Available Energy: Net Radiation and Soil Heat Flux - Transport in the Atmosphere-Vegetation-Soil Continuum - page 34

0.25

0.2

0.15

0.1

0.05

0.0

0.01 0.1 1.0 10.0

Roughness length(m)

Figure 2.11 Relationship between albedo and aerodynamic roughness (see Chap-
ter 3 ) for vegetated surfaces from a global database. (Data from Hagemann, 2002 )

Table 2.1 Typical values for shortwave albedo (hemispheric, broadband) and
longwave emissivity for different surface types

Surface type Remark R ε s

Ocean High sun 0.05 0.95

Low sun 0.1-0.5 0.95

Forest Tropical rain forest 0.07-0.15 0.98

Coniferous 0.1-0.19 0.98

Deciduous 0.14-0.2 0.96

Crops 0.15-0.25 0.96

Grasses 0.15-0.30 0.96

Soils Dark, wet 0.1

Wet sandy 0.1-0.25 0.98

Dry sandy 0.2-0.4 0.95

Wet clay 0.1-0.2 0.97

Dry clay 0.2-0.35 0.95

Snow Fresh 0.65-0.95 0.95

Old 0.45-0.65 0.9

Urban areas 0.10-0.27 0.85-0.96

From Garratt ( 1992 ) and after Oke ( 1987 ).