Opened 3 years ago

Last modified 14 months ago

#416 new enhancement

Foreseen simplifications regarding the soil texture

Reported by: aducharne Owned by: aducharne
Priority: minor Milestone: Not scheduled yet
Component: Physical processes Version: trunc
Keywords: Cc:

Description

In the present version of the code (CMIP6v1), soil texture is defined along two systems:

  • granolumetric composition (or particle size ditribution, PSD) = % of clay/sand/silt particles (related dimension = ntext = 3)
  • texture class, with either 3 textures if we read the Zobler map, or 12 if we read the USDA map (related dimension = nscm)

In many places, there is an amiguity between the three particle sizes (clay/sand/silt) and the three texture classes "of Zobler" (Clay/Sand/Loam?).

Since the 3 texture classes of Zobler are a sample of the 12 USDA classes, I propose the following simplifications:

  • remove the zobler parameters and replace them by a pointer from the 3 Zobler classes to the three corresponding USDA classes (1,2,3) => (3,6,9)
  • change the definition of soil texture by external keywords (if IMPVEG and IMPSOIL = TRUE): presently, the 3-element vector for SOIL_FRACTIONS must contain the areal fraction of the three texture classes "of Zobler" (Clay/Sand/Loam?) in the grid-mesh, and the largest areal fraction defines the dominant texture that is used over the whole domain. It is proposed to replace it by the granulometric composition, so we can force any USDA texture class. In addition, it permit to ensure that the clayfraction is always consistent with the soil texture.

These changes should be implemented when also preparing the model to use alternative soil maps for SP-MIP.

Change History (3)

comment:1 Changed 2 years ago by aducharne

  • Milestone changed from ORCHIDEE 3.0 to ORCHIDEE 4.0

comment:2 Changed 17 months ago by aducharne

Other improvements can also be proposed quite readily:
1) reading soil maps describing the texture based on the particle size ditribution (%clay, %sand, %silt). This is linked to the simplification of IMPSOIL, and would rely on a function that I have widely tested in other contexts;
2) calculate the field capacity and wilting point directly in ORCHIDEE, based on the other soil parameters (useful if you change these paarmeters, espcailly when doing automatic sensitivity tests or optimization)

comment:3 Changed 14 months ago by luyssaert

  • Milestone changed from ORCHIDEE 4.0 to Not scheduled yet
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