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Cryosphere snow and climate change

Cryosphere snow and climate change. Tao Wang Beijing university, 10 April, 2013. Outline. Snow properties Snow modeling Snow dynamics Snow impacts. Outline. Snow properties Snow modeling Snow dynamics Snow impacts.

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Cryosphere snow and climate change

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  1. Cryosphere snow and climate change Tao Wang Beijing university, 10 April, 2013

  2. Outline Snow properties Snow modeling Snow dynamics Snow impacts

  3. Outline Snow properties Snow modeling Snow dynamics Snow impacts

  4. Snow properties Snow albedo (snow grain size and snow impurity) Snow thermal conductivity (snow density)

  5. Snow properties What affects snow albedo Snow albedo snow grain size (age) snow impurity Snow depth and Sun angle

  6. Snow properties What affects snow albedo Snow albedo snow grain size (age) snow impurity Snow depth and Sun angle

  7. Snow properties - snow albedo Influence of snow grain sizes (Wiscombe & Warren, 1980)

  8. Snow properties What affects snow albedo Snow albedo snow grain size (age) snow impurity Snow depth and Sun angle

  9. Snow properties - snow albedo Impacts of soot on snow albedo (Wiscombe & Warren, 1980)

  10. Snow properties - snow albedo

  11. Snow properties – thermal conductivity Snow thermal conductivity What is snow thermal conductivity? Snow heat capacity Snow density

  12. Snow properties – thermal conductivity Snow thermal conductivity What is snow thermal conductivity? Snow heat capacity Snow density Importance of thermal conductivity Ground thermal regime Snow metamorphism -Determine temperature gradient -Determine vapor flux

  13. Snow properties – thermal conductivity Snow thermal conductivity What is snow thermal conductivity? Snow heat capacity Snow density Importance of thermal conductivity Ground thermal regime Snow metamorphism -Determine temperature gradient -Determine vapor flux determination of thermal conductivity: microstructure tomography; snow temperature profiles

  14. Snow properties – thermal conductivity Snow thermal conductivity – snow density snow thermal conductivity snow density

  15. Outline Snow properties Snow modeling Snow dynamics Snow impacts

  16. Snow modeling Lessons from Snow model intercomparisons and Ensembles

  17. Snow modeling Lessons from Snow model intercomparisons and Ensembles

  18. Snow modeling Example SnowMIP result from Col de Porte 23 models Essery et al. (2012) Why large differences between snow models?

  19. Snow modeling R1: Snow thermal conductivity parameterizations Quadratic function of density e.g. SAST, SNTHERN, CLM Power function of density e.g. Crocus, HTESSEL, ISBA-ES Constant e.g. MAPS, MOSES, ORCHIDEE

  20. Snow modeling R2: Snow albedo parameterizations Function of prognostic snow grain size Empirical function of age Function of surface temperature

  21. Snow modeling R3: Other parameterizations Snow compaction factors Snow cover fraction Fresh snow density Snow hydrology (liquid water holding capacity)

  22. Snow modeling ORCHIDEE-ES on Col de Porte Albedo-related Thermal conductivity-related Wang et al. (2013) Snow compaction factors

  23. Snow modeling Lessons from Snow model intercomparisons and Ensembles 1. Multiple snow layers 2. Snow density simulation 3. Snow albedo simulation

  24. Snow modeling ORCHIDEEvsORCHIDEE-ES 1. Single vs. Multiple snow layers 2. Constant vs. Time-varying snow density 3. Age-related but more realistic

  25. Snow modeling ORCHIDEE vs. ORCHIDEE-ES on Col de Porte Snow density comparison Wang et al. (2013)

  26. Snow modeling ORCHIDEE vs. ORCHIDEE-ES on Col de Porte SWE comparison Wang et al. (2013)

  27. Snow modeling ORCHIDEE vs. ORCHIDEE-ES on Col de Porte Soil temperature comparison Wang et al. (2013)

  28. Outline Snow properties Snow modeling Snow dynamics Snow impacts

  29. Snow dynamics Methods Field observations Remote-sensing Snow modeling Projections

  30. Snow dynamics Methods Field observations Remote-sensing Snow modeling

  31. Snow dynamics A list of papers…

  32. Snow dynamics Snow cover Days (satellite-derived) Difference between 1972/1973 and 2008/2009 AMAP (2012)

  33. Snow dynamics Snow cover Days (satellite-derived) Derksen et al. (2009) Difference between 1972/1973 and 2008/2009 AMAP (2012)

  34. Snow dynamics Snow cover Days (station-based) Derksen et al. (2009) Difference between 1972/1973 and 2008/2009 AMAP (2012) Peng et al. (2013)

  35. Snow dynamics Snow depth (high spatial heterogeneity) 1948-2006 (Jan-Mar) Park et al. (2012) Russia 1966-2007 (annual snow depth) China 1980-2005 (Dec-Feb) Bulygina et al. (2009) Peng et al. (2010)

  36. Snow dynamics Snow depth (high spatial heterogeneity) 1948-2006 (Jan-Mar) Park et al. (2012) Russia 1966-2007 (annual snow depth) China 1980-2005 (Dec-Feb) Why increase? Bulygina et al. (2009) Peng et al. (2010)

  37. Snow dynamics R1: Declining sea-ice extent ? Less sea-ice increasing evaporation more humid and snowfall further south

  38. Snow dynamics R2: Climate pattern? (Arctic oscillation)

  39. Snow dynamics R2: Climate pattern? (Arctic oscillation)

  40. Outline Snow properties Snow modeling Snow dynamics Snow Impacts

  41. Snow Impacts – albedo feedback Snow albedo feedback on climate How important? Correlation between annual-mean temperature response and springtime snow albedo feedback strength in North Hemisphere (Hall et al., 2007)

  42. Snow Impacts – albedo feedback How to quantify it? snow cover feedback: Ts increase lead to snow cover decrease, further resulting in albedo decrease snowpack metamorphosis feedback: Ts increase leads to snowpack albedo decease -1.06±0.08%/K A list of studies….

  43. Snow Impacts – albedo feedback How to constrain snow albedo feedback in model ? Option 1: Developing physical-based snow albedo scheme taking into account snow grain size, impurity content etc Albedo = f(snow age)

  44. Snow Impacts – albedo feedback How to constrain snow albedo feedback in model ? Option 1: Developing physical-based snow albedo scheme taking into account snow grain size, impurity content etc Albedo = f(snow age) Albedo = f(snow grain size, impurity, sun angle, snow depth)

  45. Snow Impacts – albedo feedback How to constrain snow albedo feedback in model ? Option 1: Developing physical-based snow albedo scheme taking into account snow grain size, impurity content etc Option 2: Data assimilation from albedo product (GlobAlbedo)

  46. Snow Impacts – albedo feedback How to constrain snow albedo feedback in model ? Option 1: Developing physical-based snow albedo scheme taking into account snow grain size, impurity content etc Option 2: Data assimilation from albedo product (GlobAlbedo) April Reflected radiation (albedo x SWdown) Control Assimil. Wang et al. (in prepare)

  47. Snow Impacts – carbon balance Snow and ecosystem carbon balance Early snowmelt -0.077 °C/day Peng et al. (2013) + Spring Temperature

  48. Snow Impacts – carbon balance Snow and ecosystem carbon balance Early snowmelt + Spring Temperature (longer GSL) + Ecosystem CO2 uptake

  49. Snow Impacts – carbon balance GSL-growing season NDVI in alpine grassland on the interannual timescale

  50. Snow Impacts – carbon balance Snow and ecosystem carbon balance Early snowmelt + Spring Temperature + Ecosystem CO2 uptake + ET + - Soil moisture

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