This page describes the sources of the soils datasets used by the NCA-LDAS land-surface models.

The soil texture for Noah-3.3 is from a global hybrid STATSGO/FAO soil texture map produced by NCAR. This map is a hybrid (30-second for CONUS and 5-min elsewhere) 16-category soil texture map with two soil layers represented. For Noah-3.3 NCA-LDAS, the top soil layer in this dataset is used for the soil texture for all Noah soil layers. The FAO index values are modified to fit the STATSGO index texture values.

Here is more information on the original STATSGO texture class data and index values as well as the original FAO soil map index (see the "Zobler" tab) and related information, including how the FAO global soil dataset used for NCA-LDAS was originally derived.

The STATSGO and FAO indices are set to STATSGO Texture Index Values (16 classes):

 Index   Texture
 -----   -------
   1     SAND
   2     LOAMY SAND
   3     SANDY LOAM
   4     SILT LOAM
   5     SILT
   6     LOAM
   7     SANDY CLAY LOAM
   8     SILTY CLAY LOAM
   9     CLAY LOAM
  10     SANDY CLAY
  11     SILTY CLAY
  12     CLAY
  13     ORGANIC MATERIAL
  14     WATER
  15     BEDROCK
  16     OTHER (land-ice)

The soil moisture/temperature levels for the NCA-LDAS LSMs are:

• Noah-3.3:
  • Field 1: 0.0 - 0.1m (thickness of 10cm)
  • Field 2: 0.1 - 0.4m (thickness of 30cm)
  • Field 3: 0.4 - 1.0m (thickness of 60cm)
  • Field 4: 1.0 - 2.0m (thickness of 100cm)