SAFARI 2000 Derived Soil Properties, 0.5-Deg (ISRIC-WISE) ---------------------------------------------------------- Abstract -------- The data set consists of a southern Africa subset of the ISRIC-WISE global data set of derived soil properties. The World Inventory of Soil Emission Potentials (WISE) database currently contains data for over 4300 soil profiles collected mostly between 1950 and 1995. This database has been used to generate a series of uniform data sets of derived soil properties for each of the 106 soil units considered in the Soil Map of the World (FAO-UNESCO, 1974). These data sets were then linked to a 1/2 degree longitude by 1/2 degree latitude version of the edited and digital Soil Map of the World (FAO, 1995) to generate GIS raster image files for the following variables: Total available water capacity (mm water per 1 m soil depth) soil organic carbon density (kg C/m**2 for 0-30cm depth range) soil organic carbon density (kg C/m**2 for 0-100cm depth range) soil carbonate carbon density (kg C/m**2 for 0-100cm depth range) soil pH (0-30 cm depth range) soil pH (30-100 cm depth range) ========================================================================= Background Information ---------------------- Investigators: Niels H. Batjes batjes@isric.nl Project: SAFARI 2000 Data Set Title: SAFARI 2000 Derived Soil Properties, 0.5-Deg (ISRIC-WISE) Site: Southern Africa Westernmost Longitude: 5 Easternmost Longitude: 60 Northernmost Latitude: 5 Southernmost Latitude: -35 Data Set Citation: Batjes, N. H. 2002. SAFARI 2000 Derived Soil Properties, 0.5-Deg (ISRIC-WISE). Available on-line [http://www.daac.ornl.gov] from the Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. Southern African subset extractions of this data were performed by Oak Ridge National Laboratory: ORNL DAAC User Services Office ornldaac@ornl.gov +1 (865) 241-3952 ========================================================================= Data File Information --------------------- This data set consists of 6 separate ASCII data files, each one with an accompanying binary image file: 1. wise_cac.dat --> soil carbonate carbon density (0-100 cm) 2. wise_ph1.dat --> topsoil pH (0-30cm) 3. wise_ph2.dat --> subsoil pH (30-100cm) 4. wise_sc1.dat --> soil organic carbon density (0-30cm) 5. wise_sc2.dat --> soil organic carbon density (0-100cm) 6. wise_awc.dat --> soil moisture retention (0-100 cm) ========================================================================= ASCII File Information ---------------------- The data files are in ASCII Grid format for ArcInfo. Each file contains a single ASCII array with integer values. Coordinates listed below are in decimal degrees. Rows 80 Columns 110 UpLeftX 5 UpLeftY 5 LoRightX 60 LoRightY -35 cellsize 0.5 Projection geographic The ASCII file consists of header information containing a set of keywords, followed by cell values in row-major order. The file format is: {NCOLS xxx} {NROWS xxx} {XLLCORNER xxx} {YLLCORNER xxx} {CELLSIZE xxx} {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. To import this file into ArcInfo use the following command at an ARC prompt: ASCIIGRID {in_ascii_file} {out_grid} {INT | FLOAT} Arguments: {in_ascii_file} - the ASCII file to be converted. {out_grid} - the 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. Binary File Information ----------------------- The ASCII data files have also been converted into binary image files that can be viewed in any standard image viewing package. The files are single-byte images, no header, 110 columns by 80 rows. Missing data (ASCII -9999) have been converted to the maximum value of 255. File Compression Information --------------------------- For this archive, the data files have been compressed with the MS Windows-standard Zip compression scheme. These files were compressed using Aladdin's DropZip on a Macintosh. DropZip uses the Lempel-Ziv algorithm, also used in Zip and PKZIP programs. The compressed files may be uncompressed using PKZIP (with the -expand option) on MS Windows and UNIX, or with StuffIt Expander on the Mac OS. You can get newer versions from the PKZIP Web site at http://www.pkware.com/shareware/. ========================================================================= Procedure Used to Create the Southern Africa Subset --------------------------------------------------- The original data were obtained and read following the directions in the original documentation. The data were converted to ASCII arrays and then imported into ArcInfo using the ASCIIGRID command. Using GRID (a raster- or cell-based geoprocessing toolbox that is integrated with ArcInfo) the SETWINDOW command was used to define the subarea of interest. This subarea was defined by identifying the bounding coordinates as follows: x_min 5 y_min -35 x_max 60 y_max 5 The "snap_grid" option of the SETWINDOW command was used. This snaps the lower-left corner of the specified window to the lower-left corner of the nearest cell in the snap_grid and snaps the upper-right corner of the specified window to the upper-right corner of the nearest cell in the snap_grid. In this case the snap_grid is an original data grid. The purpose of this is to ensure the proper registration of the newly set analysis window. The command format used is as follows: SETWINDOW x_min y_min x_max y_max original_grid Once the window was set, creating the new grid was simply a matter of setting the new subset grid equal to the original grid. subset_grid = original_grid An ASCII array was created from the new subset grid using the GRID command GRIDASCII. file.dat = GRIDASCII(subset_grid) ========================================================================= Legend & Additional Sources of Information ------------------------------------------ The following legends are used in the original data: wise_cac.dat & wise_sc1.dat & wise_sc2.dat 0: Background 1: 0-4 kg C m-2 2: 4-8 kg C m-2 3: 8-12 kg C m-2 4: 12-16 kg C m-2 5: 16-24 kg C m-2 6: 24-36 kg C m-2 7: 36-48 kg C m-2 8: >48 kg C m-2 9: Glaciers 10: Oceans & Inland waters wise_ph1.dat & wise_ph2.dat 0: Background 1: pH <= 5.5 2: 5.5 < pH <= 7.3 3: 7.3 < pH <= 8.5 4: 8.5 < pH 5: 4.0 < pH <= 8.5 Complex unit 6: Glaciers 7: Oceans wise_awc.dat 0: Background 1: T <= 60mm/m (>66% of grid;mm m-1) 2: 60 < T <= 90 (>66% of grid;mm m-1) 3: 90 < T <= 120 (>66% of grid;mm m-1) 4: 120 < T <= 150 (>66% of grid;mm m-1) 5: 150 < T <= 200 (>66% of grid;mm m-1) 6: 200 < T < 500 (>66% of grid;mm m-1) 7: T <= 90 Complex (>50% of grid;mm m-1) 8: 90 < T <= 150 Complex (>50% of grid;mm m-1) 9: 150 <= T Complex (>50% of grid;mm m-1) 10: Glaciers (>66% of grid;mm m-1) 11: Oceans (>66% of grid;mm m-1) Although not all of these categories may be represented in the subset of the data, the original legend has been retained. The original data and documentation may be obtained upon request from the International Soil Reference and Information Centre (ISRIC). A pdf document describing the data and listing references may be downloaded from the ISRIC web site ( http://www.isric.nl/WISE.htm [Internet Link]). Original Data Set Citation: Batjes, N.H., 1996. Documentation to ISRIC-WISE global data set of derived soil properties on a 1/2 deg by 1/2 deg grid (Version 1.0). Working Paper and Preprint 96/05, ISRIC, Wageningen.