surface energy budget
DESCRIPTION
Surface Energy Budget. R = - (G + H + L ) R = net solar and terrestrial radiation at the earth’s surface (+ into surface) Absorbed solar radiation (incoming – reflected) Incoming longwave radiation emitted by gases and clouds in the atmosphere - PowerPoint PPT PresentationTRANSCRIPT
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Surface Energy Budget• R = - (G + H + L )• R = net solar and terrestrial radiation at the earth’s
surface (+ into surface)– Absorbed solar radiation (incoming – reflected)– Incoming longwave radiation emitted by gases and clouds in
the atmosphere– Outgoing longwave radiation emitted by the earth’s surface
• G- storage of energy into the deep soil (- into soil)• H – heat flux into atmosphere(- into atm)• L – Latent heat flux into atmosphere ( - into atm)
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Heat StorageSpecific heat (j/(kg K)
Density (kg/m3) Heat storage per unit volume per K
Soil inorganic 733 2600 1.9x106
Soil inorganic 1921 1300 2.5x106
Water 4182 1000 4.2x106
Air 1004 1.2 1.2x103
Hartmann (1994)
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Soil Temperature
• high intensity of solar radiation at high altitudes can result in high surface temperature
• Austria- 80C humus at 2070 m; air temp at 2 m 30C
• New Guinea 60C at 3480 m air temp 15C
Barry (1992)
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Net Radiation
Whiteman (2000)
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Surface Energy Budget
Whiteman (2000)
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Surface Energy Budget
Whiteman (2000)
![Page 7: Surface Energy Budget](https://reader035.vdocuments.site/reader035/viewer/2022062309/568134fe550346895d9c4936/html5/thumbnails/7.jpg)
Solar Radiation
m
p/ps = fraction of atmosphere above point = 1
• m= 1/(sin()• m = non-dimensionaloptical depth at surface• m =1,
• m =2,
• m =4,
• When sun at 14o , light travelling through 4 atmospheres
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Solar Radiation
M
p/ps = fraction of atmosphere above point
• M = m p/ps = non-dimensional optical depth at pressure p• At 500 mb (p/ps = .5):
•for zenith angle = 14o, equivalent to path length at sea level for zenith angle of 30o
• so, more radiation at higher elevation
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Solar Radiation- Ideal Atmosphere
Pressure (mb) M=1;zenith angle= 90o
M=2; zenith angle= 30o
1000 mb 1233 W/m2 1136 W/m2
500 mb 1288 W/m2 1227 W/m2
Diff = 55 W/m2 91 W/m2
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Solar radiation reduced in lower atmosphere by:
--absorption of radiation by water vapor
-- Mie scattering by aerosols
Barry (1992)
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Absorbed Solar Radiation• Absorbed solar radiation depends strongly
on albedo: Abs Solar = Solar (1 – )• Snow cover reflects solar radiation and diminishes
absorbed solar radiation
• Annually, snow cover at high elevation later in season than in valleys tends to cause absorbed solar radiation to diminish with elevation
Whiteman (2000)
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Incoming Longwave Radiation
Iijima and Shinoda (2002)
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Outgoing Infrared Radiation
• Stefan-Boltzmann Law: IR = T4
• As elevation increases:– temperature decreases, IR radiation decreases– Optical thickness of atmosphere decreases (less
greenhouse gases, including water vapor), atmospheric transparency to outgoing radiation increases, more IR escapes
• Emissivity () of snow and ice is high
Whiteman (2000)
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Infrared Radiation: December, Austrian AlpsAltitude (m) Bare ground
W/m2
Snow cover W/m2
200 289 301
1000 270 287
2000 255 274
3000 240 255
Barry (1992)
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Net Radiation• Net Radiation =
Absorbed solar radiation + downwelling IR – IR
• Effect of altitude on net radiation is variable and depends most strongly on decrease with height of absorbed solar radiation
Barry (1992)
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Peter Sinks
-200
-100
0.00
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-200
-100
0.00
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EXP2
Sept. 11Sept. 10Sept. 9 Sept. 12
QG
QNET
QH
EXP3
12 18 0 06 12 18 0 06 12 18 0 06 12Hour (MDT)
Clements (2000)
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Radiation Budget on Slope
Temperatureslope
Temperature ground
solar
downwelling IR
IR
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Variations in sunrise time
Whiteman (2000)
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Influence of aspect (orientation)
Barry (1992)
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Influence of aspect (orientation)
Barry (1992)
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Influence of slope angle
Barry (1992)
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Inclination angle, valley orientation,
season
South – north West - east
Whiteman (2000)
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Microclimates
• Small topographic irregularities
• Differences in slope angle and aspect
• Types (Turner 1980)• Sunny windward slope (high radiation; high wind)
• Sunny lee slope (high radiation; low wind)
• Shaded windward
• Shaded lee
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Microclimates
Barry (1992)