readme.txt 4/5/04 DESCRIPTION: A GLOBAL DATA SET OF SOIL PARTICLE SIZE PROPERTIES CITATION: ---------- Webb, R. W., C. E. Rosenzweig, and E. R. Levine. 2000. Global Soil Texture and Derived Water-Holding Capacities (Webb et al.). Data set. Available on-line [http://www.daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. COMMENTS: --------- This data set was orignially offered as several ASCII files with data arranged in long columns. Original files include: contizob.ler - contains 2 columns of data including continent code and Zobler soil type (106); soildata.new - contains 4 columns of data including profile depth, percent sand, percent silt, and percent clay; globsoil.dep - soil profile thickness (cm) ASCII array; globsoil.all - potential storage of water in the soil profile (cm) ASCII array; globsoil.roo - potential storage of water in the root zone (mm) ASCII array; globsoil.tex - potential storage of water derived from soil texture (mm) ASCII array; giss2h2o.map - water-holding capacity used in the GISS general circulation model (Model II) (mm) ASCII array; and soilasci.for - FORTRAN code and notes that accompanied the original data files. These files are available with the original documentation in a compressed tar archive in our data pool: http://daac.ornl.gov/daacdata/global_soil/WebbRosenzweig/comp/original_format.tar.gz or you may request them directly from user services at : uso@daac.ornl.gov. At the request of our user community, we have reformatted these data to be read more easily into a Geographic Information System (GIS). Please read below for a listing of files and their descriptions, and please see readme2.txt for more information and a brief description of how these files were created. FILES: ------ COMPANION FILES IN /comp: ------------------------ readme.txt - this file readme2.txt - additional documentation, describing GIS formats in more detail original_format.tar.gz - archive of original documentation and data files zcontinent.txt - a listing/key of the FAO/UNESCO continent codes referenced in this data zobler_106.txt - a listing/key of the Zobler soil types referenced in this data DATA FILES IN /data: -------------------- 1. cont_code.asc - GRID ASCII file containing FAO continent codes (2-10); please see zcontinent.txt in the /comp directory for the continent code key. These values correspond to the volume numbers of the nine major continental divisions in the FAO/UNESCO Soil Map of the World Vols. 2-10 (1971-1981). 2. zobler106.asc - GRID ASCII file containing Zobler soil types (106); please see zobler_106.txt in the /comp directory for the soil type key. These values correspond to the sequence number of the soil types in Zobler's (1986) World Soil Data File. 3. new_soildata.csv - a comma delimited ASCII file that contains the depth, sand, silt, and clay data for each major continent (10), soil type (106), and soil horizon (15). The sand, silt and clay data are stored as proportional values for each soil horizon. Please note that the arbitrary particle size distribution summing to 100% included for Histosols (entries 61-63) should not be used. Instead, values reflecting the physical properties of organic soils and appropriate for specific research objectives should be inserted. The depth data are scaled in meters with the first value being 0m depth for each soil type and the subsequent values the contact depths of contiguous horizons. By definition, the depth variable contains one extra value corresponding to the bottom depth of the lowest horizon for each soil type. Within this data set no soil type had more than 14 soil horizons. In cases when the number of horizons in a soil type was less than 14, a value of -1.0 was used to flag the end of the record for each soil type. For example, a soil type with 10 horizons has 10 data entries in the sand, silt, and clay variables, and 11 data entries in the depth variable. Records 11-15 in this example would be populated with -1.0 (except for the depth variable which would be populated with -1.0 for records 12-15.) Each record has the following attributes: Zobler soil type [ztype] (106), continent code [cont] (10), profile number [profile] (15), contact depth of profile [depth], %sand [sand], %silt [silt], and %clay [clay]. Please note that the individual horizons for each soil type are from the Morphological, Chemical, and Physical Properties Appendix in each of the nine volumes of the FAO/UNESCO Soil Map of the World (1971-1981). Note: the following 15 gzipped export files include the same information as new_soildata.csv in a format that is easily imported into ARC/INFO GIS software. 4. profile1m.e00.gz - ESRI export file, global map of depth, sand, silt, and clay for soil horizon 1. 5. profile2m.e00.gz - ESRI export file, global map of depth, sand, silt, and clay for soil horizon 2. 6. profile3m.e00.gz - ESRI export file, global map of depth, sand, silt, and clay for soil horizon 3. 7. profile4m.e00.gz - ESRI export file, global map of depth, sand silt, and clay for soil horizon 4. 8. profile5m.e00.gz - "" for soil horizon 5. 9. profile6m.e00.gz - "" for soil horizon 6. 10.profile7m.e00.gz - "" for soil horizon 7. 11.profile8m.e00.gz - "" for soil horizon 8. 12.profile9m.e00.gz - "" for soil horizon 9. 13.profile10m.e00.gz - "" for soil horizon 10. 14.profile11m.e00.gz - "" for soil horizon 11. 15.profile12m.e00.gz - "" for soil horizon 12. 16.profile13m.e00.gz - "" for soil horizon 13. 17.profile14m.e00.gz - "" for soil horizon 14. 18.profile15m.e00.gz - "" for soil horizon 15. 19.wrmodelii.asc - GRID ASCII file, global map used to prescribe water-holding capacity (mm) in the GISS general circulation model (Model II) (derived data set - was originally included as a companion file). 20.wrprof.asc - GRID ASCII file, global map of potential storage of water in the soil profile (mm) (derived data set - wwas originally included as a companion file). 21.wrroot.asc - GRID ASCII file, global map of the potential storage of water in the root zone (mm) (derived data set - was originally included as a companion file). 22.wrtext.asc - GRID ASCII file, global map of potential storage of water derived from soil texture (mm) (derived data set - was originally included as a companion file). GIS FORMATS: ------------------------------------------------------------------------- 1. GRID ASCII - a single ASCII array with integer values. (Coordinates listed below are in decimal degrees.) The ASCII file consists of header information containing a set of keywords, followed by cell values in row-major order. The file format is {NODATA_VALUE xxx} row 1 row 2 . . . row n where xxx is a number and the keyword NODATA_VALUE is optional and defaults to -9999. Row 1 of the data is at the top of the grid, row 2 is just under row 1, and so on. The end of each row of data from the grid is terminated with a carriage return in the file. First six lines of file (header): ncols 360 nrows 180 xllcorner -180 yllcorner -90 cellsize 1 NODATA_value -9999 To import this file into ArcInfo, use the following command at an ARC prompt: ASCIIGRID {INT | FLOAT} Arguments - the ASCII file to be converted. - the user specified name of the grid to be created. {INT | FLOAT} - the data type of the output grid. INT - an integer grid will be created. FLOAT - a floating-point grid will be created. Note: This data can also be imported into ArcView (with Spatial Analyst) and ArcGis as ASCII Raster data. 2. ESRI EXPORT FILE - this data can be imported into ARC/INFO GRID using the following command at an ARC prompt: IMPORT