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ENERGY BUDGET PRINCIPLES Radiation & Temperature Spring 2017

ENERGY BUDGET PRINCIPLES Radiation & Temperature Spring 2017. NRSM 532. Tropical forest. Desert. Montana. Energy (Temperature). Boreal forest. Tundra. Water. Potential climate limits to plant growth derived from long-term

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ENERGY BUDGET PRINCIPLES Radiation & Temperature Spring 2017

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  1. ENERGY BUDGET PRINCIPLESRadiation & TemperatureSpring 2017 NRSM 532

  2. Tropical forest Desert Montana Energy (Temperature) Boreal forest Tundra Water

  3. Potential climate limits to plant growth derived from long-term monthly statistics of minimum temperature, cloud cover and rainfall. Water = 40%, Temperature = 33%, Radiation = 27% Nemani et al. 2003 Running et al 2004

  4. Jolly, Nemani, Running. Global Change Biology 2005

  5. Russia, Boreal Seasonal Growing Season Constraints Africa, Savannah Jolly, Nemani, Running. Global Change Biology 2005

  6. Important Radiation Laws & Concepts Net radiation Rn = (1- )Is + EL T4(surface) - T4(sky) Surface Energy Balance Rn – G = H + E Bowen Ratio  = H / E

  7. Insolation: Solar Radiation Striking the earth’s Surface I = S cos(Z) I = insolation S ~ 1000 W m-2 (clear day solar insolation on a surface perpendicular to incoming solar radiation. This value actually varies greatly due to atmospheric variables.) Z = Zenith Angle (the angle from the zenith (point directly overhead) to the Sun’s position in the sky. The zenith angle is dependent upon latitude, solar declination angle, and time of day.

  8. Insolation: Zenith Angle Z = cos-1 {sin(Latitude) sin(Solar Decl.) + cos (Latitude) cos(Solar Decl.) cos H} Latitude = latitude at site of interest (Missoula ~46°) Solar Decl. = solar declination At Vernal Equinox (Mar. 21/22) = 0° At Summer Solstice (Jun. 21/22) = +23.5° At Autumnal Equinox (Sept. 21/22) = 0° At Winter Solstice (Dec. 21/22) = -23.5° H = hour angle = 15° X (Time – 12) This is the angle of radiation due to the time of day Time is given in solar time as the hour of day from midnight.

  9. Important Radiation Laws & Concepts Stefan-Boltzmann Law  = T4

  10. Important Radiation Laws & Concepts Wien’s Law m = 2897 / T

  11. Bowen Ratio  = H / E  = 10 / 1 = 10  = 10 / 100 = 0.1

  12. HOTTEST PLACES ON EARTH

  13. Relationship between LST andVegetation Cover

  14. Surface Temperature Extremes

  15. Land Water Balance And Surface Temperature

  16. Geographic Variation in Annual Water Balance (Precip - Potential ET, meters per year)

  17. PENMAN-MONTEITH equation for Evapotranspiration THE PROBLEM Temperature + Precipitation does NOT tell the integrated land water balance Windspeed 1-d Land Water Balance = Precipitation – Evapotranspiration Watershed Balance = Precip – (ET + Runoff) Air Temperature Solar radiation Humidity Veg Leaf Area

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