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Cryospheric sciences 寒冷圏 科学 Heinz Blatter presently: ILTS, Hokkaido University, Sapporo

Cryospheric sciences 寒冷圏 科学 Heinz Blatter presently: ILTS, Hokkaido University, Sapporo. Special lecture on cryospheric Science International Antarctic Institute Graduate School of Environmental Science Hokkaido University, Sapporo. Fridays, 16.30-18.00

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Cryospheric sciences 寒冷圏 科学 Heinz Blatter presently: ILTS, Hokkaido University, Sapporo

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  1. Cryospheric sciences寒冷圏 科学Heinz Blatterpresently: ILTS, Hokkaido University, Sapporo Special lecture on cryospheric Science International Antarctic Institute Graduate School of Environmental Science Hokkaido University, Sapporo

  2. Fridays, 16.30-18.00 October 18: Cryosphere and climate October 25: Land ice and snow November 1: Sea ice November 8: Glaciers November 22: Ice sheets November 29: Past of the cryosphere December 6: Future of the cryosphere ftp://iacftp.ethz.ch/pub_read/blatter/IAI-2013/ ppt and pdf files are available (see subdirectories) Program 2013

  3. Cryosphere: κρύος: cold 「さむい」 σφαῖρα: sphere 「球、圏」 glaciers　「氷河」, ice sheets　「氷床」 permafrost　「永久凍土」 sea ice　「海氷」, lake ice　「湖氷」, river ice　「川氷」 snow 「雪」 ice clouds　「氷の雲」, hail　「氷雨」 hoar frost　「霧氷」

  4. Climate system • Atmosphere: • thermodynamics, wind, clouds, precipitation • Hydrosphere (ocean): • heat transport, evaporation, roughness • Pedosphere (solid Earth surface): • surface fluxes of heat, momentum, water • Biosphere: • surface fluxes, evapotranspiration Where is the cryosphere?

  5. Cryosphere • integral part of the climate system • many different sub-systems • many different processes • strong feedback mechanisms • strong influence to • atmospheric dynamics and precipitation • ocean surface energy exchange • terrestrial water balance this lecture presents an individual selection of topics: a physicists view

  6. processes: • dynamics: • wind, convection, ocean currents • thermodynamics: • insolation: surface, atmosphere, ocean • thermal radiation: „greenhouse effect“ • surface energy flux • meridional energy transport in atmosphere and ocean • weather: • clouds and precipitation (rain, snow, hail)

  7. schematic of the climate system IPCC

  8. Weather vs. Climate • weather: transient situation, days to weeks • climate: mean state of the climate system, mostly atmosphere • averaging time 30 years • high temporal and spatial variability on time scales of 2, 5-10, 50-1000, 20‘000-400‘000, millions of years and longer • gap around 30 years

  9. spectrum of periodic variabilities of climate

  10. Solar „constant“ Mean solar radiative flux at Earth rs: solar radius ae: mean distance between Earth and the sun Bs: radiative energy flux through the surface of the sun (black body radiation at 5700 K: 6.28 · 107 Wm−2) Latest corrected value: S = 1362 Wm-2 Solar radiation

  11. A: Albedo (fraction of reflected solar radiation) (Earth: A=0.3) e: eccentricity of Earth orbit mean insolation: Global mean solar radiation on the surface of the Earth Area of circle: r2p Surface area of sphere: 4r2p

  12. Global mean energy fluxes

  13. seasonal variation of daily insolation in percent of the solar constant S=1362 W m−2

  14. Radiation laws Stefan-Boltzmann law: B = s T4with σ = 5.67×10−8 W m−2 K−4 B=1368 W m−2 T=395 K (122oC) B/4=342 W m−2 T=279 K (5oC) 0.7*B/4=239 W m−2 T=255 K (-18oC)

  15. Radiation in the planetary system ``solar constant``: S proportional to 1/r 2 Temperature: T proportional to S1/4 T proportional to 1/r1/2

  16. radiation temperature in the planetary system

  17. Venus, Earth, Mars • Venus: runaway greenhouse, only vapor • Earth: water in all three phases • Mars: runawy icehouse, only ice

  18. Ice • solid state of water • anomalies: • ice floats on water (expansion at freezing) • melting point decreases with pressure

  19. hexagonal lattice phase diagram of ice

  20. ice crystal halos

  21. role of ice in the climate system • Albedo: most important • albedo: reflectivity of solar spectrum • snow and ice have high albedo • strong positive feedback • latent heat flux • melt and freezing: snow, sea ice, land ice • sublimation: high altitude • crystallisation: ice clouds

  22. albedo:fraction of reflected sunlight • rock: 0.1 • forest: 0.1-0.2 • ocean: 0.05 • desert: <0.3 • snow: 0.4-0.9 • glacier ice: 0.3-0.5

  23. controll circuit negative feedback: perturbation is damped positive feedback: perturbation is enhanced ice albedo feedback氷のアルベドの帰還

  24. example: large closed snow cover in Eurasia, longer winter example: decrease of sea ice cover in arctic ocean more absorption of solar radiation warmer in arctic ocean further decrease of sea ice cover polar climate more sensitive to changes in radiative forcing (greenhouse) ice albedo feedback

  25. summary • cryosphere is an important part of the climate system • snow and ice play an important role in many fundamental processes in the climate system as Goethe already mentioned 200 years ago: ice is more important than you think

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