Changes between Version 112 and Version 113 of Documentation/TrunkFunctionality4

Timestamp:

2021-11-18T16:37:10+01:00 (2 years ago)

Author:

luyssaert

Comment:

--

Documentation/TrunkFunctionality4

@@ -112 +112 @@
 
 === Albedo (background) ===
-Describes r6614. If covered by snow, the background albedo is calculated in the VIS and NIR wavelengths by the snow module and accounts for snow age and snow density. If not covered by snow, the background albedo is not simulated but prescribed by the parameters '''bgd_reflectance(:,ivis)''' and '''bgd_reflectance(:,inir)'''. If the background is partly covered by snow, the snow albedo and the background albedo are merged, which allows snow to settle under the canopy, reflecting In deciduous forest, grasslands and croplands, the background albedo is known to be strongly affected by the phenology and senescence of the understory vegetation. ORCHIDEE trunk has two options to prescribe the background albedo:
+Describes r7253. If covered by snow, the background albedo is calculated in the VIS and NIR wavelengths by the snow module and accounts for snow age and snow density. If not covered by snow, the background albedo is not simulated but prescribed by the parameters '''bgd_reflectance(:,ivis)''' and '''bgd_reflectance(:,inir)'''. If the background is partly covered by snow, the snow albedo and the background albedo are merged, which allows snow to settle under the canopy. In deciduous forest, grasslands and croplands, the background albedo is known to be strongly affected by the phenology and senescence of the understory vegetation. 
+
+ORCHIDEE trunk has three options to calculate the background albedo for the bare soil (PFT1):
+* It can read the soil color (set alb_bg_model = y and alb_bg_modis = n) and account for soil moisture
+* It can read the soil color (set alb_bg_model = n and alb_bg_modis = n) and ignore soil moisture
+* It can read the MODIS background albedo (alb_bg_modis = y , value of alb_bg_model doesn't matter). This option also ignores the soil moisture.
+
+ORCHIDEE trunk has two options to calculate the background albedo for vegetated pixels:
 * The background albedo is prescribed per PFT but is constant throughout the year. This option has been evaluated over Europe. Set '''alb_bg_modis''' = n.
 * The background albedo is constant across PFTs. This option reads background maps. Given that those maps are based on the JRC TIP product, they should be compatible with the new albedo scheme. This option, however, has not been evaluated yet. Set '''alb_bg_modis''' = y.
+
+When alb_bg_modis = y this is the option used to calculate the background albedo for PFT1 and vegetated PFTs.