ALBEDO

3-STEP ALBEDO OPTIMIZATION

ORCHIDEE simulation configuration :

  • Model : ORCHIDEE 2.2
  • Forcing : CRUJRA v2 (0.5°)
  • PFT maps : ESA CCI LC (1992-2018) aggregated to 0.25° with the old CWT "ESA -> Generic" and the new CWT "Generic -> ORCHIDEE"
  • Period : 1992-2018 (with 10Y-spinup using fixed PFT map for 1992)
  • Used in optimization : 12 monthly maps averaged for 2009-2018

STEP 1 : LEAF ALBEDO OPTIMIZATION

Data points (month-pixels) selection :
  • MODIS is valid (not masked)
  • ORCHIDEE is valid (not masked)
  • Snow fraction = 0
  • Continental fraction > 0.99
  • Inland water fraction < 0.2
The graph below shows the number of data points (months) selected at each grid cell (from 0 to 12) :

Optimization method : L-BFGS-B with 14 optimized parameters, gradient calculation using analytical derivative

LEAF_ALB_NIRPFT2PFT3PFT4PFT5PFT6PFT7PFT8PFT9PFT10PFT11PFT12PFT13PFT14PFT15
prior0.230.180.180.20.240.150.260.20.240.270.280.260.240.24
min0.10.10.10.10.10.10.10.10.10.10.10.10.10.1
max0.30.30.30.30.30.30.30.30.40.40.40.40.40.4
post0.2050.1860.150.1760.2350.1290.2710.1860.290.2610.2590.2890.2320.311
LEAF_ALB_VISPFT2PFT3PFT4PFT5PFT6PFT7PFT8PFT9PFT10PFT11PFT12PFT13PFT14PFT15
prior0.040.040.040.040.030.030.030.030.060.060.060.060.060.06
min0.010.010.010.010.010.010.010.010.010.010.010.010.010.01
max0.050.050.050.050.050.050.050.050.10.10.10.10.10.1
post0.02220.02960.02960.02340.01520.03040.02970.010.04650.03130.05240.06080.010.0217


STEP 2 : SNOW ALBEDO OPTIMIZATION

Data points (month-pixels) selection :
  • MODIS is valid (not masked)
  • ORCHIDEE is valid (not masked)
  • Snow fraction > 0
  • Continental fraction > 0.99
  • Inland water fraction < 0.2
The graph below shows the number of data points (months) selected at each grid cell (from 0 to 12) :

Optimization method : L-BFGS-B with 24 optimized parameters, gradient calculation using finite differences approach

SNOW_ALB_NIRPFT1PFT2PFT3PFT4PFT5PFT6PFT7PFT8PFT9PFT10PFT11PFT12PFT13PFT14PFT15
snowa_aged_prior0.5000.10.370.080.160.170.270.440.440.440.4400.44
snowa_dec_prior0.13000.10.10.160.040.070.080.120.120.120.1200.12
min(aged+dec)0.05000.050.050.050.050.050.050.050.050.050.0500.05
max(aged+dec)0.95000.950.950.950.950.950.950.950.950.950.9500.95
min(aged/(aged+dec))0.05000.050.050.050.050.050.050.050.050.050.0500.05
max(aged/(aged+dec))0.95000.950.950.950.950.950.950.950.950.950.9500.95
snowa_aged_post0.385000.2030.9020.1330.1750.4380.2590.6360.6980.5360.61500.579
snowa_dec_post0.163000.01070.04750.006990.00920.02310.01360.03350.03680.02820.032400.0305
SNOW_ALB_VISPFT1PFT2PFT3PFT4PFT5PFT6PFT7PFT8PFT9PFT10PFT11PFT12PFT13PFT14PFT15
snowa_aged_prior0.74000.080.240.070.180.180.330.570.570.570.5700.57
snowa_dec_prior0.21000.140.080.170.050.060.090.150.150.150.1500.15
min(aged+dec)0.05000.050.050.050.050.050.050.050.050.050.0500.05
max(aged+dec)0.95000.950.950.950.950.950.950.950.950.950.9500.95
min(aged/(aged+dec))0.05000.050.050.050.050.050.050.050.050.050.0500.05
max(aged/(aged+dec))0.95000.950.950.950.950.950.950.950.950.950.9500.95
snowa_aged_post0.633000.06850.9020.009590.1090.6270.2970.9020.9020.7420.7700.862
snowa_dec_post0.234000.00360.04750.04040.005750.0330.01560.04750.04750.0390.040500.0454


STEP 3 : BACKGROUND ALBEDO OPTIMIZATION

Data points (month-pixels) selection :
  • MODIS is valid (not masked)
  • ORCHIDEE is valid (not masked)
  • Total_bare_soil * (1 - snow_fraction) > 0.5
The graph below shows the number of data points (months) selected at each grid cell (from 0 to 12) :

Optimization method : L-BFGS-B with 1 optimized parameter individually at each grid cell
  • Prior : JRC TIP product
  • Range of variation : ±0.1

RESULTS (seasonal cycle across different regional masks)