The Alpine snow-albedo feedback in regional climate models

The effect of the snow-albedo feedback (SAF) on 2m temperatures and their future changes in the European Alps is investigated in the ENSEMBLES regional climate models (RCMs) with a focus on the spring season. A total of 14 re-analysis-driven RCM experiments covering the period 1961–2000 and 10 GCM-driven transient climate change projections for 1950–2099 are analysed. A positive springtime SAF is found in all RCMs, but the range of the diagnosed SAF is large. Results are compared against an observation-based SAF estimate. For some RCMs, values very close to this estimate are found; other models show a considerable overestimation of the SAF. Net shortwave radiation has the largest influence of all components of the energy balance on the diagnosed SAF and can partly explain its spatial variability. Model deficiencies in reproducing 2m temperatures above snow and ice and associated cold temperature biases at high elevations seem to contribute to a SAF overestimation in several RCMs. The diagnosed SAF in the observational period strongly influences the estimated SAF contribution to twenty first century temperature changes in the European Alps. This contribution is subject to a clear elevation dependency that is governed by the elevation-dependent change in the number of snow days. Elevations of maximum SAF contribution range from 1500 to 2000 m in spring and are found above 2000 m in summer. Here, a SAF contribution to the total simulated temperature change between 0 and 0.5 °C until 2099 (multi-model mean in spring: 0.26 °C) or 0 and 14 % (multi-model mean in spring: 8 %) is obtained for models showing a realistic SAF. These numbers represent a well-funded but only approximate estimate of the SAF contribution to future warming, and a remaining contribution of model-specific SAF misrepresentations cannot be ruled out.

[1]  Jessica D. Lundquist,et al.  Temperature trends at high elevations: Patterns across the globe , 2008 .

[2]  M. Winton.  Surface Albedo Feedback Estimates for the AR4 Climate Models , 2006 .

[3]  D. Lawrence,et al.  The contribution of snow condition trends to future ground climate , 2010 .

[4]  T. Mauritsen,et al.  Polar Amplification in CCSM4: Contributions from the Lapse Rate and Surface Albedo Feedbacks , 2014 .

[5]  C. Schär,et al.  Heavy precipitation in a changing climate: Does short‐term summer precipitation increase faster? , 2015 .

[6]  D. Lüthi,et al.  Elevation gradients of European climate change in the regional climate model COSMO-CLM , 2012, Climatic Change.

[7]  A. Hense,et al.  The Regional Climate Model COSMO-CLM (CCLM) , 2008 .

[8]  Simon C. Scherrer,et al.  Revisiting Swiss temperature trends 1959–2008 , 2012 .

[9]  Matteo Buzzi,et al.  Challenges in operational numerical weather prediction at high resolution in complex terrain , 2008 .

[10]  M. Schneebeli,et al.  Long‐term snow climate trends of the Swiss Alps (1931–99) , 2003 .

[11]  C. Marty.  Regime shift of snow days in Switzerland , 2008 .

[12]  J. Houghton,et al.  Climate Change 2013 - The Physical Science Basis: Working Group I Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change , 2014 .

[13]  J. Peixoto,et al.  Physics of climate , 1992 .

[14]  Jeffrey R. Key,et al.  Controls on Northern Hemisphere snow albedo feedback quantified using satellite Earth observations , 2009 .

[15]  Pierre Etchevers,et al.  An Intercomparison of Three Snow Schemes of Varying Complexity Coupled to the Same Land Surface Model: Local-Scale Evaluation at an Alpine Site , 2001 .

[16]  R. Colman,et al.  A comparison of climate feedbacks in general circulation models , 2003 .

[17]  Rolf Weingartner,et al.  Snow variability in the Swiss Alps 1864–2009 , 2013 .

[18]  R. Barry,et al.  Atmosphere, Weather and Climate , 1968 .

[19]  Sven Kotlarski,et al.  Alpine snow cover in a changing climate: a regional climate model perspective , 2013, Climate Dynamics.

[20]  C. Schär,et al.  Evaluation of the convection‐resolving regional climate modeling approach in decade‐long simulations , 2014 .

[21]  C. Appenzeller,et al.  Snow-albedo feedback and Swiss spring temperature trends , 2012, Theoretical and Applied Climatology.

[22]  Henry F. Diaz,et al.  Projected temperature changes along the American cordillera and the planned GCOS network , 2004 .

[23]  Daniela JacobJuliane,et al.  EURO-CORDEX: new high-resolution climate change projections for European impact research , 2013 .

[24]  Christof Appenzeller,et al.  Monitoring climate at Jungfraujoch in the high Swiss Alpine region. , 2008, The Science of the total environment.

[25]  D. Lawrence,et al.  Parameterization improvements and functional and structural advances in Version 4 of the Community Land Model , 2011 .

[26]  R. Armstrong,et al.  Snow and Climate: Physical Processes, Surface Energy Exchange and Modeling , 2010 .

[27]  Roger G. Barry,et al.  The Global Cryosphere: The terrestrial cryosphere , 2011 .

[28]  Atsumu Ohmura,et al.  Physical Basis for the Temperature-Based Melt-Index Method , 2001 .

[29]  A. Sterl,et al.  The ERA‐40 re‐analysis , 2005 .

[30]  D. Lüthi,et al.  The elevation dependency of 21st century European climate change: an RCM ensemble perspective , 2015 .

[31]  R. Vautard,et al.  EURO-CORDEX: new high-resolution climate change projections for European impact research , 2014, Regional Environmental Change.

[32]  H. Fowler,et al.  Heavier summer downpours with climate change revealed by weather forecast resolution model , 2014 .

[33]  Roberta Pirazzini,et al.  Challenges in Snow and Ice Albedo Parameterizations , 2009 .

[34]  B. Soden,et al.  An Assessment of Climate Feedbacks in Coupled Ocean–Atmosphere Models , 2006 .

[35]  Jouni Räisänen,et al.  21st Century changes in snow climate in Northern Europe: a high-resolution view from ENSEMBLES regional climate models , 2012, Climate Dynamics.

[36]  C. Tebaldi,et al.  Long-term Climate Change: Projections, Commitments and Irreversibility , 2013 .

[37]  R. Vautard,et al.  Regional climate modeling on European scales: a joint standard evaluation of the EURO-CORDEX RCM ensemble , 2014 .

[38]  P. Linden,et al.  ENSEMBLES: Climate Change and its Impacts - Summary of research and results from the ENSEMBLES project , 2009 .

[39]  K. Taylor,et al.  Interpretation of Snow-Climate Feedback as Produced by 17 General Circulation Models , 1991, Science.

[40]  A. Hall,et al.  What Controls the Strength of Snow-Albedo Feedback? , 2007 .

[41]  Roger G. Barry,et al.  The Global Cryosphere: Acknowledgements , 2011 .

[42]  A. Hall.  The role of surface albedo feedback in climate , 2004 .

[43]  C. Appenzeller,et al.  Trends in Swiss Alpine snow days: The role of local‐ and large‐scale climate variability , 2004 .

[44]  James W. Hurrell,et al.  Elevation Dependency of the Surface Climate Change Signal: A Model Study , 1997 .

[45]  H. Fowler,et al.  Elevation-dependent warming in mountain regions of the world , 2015 .