ORCHIDEE Development Section

ALBEDO

Default ORCHIDEE configuration for the albedo calculation

The full list of default albedo coefficients for the two wavelength bands (near infrared and visual) and snow-related parameters are presented in the tables below. Note that the snow-related parameters are equal for both near-infrared (NIR) and visible (VIS) ranges. This is because in the default ORCHIDEE configuration no differentiation is done between the ranges in respect to the snow contribution to the albedo calculation.

Albedo coefficients for vegetated, snowed and non-biological surfaces

PFT12345678910111213
 near infrared
\(alb_\mathsf{leaf}\)0.200.220.220.220.220.220.220.220.300.300.300.30
\(alb_\mathsf{snow,aged}\)0.350.140.140.140.140.140.140.180.180.180.18
\(alb_\mathsf{snow,dec}\)0.450.060.060.110.060.110.110.520.520.520.52
\(alb_\mathsf{nobio}\)0.2
 visible
\(alb_\mathsf{leaf}\)0.040.060.060.060.060.060.060.060.100.100.100.10
\(alb_\mathsf{snow,aged}\)0.350.140.140.140.140.140.140.180.180.180.18
\(alb_\mathsf{snow,dec}\)0.450.060.060.110.060.110.110.520.520.520.52
\(alb_\mathsf{nobio}\)0.6

Parameters involved in snow calculations

ParameterValue
\(d_\mathsf{snow,cri}\), m0.1
\(\rho_\mathsf{snow,cri}\), kg/m3330
\(tcst_\mathsf{snow}\), days5
\(age_\mathsf{snow,max}\), days50
\(trans_\mathsf{snow}\), m0.3

In the default ORCHIDEE configuration the bare soil albedo (\(alb_\mathsf{bs}\), also called background albedo) is determined for each grid cell depending on the soil color type, taken from the Henderson-Sellers and Wilson dataset. The albedo coefficients assigned to each of the 9 soil color types are given in the table below.

Albedo coefficients for different soil color types

Soil color123456789
\(alb_\mathsf{bg,VIS}\)0.180.160.160.150.120.1050.090.0750.25
\(alb_\mathsf{bg,NIR}\)0.360.340.340.330.300.250.200.150.45