NLDAS Soils Information

Updated (25 Apr 2014): Soil parameter values specifically used for the Mosaic and Noah LSMs - and a link to the parameters used for the VIC LSM - are provided below.

The soils datasets featured on this page were derived from 1-km Penn State STATSGO data and have 11 layers and 16 texture classes. Outside of the United States, 5-minute ARS FAO data is used instead. Many thanks to Qingyun Duan of the NOAA Office of Hydrology for providing the STATSGO datasets for NLDAS.

The soil datasets layers are:
Layer Thickness Depth to Top Depth to Bottom
1 5 cm (2 in) 0 cm (0 in) 5 cm (2 in)
2 5 cm (2 in) 5 cm (2 in) 10 cm (4 in)
3 10 cm (4 in) 10 cm (4 in) 20 cm (8 in)
4 10 cm (4 in) 20 cm (8 in) 30 cm (12 in)
5 10 cm (4 in) 30 cm (12 in) 40 cm (16 in)
6 20 cm (8 in) 40 cm (16 in) 60 cm (24 in)
7 20 cm (8 in) 60 cm (24 in) 80 cm (31 in)
8 20 cm (8 in) 80 cm (31 in) 100 cm (39 in)
9 50 cm (20 in) 100 cm (39 in) 150 cm (59 in)
10 50 cm (20 in) 150 cm (59 in) 200 cm (79 in)
11 50 cm (20 in) 200 cm (79 in) 250 cm (98 in)
The soil datasets texture classification definitions are:
1 S Sand
2 LS Loamy sand
3 SL Sandy loam
4 SIL Silt loam
5 SI Silt
6 L Loam
7 SCL Sandy clay loam
8 SICL Silty clay loam
9 CL Clay loam
10 SC Sandy clay
11 SIC Silty clay
12 C Clay
13 OM Organic materials
14 W Water
15 BR Bedrock
16 O Other

NLDAS Soil Texture Classes Illustrations

First most predominant soil texture classes over 1/8th-degree NLDAS domain. Classes 1 to 7 are most common over the domain, with classes 8 and higher sometimes located over the central areas.
First Most Predominant Surface Soil Classes Over NLDAS Domain

First most predominant soil texture classes over 1/8th-degree NLDAS domain. Classes 1 to 7 are most common over the domain, with classes 8 and higher sometimes located over the central areas.
First Most Predominant Surface Soil Classes Over NLDAS Domain - same map as above but using index numbers instead of descriptive soil classes

Second most predominant soil texture classes over 1/8th-degree NLDAS domain. Classes 1 to 7 are most common over the domain, with classes 8 and higher sometimes located over the central and southern areas. Many areas are blank as they have no 2nd most predominant soil class.
Second Most Predominant Surface Soil Classes Over NLDAS Domain

NLDAS Soil Texture Dataset (Binary)

The following dataset is the exact same as the first most predominant surface soil classes illustration shown above.

NLDAS Soil Texture Datasets (ASCII)


Information on First Most Predominant Surface Soil Texture Classes:
The following soil texture file contains the first most predominant soil texture class of each soil layer. The files consist of 1 soil texture value per 1/8th-degree grid box with gridpoint (1,1) located at the upper left of the NLDAS grid. The files can be read with the following statement:

      read(10,40) ((isoil(i,j),i=1,464),j=1,224)
40    format(464i3))

Information on First and Second Most Predominant Surface Soil Texture Classes:
The following 2 soil texture files indicate the percentage of each 1/8th-degree surface layer grid box that is taken up by the first most predominant and second most predominant soil texture classes. The files consist of 1 percentage value per 1/8th-degree grid box with gridpoint (1,1) located at the upper left of the NLDAS grid. The files can be read with the following statement:

      read(10,40) ((pcnt(i,j),i=1,464),j=1,224)
40    format(464f5.0)

Detailed Information on All 11 Soil Layers:
The following 11 soil texture files contain data in the following format:

Column 1 X Coordinate Index
Column 2 Y Coordinate Index
Column 3 Longitude (center of 1/8th-degree grid boxes)
Column 4 Latitude (center of 1/8th-degree grid boxes)
Columns 5-21 Number of Occurrences of Soil Classes 1-16 in Each 1/8th-Grid Box

They can be read with the following statement, with gridpoint (1,1) located near the upper left of the NLDAS grid at 49.3125 North:

      read(20,100) ix,iy,xlon,ylat,(iclass(j),j=1,16)
100   format (2i4,1x,f9.4,f8.4,20i4)
  • Layer 1 Data (stex_tab.01)
  • Layer 3 Data (stex_tab.03)
  • Layer 5 Data (stex_tab.05)
  • Layer 7 Data (stex_tab.07)
  • Layer 9 Data (stex_tab.09)
  • Layer 11 Data (stex_tab.11)
  • Layer 2 Data (stex_tab.02)
  • Layer 4 Data (stex_tab.04)
  • Layer 6 Data (stex_tab.06)
  • Layer 8 Data (stex_tab.08)
  • Layer 10 Data (stex_tab.10)
  • The following 11 soil texture files contain data in the following format:


    (Excluding Bedrock, Ocean and Missing Points) in each 1/8th-Degree Pixel
    Column 1 X Coordinate Index
    Column 2 Y Coordinate Index
    Column 3 Longitude (center of 1/8th-degree grid boxes)
    Column 4 Latitude (center of 1/8th-degree grid boxes)
    Column 5 Number of Inland Water Points in Each 1/8th-Degree Pixel
    Column 6 Number of Bedrock Points in Each 1/8th-Degree Pixel
    Column 7 Number of Missing or Ocean Points in Each 1/8th-Degree Pixel
    Column 8 Number of Soil Classifications
    Columns 9-10 The First Most Dominant Classification and the Corresponding Number of Occurences in Each 1/8th-Degree Pixel
    Columns 11-12 The Second Most Dominant Classification and the Corresponding Number of Occurences in Each 1/8th-Degree Pixel

    They can be read with the following statement, with gridpoint (1,1) located near the upper left of the NLDAS grid at 49.3125 North:

          read(10,200) ix,iy,xlon,ylat,nwat,nroc,nmis,ncl,
         +           (icl(j),mcl(j),j=ncl,1,-1)
    200   format(2i4,1x,f9.4,f8.4,20i4)
    
  • Layer 1 Data (SOILTEXT.01)
  • Layer 3 Data (SOILTEXT.03)
  • Layer 5 Data (SOILTEXT.05)
  • Layer 7 Data (SOILTEXT.07)
  • Layer 9 Data (SOILTEXT.09)
  • Layer 11 Data (SOILTEXT.11)
  • Layer 2 Data (SOILTEXT.02)
  • Layer 4 Data (SOILTEXT.04)
  • Layer 6 Data (SOILTEXT.06)
  • Layer 8 Data (SOILTEXT.08)
  • Layer 10 Data (SOILTEXT.10)
  • NLDAS Soil Hydraulic Properties Datasets (ASCII)

    The following soil hydraulic property files contain data in the following format:

    Column 1 X Coordinate Index
    Column 2 Y Coordinate Index
    Column 3 Longitude (center of 1/8th-degree grid boxes)
    Column 4 Latitude (center of 1/8th-degree grid boxes)
    Column 5 Porosity (fraction)
    Column 6 Field Capacity (fraction)
    Column 7 Wilting Point (fraction)
    Column 8 B Parameter
    Column 9 Saturated Soil Matric Potential (in m of H2O)
    Column 10 Saturated Soil Hydraulic Conductivity (in m/s)
    Column 11 Unknown

    The files can be read with the following statement, with gridpoint (1,1) located at the upper left of the NLDAS grid:

          read(20,200) ic,ir,xlon,ylat,xporos,xfldcp,xwltpt,
         x                     xb,xpsi50,xks50
    200   format(2i4,1x,f9.4,f8.4,5f9.3,e11.3)
    

    The NLDAS LSMs primarily used the first dataset listed below (based on Cosby's numbers except Ksat, which is based on Rawls's); the other datasets are provided for informational purposes only. However, LSM-specific soil parameter values may have been used instead; please check below.

    Soil hydraulic properties dataset based on Cosby's numbers except Ksat, which is based on Rawls's work:
  • Layer 1 Data (COS_RAWL.01)
  • Layer 3 Data (COS_RAWL.03)
  • Layer 5 Data (COS_RAWL.05)
  • Layer 7 Data (COS_RAWL.07)
  • Layer 9 Data (COS_RAWL.09)
  • Layer 11 Data (COS_RAWL.11)
  • Layer 2 Data (COS_RAWL.02)
  • Layer 4 Data (COS_RAWL.04)
  • Layer 6 Data (COS_RAWL.06)
  • Layer 8 Data (COS_RAWL.08)
  • Layer 10 Data (COS_RAWL.10)
  • Soil hydraulic properties dataset based on Clapp and Hornberger (1978) - WRR:

  • Layer 1 Data (HYD_CLAP.01)
  • Layer 3 Data (HYD_CLAP.03)
  • Layer 5 Data (HYD_CLAP.05)
  • Layer 7 Data (HYD_CLAP.07)
  • Layer 9 Data (HYD_CLAP.09)
  • Layer 11 Data (HYD_CLAP.11)
  • Layer 2 Data (HYD_CLAP.02)
  • Layer 4 Data (HYD_CLAP.04)
  • Layer 6 Data (HYD_CLAP.06)
  • Layer 8 Data (HYD_CLAP.08)
  • Layer 10 Data (HYD_CLAP.10)
  • Soil hydraulic properties dataset based on Cosby et al. (1984) - WRR:
  • Layer 1 Data (HYD_COSB.01)
  • Layer 3 Data (HYD_COSB.03)
  • Layer 5 Data (HYD_COSB.05)
  • Layer 7 Data (HYD_COSB.07)
  • Layer 9 Data (HYD_COSB.09)
  • Layer 11 Data (HYD_COSB.11)
  • Layer 2 Data (HYD_COSB.02)
  • Layer 4 Data (HYD_COSB.04)
  • Layer 6 Data (HYD_COSB.06)
  • Layer 8 Data (HYD_COSB.08)
  • Layer 10 Data (HYD_COSB.10)
  • Soil hydraulic properties dataset based on Rawls and Brakensiek (1991) - Advances in Soil Science:
  • Layer 1 Data (HYD_RAWL.01)
  • Layer 3 Data (HYD_RAWL.03)
  • Layer 5 Data (HYD_RAWL.05)
  • Layer 7 Data (HYD_RAWL.07)
  • Layer 9 Data (HYD_RAWL.09)
  • Layer 11 Data (HYD_RAWL.11)
  • Layer 2 Data (HYD_RAWL.02)
  • Layer 4 Data (HYD_RAWL.04)
  • Layer 6 Data (HYD_RAWL.06)
  • Layer 8 Data (HYD_RAWL.08)
  • Layer 10 Data (HYD_RAWL.10)
  • Reference: Rawls, W.J., and D.L. Brakensiek (1991), Estimating soil water retention from soil physical properties and characteristics. In: Advances in Soil Science, Vol. 16, B.A. Stewart, Editor, Springer-Verlag Inc., New York.


    NLDAS Land-Surface Model-specific Information

    Additional details about LSM-specific soil parameters can be found in Paragraph 10 on Page 3 of Mitchell et al. (2004) as well as in Section 5.1 starting on Page 13 of Robock et al. (2003).

    NLDAS Mosaic Soil Hydraulic Properties Dataset

    The Mosaic LSM was configured for NLDAS to have 3 soil moisture layers with thicknesses (from top) of 10cm, 30cm, and 160cm - for a total soil column depth of 2 meters. All 3 soil layers use the same soil texture (predominant surface soil classes shown above) and thus use the same soil parameter values for all layers as well. The one exception is the soil porosity in Mosaic, which is calculated for each of the 3 layers based on a weighted average from the above 11-layer soil textures. The field capacity is not directly used in Mosaic, but is provided below for all three soil layers, based on Equation 20 in Mocko and Sud (1998). The wilting point in Mosaic is a function of both the vegetation type and the soil type. Because Mosaic is run with vegetation tiling (multiple vegetation tiles within a single NLDAS grid box), the weighted average of the wilting point for all vegetation types within the grid box is provided. A lookup table and calculations based on soil texture class(es) are used in the Mosaic code, but maps of the NLDAS Mosaic LSM soil parameter values are provided below:

    NLDAS Noah Soil Hydraulic Properties Dataset

    The Noah LSM was configured for NLDAS to have 4 soil moisture layers with thicknesses (from top) of 10cm, 30cm, 60cm, and 100cm - for a total soil column depth of 2 meters. All 4 soil layers use the same soil texture (predominant surface soil classes shown above) and thus use the same soil parameter values for all layers as well. A lookup table and calculations based on soil texture class are used in the Noah code, but maps of the NLDAS Noah LSM soil parameter values are provided below:

    NLDAS VIC Soil Hydraulic Properties Datasets

    Soil parameter information specific for the NLDAS version of the VIC LSM is available from the Princeton NLDAS parameter page.

    NLDAS SAC Soil Hydraulic Properties Datasets

    Soil parameter information specific for the NLDAS version of the SAC LSM will appear here shortly.