade -1) for 1955-2004 Monaghan et al 2008

  4. Surface mass balance from a GCM:Laboratoire de Meteorologie Dynamique general circulation model (LMDZ) 1981-2000 (S20) mmwe Krinner et al. 2007

  5. Ratio between simulated SMB in S20 and estimates by Vaughan et al. 1999 Ratio between LMDZ-simulated SMB and observed SMB in selected locations Krinner et al. 2007

  6. SMB components: LMDZ 1981-2000 mmwe Sublimation/ deposition Precip Melt Krinner et al. 2007

  7. Large-scale model (ECMWF or GCM) Nesting: MAR forced with LMDZ output Mesoscale model (MAR)

  8. Snow HCond FL T4 HLat FS HSen coupling to sea ice, land ice, vegetation...  HMelt HFreez Blowingsnow     FS        Tsfc Liquid water Percolation Atmospheric model: mesoscale hydrostatic primitive equation model (Gallée 1994, 1995) • Terrain following vertical coordinates (normalized pressure) • Turbulence: 1 1/2 closure (Duynkerke 1988) • Bulk cloud microphysics (Kessler 1962 and Lin et al 1983 + improvements of Meyers et al. 1992 and Levkov et al. 1992) • Solar and infrared radiative transfer scheme (Morcrette 2002, Ebert and Curry 1992) • Snow fall included into infrared radiation scheme Snow model: conservation of heat and water (solid and liquid), description of snow properties (density, dendricity, sphericity and size of the grains), melting/freezing Blowing snow model (Gallée et al, 2001) Modèle Atmosphérique Régional (MAR) • Horizontal resolution 40 km • 33 vertical levels (lowest ~9m, one level each 10 m below 50 m; top = 10hPa) • Initial and boundary conditions: LMDZ4

  9. MAR validation : Dome C (ECMWF forcing) Surface air temperature over Dome C, East Antarctica Gallée and Gorodetskaya, Clim Dyn 2008

  10. Model validation : South Pole (ECMWF forcing) Power spectrum (units2/time) Town, Gorodetskaya, Walden, Warren, in prep

  11. Snow accumulation at South Pole (MAR forced with ERA-40) Integrated snow,mm.w.e Snow accumulation, mm.w.e warm events PSCs 54% 24% 7% 4% 11% Gorodetskaya, Town, Gallée, in prep 1994

  12. MAR forced with LMDZ vs LMDZ itself : MAR - larger amplitude! r=0.6

  13. Annual mean precipitation: MAR(lmdz forced) - LMDZ 1980-1985 LMDZ: only snow fall (no erosion) MAR: precip-erosion(blowing snow parameterization) mmwe

  14. Surface mass balance: MAR (lmdz forced) 1982 mmwe

  15. Sublimation/deposition Snow fall minus erosion Blowing snow flux Melt SMB components: MAR (lmdz forced)1982 units: mmwe

  16. Diff: 2082-1982 MAR forced with LMDZ SMB changes: from 1982 to 2082 Ratio: 2082/1982 mmwe

  17. Relative annual mean precipitation change: LMDZ (IPSL): 2081-2100 / 1981-2000 MAR (lmdz forced): 2082 / 1982 Krinner et al. 2007

  18. MAR forced with LMDZ Annual mean surface temperature change: 2082-1982 Precipitation change: 2082/1982 ratio

  19. Annual mean sea ice concentration changeLMDZ [2081-2100] - [1981-2000] % Krinner et al. 2007

  20. Conclusions • Modeling Antarctic surface mass balance and • precipitation in particular is challenging... • LMDZ and MAR : reasonable performance • High spatial variability in the future changes • in SMB and temperature simulated by LMDZ and • MAR forced with LMDZ • MAR: local differences compared with LMDZ • (blowing snow parameterization => snow redistribution, • larger amplitude synoptic-scale variability in temperature, • humidity and precip) • Different spatial pattern in future T and precip predicted • for the end of 21st century compared to recent changes Gorodetskaya, Gallée, Krinner MOCA-09, Montreal

  21. Thank you! Comments welcome: iragor@lgge.obs.ujf-grenoble.fr 1982->2082 ? 1957-2006 1982->2082 1955-2004 ?

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