1. 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

2. Program 2013 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)

3. Cryosphere: κρύος : cold 「さむい」 σφα ῖ ρα : 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 radiation Solar „constant“ Mean solar radiative flux at Earth r s :solar radius a e :mean distance between Earth and the sun B s :radiative energy flux through the surface of the sun (black body radiation at 5700 K: 6.28 · 10 7 Wm −2 ) Latest corrected value: S = 1362 Wm -2

11. Global mean solar radiation on the surface of the Earth A: Albedo (fraction of reflected solar radiation) (Earth: A=0.3) e: eccentricity of Earth orbit mean insolation: Area of circle: r 2  Surface area of sphere: 4 r 2 

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 =  T 4 with σ = 5.67×10 −8 W m −2 K −4 B=1368 W m −2  T=395 K (122 o C) B/4=342 W m −2  T=279 K (5 o C) 0.7 * B/4=239 W m −2  T=255 K (-18 o C)

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

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

21. hexagonal lattice phase diagram of ice

22. ice crystal halos

23. 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

24. 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

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

26. ice albedo feedback 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)

27. 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