Albedo libraries are a collection of spectral albedos of different surface types. This option must be used either with surface_type or surface_type_map, in order to select the specific surface type. There are two possibilities for libraries: the built-in IGBP library or a user defined albedo library.

The built-in library of the International Geosphere Biosphere Programme is selected with  

albedo_library IGBP

 
The IGBP library contains 20 surface types which are set by surface_type:  

1 evergreen_needle_forest
2 evergreen_broad_forest
3 deciduous_needle_forest
4 deciduous_broad_forest
5 mixed_forest
6 closed_shrub
7 open_shrubs
8 woody_savanna
9 savanna
10 grassland
11 wetland
12 cropland
13 urban
14 crop_mosaic
15 antarctic_snow
16 desert
17 ocean_water
18 tundra
19 fresh_snow
20 sea_ice

 
Surface types 1 - 17 are defined by the International Geosphere Biosphere Programme (IGBP); additionally there are tundra, fresh_snow, and sea_ice surface types. The spectral albedo of the ground is determined as a function of solar zenith angle, precitable water, and clouds. The spectral resolution equals the grid of the correlated-k Fu/Liou parameterisation. This library originates from the NASA CERES/SARB Surface Properties Project, see Belward1996.

For creating your own albedo library use albedo_library path, where path is the path of the directory where the albedo data is stored. The files are expected to have the names albedo_01.dat, albedo_02.dat, ... If surface_type 1 is specified the albedo from albedo_01.dat will be used, and so on. Each file is required to have two columns: Column 1 is the wavelength in nm, and column 2 the corresponding Lambertian surface albedo. The wavelength grid may be freely set. The albedo will be interpolated linearely to the wavelength grid used for the radiation calculation. Comments start with #. Empty lines are ignored. This option is similar to albedo_file, except that it offers an easy way to use the option surface_type_map in combinition with albedo files.