Changes between Version 30 and Version 31 of DevelopmentActivities/CMIP6/DevelopmentsCMIP6/soil_physic

Timestamp:

2015-02-27T14:56:50+01:00 (9 years ago)

Author:

peylin

Comment:

--

DevelopmentActivities/CMIP6/DevelopmentsCMIP6/soil_physic

@@ -295 +295 @@
 
 
+== Note on soil freezing by Isabelle G. (email exchange with Philippe P) ==
+
+
+Non, je n'ai pas désactivé le gel pour les petites couches. En revanche, j'ai créé une variable qui stocke en mémoire l'énergie libérée au cours du gel, sur l'ensemble du profil. Au moment du dégel, une fois que le sol a complètement dégelé, on compare ce stock d'énergie à l'énergie consommée pour dégeler le sol. Si cette énergie est supérieure à la première, on considère qu'on a trop "fondu" et qu'on aurait dû réchauffer à la place, donc on réajuste la température, sur l'ensemble du profil.
+Ta prochaine question sera sans doute pourquoi j'ai travaillé sur l'ensemble du profil et pas par couches. La réponse est que j'avais la vieille version de la neige, implicite dans le sol. Donc, les "couches de sol" changeaient dans le temps en fonction de la hauteur de neige, donc il était difficile de garder une trace de l'énergie du gel/dégel du sol par couche.
+
+Isabelle
+
+
 = Summary of discretization and snow coupling issues (26 Fev 2015 meeting) =
 
@@ -311 +320 @@
  - new common scheme with 2m for W and 8m for T: V3
 
-First outcomes for T are:
+Some results for T:[[BR]]
+
 5 meters is not enough for diunal/seasonal cycle of T (criterial is that the amplitude of the cycle at lowest layer should lower by a factor "E-3" of that of the first layer ???)
-we need a depth of at least 9.5 m for sand soil when using new USDA texture classes
-
-For soil moisture:
-Differences between V2 and V3 are not too large
-V2 need a longer spin-up (at least 40 yr)
-The impact on the river dischages is significant for some rivers 
-changes in drainage is large but additional graphics are needed to better quantify the changes 
+
+we need a depth of at least 9.5 m for sand soil when using new USDA texture classes.
+
+
+For soil moisture:[[BR]]
+
+Overall the differences between V2 and V3 are not too large for the fluxes ?
+
+V2 need a longer spin-up (at least 40 yr compared to 20 yr for V3). Soil moisture at t0 = 0.2 m3/m3
+ 
+Impact of the drainage is large for JJA, but additional graphics are needed to better quantify the changes
+
+The impact on the river dischages is only significant for some rivers: additional test ?
 
 
 === Discussion ===
 
-With sand and 
+In general the impact of discretization on Temperature is small
+
+The impact of the depth on Water balance seems less important than in ISBA but more checks are needed
+
+We discussed how we should interpret the "W scheme" and the differences between the "Theta" values at the nodes (that are not the center of the layers) and the "water-content" values that are the integral of the water content for a given layer (and that are thus associated to any point). The specific case of the surface layer with the first node at the surface needs to be keep in mind.  
+
+Link between W and T scheme: for the heat capacity we should use the mean water content of the layer; for the conductivity, we should preferably use the water content at the interface. However, any  choice is not that critical given the uncertainty on the physical laws. 
+
+Soil Freezing:
+
+