Changes between Version 26 and Version 27 of DevelopmentActivities/CMIP6/DevelopmentsCMIP6/soil_physic

Timestamp:

2015-02-27T14:03:19+01:00 (9 years ago)

Author:

peylin

Comment:

--

DevelopmentActivities/CMIP6/DevelopmentsCMIP6/soil_physic

@@ -311 +311 @@
 The objective is to propose a scheme flexible enough to allow users to test different configurations depending on their objectives and to be able to account for deep soil thermic representation in the case of permafrost.
 
-Scheme: [https://forge.ipsl.jussieu.fr/orchidee/attachment/wiki/Meetings/CMIP6/Physic/soil_discretization.ppt][[BR]]
+Scheme: [https://forge.ipsl.jussieu.fr/orchidee/attachment/wiki/Meetings/CMIP6/Physic/soil_discretization.pptx][[BR]]
+
+The main principle are:
+ -- The T scheme is always as depth or deeper than the W scheme
+ -- W and T share the same common discretization for the common part: the layers are the same; For the nodes:  W has the firt node at the surface while T has it at the middle of the first layer; Else they have the same node position
+ -- The upper part of the scheme follow a geometric discretization of reason 2 (like the current W scheme)
+ -- Below a certain depth, depth_lin, we have for the W and T a linear discretization, with the depth of each layers equal to that of the lowest layer of the "geometrical part" of the scheme. Note that depth_lin may be equal to depth max with thus no linear discretization section.
+ -- Below another depth, depth_geom, we have again the geometrical discretization with a reason xx to be defined. This allows to model a deep soil for permafrost modelling. Note that Depth_geom may also be equal to depth_max with thus no bottom geometrical discretization.
+
+The list of parameters to define the scheme would be:
+ -- depth_max : maximum soil depth for W and T
+ -- depth_lin : depth below which linear discretization occurs
+ -- depth_geom : depth below which geometrical discretization occurs again 
+ -- reason_geom_up: equal currently to 2 (but we could possibly change it)
+ -- reason_geom_below: we should decide what is the best following the test for permafrost
+ -- depth_Wmax : max depth of the W discretization, between [depth_lin, depth_geom]
+
+Modulation of the Thermal properties as a function of the Water content:
+ -- Heat capacity of each layer (C) should be a function of the layer water content: thus a function of the layer total water content ("W" variable of CWRR divided by the layer depth)
+ -- Conductivity between layers (Lambda) should be a function of the "Theta" of layer i and i+1 (weighted arythmetic mean using the depth of layers)
+ -- For the part of the thermal scheme that is below the hydrology scheme: we should take a constant in time value of "Theta" and "water content", to avoid changing heat capacity over time and thus not conserving the energy (without any corresponding imput/output of energy by water flow); the values to choose is open for discussion/tests ?
+   
+
+== Snow coupling ==
+
+- Presentation by Fuxing of his work on the soil W and T discretization: [https://forge.ipsl.jussieu.fr/orchidee/attachment/wiki/Meetings/CMIP6/Physic/Orchidee_snow_CMIP6.pdf​​][[BR]]
 
  
 
-== Snow coupling ==
-
-- Presentation by Fuxing of his work on the soil W and T discretization: [https://forge.ipsl.jussieu.fr/orchidee/attachment/wiki/Meetings/CMIP6/Physic/Orchidee_snow_CMIP6.pdf​​][[BR]]
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