Spatial scale of climate processes

2. Macroclimate Mesoclimate Microclimate Nanoclimate Global Regional Local Organismal Spatial scale of climate processes

3. Picture of sun

5. Radiation • Shortwave (K): UV and visible • Longwave (L): Infra-red, heat

6. Energy in = Energy out 343 Watts/m2 Incoming radiation is mostly short wave (vis, NIR, UV) 31% reflected by clouds or surface

7. Energy in = Energy out 343 Watts/m2 Incoming radiation is mostly short wave (vis, NIR, UV) 31% reflected by clouds or surface 20% absorbed by clouds and atmosphere 49% absorbed by earth surface

8. Radiation absorption = increased T Longwave re-radiation

9. Energy emitted =   T4  = emissivity (0-1; black body-perfect radiator-equals 1)  = Stefan-Boltzman constant (5.67x10-8 watts m-2 k-4) T = Absolute temp of emitting object (K)

10. The “greenhouse” effect

11. Energy Losses from the earth’s surface 23% lost as latent heat flux water vapor 7% lost as sensible heat flux conduction, convection Remainder lost as outgoing longwave

12. At the ecosystem “surface”…

13. Clouds, gas Earth’s surface Sunshine Reflectance How warm is the sky relative to the land? Net radiation • Energy input to ecosystem (absorption) • Balance between • Input (long- and short-wave radiation) • Output (long- and short-wave radiation) Rnet = (Kin – Kout) + (Lin – Lout) = (1 – albedo)Kin +  (sky Tsky4- sur Tsur4) http://geography.uoregon.edu/envchange/clim_animations/#Global%20Energy%20Balance

14. Ecosystem characteristics that affect Rnet • Albedo • Surface temperature (diff. between sky and surface T) • Factors that modify surface T • Roughness: canopy structure cause mixing and cooling • Water

15. Net radiometer

16. kin kout Radiation budget of a douglas fir forest

17. Season

18. Disturbance

19. Canopy roughness

20. Energy partitioning Rnet = H + LE + G + S Rnet = net radiation H = sensible heat flux LE = evapotranspiration G = ground heat flux S = change in storage

21. S • Converted to chemical energy via Ps • Change in temperature of vegetation and soil • < 10% of Rnet in most ecosystems • Often ignored in studies of microclimate

22. G = Ground • Conductive heat loss from surface • Depends on: • Thermal conductivity of substance • Thermal gradient • Negligible in tropical and temperate systems, big at high latitudes and altitudes

23. LE = latent heat • Convective heat loss from surface • Evapotranspiration • Depends on vapor pressure gradient between ecosystem and atmosphere • Transfers water from ecosystem to atmosphere

24. H = sensible heat • Conductive and convective heat loss from the surface • Depends on: • T difference between surface and overlying air • Turbulence • Convective turbulence = eddies

25. Energy available for turbulent exchange (momentum) • Available energy = Rnet – (G + S) = H + LE • Bowen ratio: H/LE • inversely related to proportion of Rnet that drives water loss • Driven by water availability

27. Characterizing functional differences among ecosystems… • Albdeo • Bowen ratio

31. Lecture ended here