Changes between Version 21 and Version 22 of Documentation/CouplingLMDZ

Timestamp:

2014-10-29T00:11:32+01:00 (10 years ago)

Author:

peylin

Comment:

--

Documentation/CouplingLMDZ

@@ -17 +17 @@
  8. Brusaert (2005). Hydrology, p124-135: [http:"//forge.ipsl.jussieu.fr/orchidee/attachment/wiki/Documentation/CouplingLMDZ/brutsaert2005_p124-135.pdf" "Brutsaert 2005"]
 [[BR]]
+
 = EVAPO-TRANSPIRATION =
 
@@ -76 +77 @@
 In order to save computing time, the time step of the radiation code is longer than that of the other components of the model (rest of the atmospheric physics and call to LSM). If the radiation budget of each component is updated at a shorter time step, the energy is not conserved. This is the case in the ORCHIDEE.trunk version where the LWnet (through lwup) is calculated separately in LMDZ and ORCHIDEE. 
 
-Note that the same is true for the SWnet. To ensure energy conservation, SWnet should be constant between two calls of the RT model of LMDZ. This implies that the surface albedo does not vary between these two calls.
+Note that the same is true for the SWnet. To ensure energy conservation, SWnet should be constant between two calls of the RT model of LMDZ. This implies that the surface albedo does not vary between these two calls. However, currently, the '''net SW''' flux computed by LMDZ is used by ORCHIDEE for the surface energy budget. The albedo computed by ORCHIDEE is used by LMDZ when radiation is computed (LMDZ uses the instantaneous value of the albedo, albedo change is of second order compared to other changes, in particular clouds). THUS, currently '''in a coupled mode the albedo computed by ORCHIDEE is not used by ORCHIDEE to update the net SW flux used in the surface energy budget equation''' therefore the energy is conserved.
+
 
 An option which favors the energy conservation has been introduced by Fuxing and Jean-Louis: Practically the LWup is updated only when the radiative code is called.