Soil porosity

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GES DISC - jimacker
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Soil porosity

by GES DISC - jimacker » Thu Mar 05, 2020 2:58 pm America/New_York

The GES DISC Help Desk recently received this question from a user, and it was answered by a GES DISC staff scientist. It is provided here for information content.

I have a question regarding the conversion of the soil moisture content from kg m-2 (or mm) to volumetric soil moisture. Therefore, I'll need to know the soil porosity in different grids and I was wondering if such data is available at all in the GLDAS as I couldn't find it.

I have downloaded the soil moisture content data (SoilMoi0_10cm_inst, SoilMoi10_40cm_inst, SoilMoi40_100cm_inst, and SoilMoi100_200cm_inst variables from GLDAS Noah Land Surface Model L4 monthly 0.25 x 0.25 degree V2.0) and one of the downloaded netCDF files is attached for your consideration. Do you have any idea on how to convert these variables in volumetric soil moisture values? Can I get the soil porosity from GLDAS dataset as well or I need to look for it from a different source such as Harmonized World Soil Database (version 1.0) (FAO/IIASA/ISRIC/ISSCAS/JRC 2008) which is used in the ESA CCI soil moisture dataset?

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GES DISC - jimacker
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Re: Soil porosity

by GES DISC - jimacker » Thu Mar 05, 2020 3:00 pm America/New_York

Here is the answer from a GES DISC staff scientist.

In regard to your question on the soil moisture unit conversion, please go to https://ldas.gsfc.nasa.gov/faq/ldas and click on “Q. How can I obtain volumetric soil moisture [m^3 m-3] from the LDAS data?”.

For the GLDAS soil porosity data, please go to https://ldas.gsfc.nasa.gov/gldas/soils. You should be able to find the GLDAS Soil Porosity data in 0.25 degree and 1 degree in NetCDF and binary format.

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Re: Soil porosity

by hh8em » Thu Apr 15, 2021 11:27 am America/New_York

Hi!

I am also having a similar question regarding soil porosity data. I found the global porosity map for 0-2cm layer from the link https://ldas.gsfc.nasa.gov/gldas/soil. However, I did not figure out where to download maps for deep soil layer (e.g. 2-150 cm). Could you please provide some tips on it? Thank you very much for your help!

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Re: Soil porosity

by GES DISC - jimacker » Fri Apr 16, 2021 3:54 pm America/New_York

This answer was provided by a GLDAS subject matter expert at Goddard Space Flight Center.


The Global Land Data Assimilation System (GLDAS) does not use different parameters for “deep” (2-150cm) soil porosity. It only uses the one porosity map for all layers, shown on the LDAS website with an image and netCDF data files.

If a researcher wants to use soil porosity for a different purpose
(not with the GLDAS data), then they can get data and documentation
from this link:
https://ral.ucar.edu/solutions/products ... oah-mp-lsm

which includes

• Hybrid STATSGO/FAO (30-second for CONUS /5-minute elsewhere) Soil Texture
o readme file
o Soil categories/textures
o view graphics [topsoil] [bottom soil]
o download data [topsoil] [bottom soil]
o program

The README file defines the top and bottom soil layers, and there’s
a sample program to read the data, definition of the textures, etc.
Then the user can use this soil texture index map with SOILPARM:

Soil Parameters -- SOILPARM.TBL
-- (documentation)

Please reply if you have additional questions. Note that some of the text shown above will have active Web links on the linked Web page.

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