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Arctic warming amplified by near-surface infrared radiation feedbacks R. Bintanja R. G. Graversen

Arctic warming amplified by near-surface infrared radiation feedbacks R. Bintanja R. G. Graversen W. Hazeleger Royal Netherlands Meteorological Institute (KNMI) The Netherlands. Surface temperature analyses. GISS. Arctic warming in observations. Arctic warming in ERA-int. MAM. DJF.

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Arctic warming amplified by near-surface infrared radiation feedbacks R. Bintanja R. G. Graversen

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  1. Arctic warming amplified by near-surface infrared radiation feedbacks R. Bintanja R. G. Graversen W. Hazeleger Royal Netherlands Meteorological Institute (KNMI) The Netherlands

  2. Surface temperature analyses GISS Arctic warming in observations

  3. Arctic warming in ERA-int MAM DJF JJA SON Screen and Simmonds (2010)

  4. Arctic amplification in models Holland & Bitz, 2003 EC-Earth(IFS, NEMO, LIM)

  5. Feedbacks/processes that govern Arctic amplification (AA) – Ice-albedo feedback (snow, sea ice) – Longwave cooling (related to near-surface inversion) – Horizontal transport of (latent) heat – Evaporation – Clouds – Vegetation – …

  6. The amplifying effect of longwave cooling LW-cooling TOA Warming Warming LW-cooling is due to the temperature profile (among other things)

  7. Where does OLR come from? A 1-D radiative transfer model

  8. Climatological inversion strength Inversion Does the presence of the Arctic inversion amplify surface warming through infrared trapping?

  9. OLR (1 – e) Ls Latm Atmosphere Surface OLR = Surface part + Atmospheric part = (1 – e) Ls + Latm

  10. Fits of OLR against Ls… …provide the slope (1-e) and the axis intercept (Latm)

  11. 2 x CO2 T2m (global) 1 x CO2 44 years LW components (DJF) EC-Earth – 1 x CO2 control – 2 x CO2 (instantaneous) 70-80N 80-90N ERA & NCEP Difference between 1990-1999 and 2000-2009

  12. LAup = LAup + LAdown Atmospheric cooling efficiency LAup 30 40 50 60 70 90 80 LAdown Change in  Inversion strength (K)

  13. Concluding remarks – Arctic LW cooling ‘hampered’ by near-surface inversion – Inversion layer ‘traps’ longwave radiation, amplifying surface warming – LW-inversion feedback is positive – Inversion will change due to surface warming, altering the feedback strength

  14. Thank you for your attention

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