SAFARI 2000 Freshwater Wetlands, 1-Deg (Stillwell-Soller et al.) ------------------------------------------------------------------ Abstract -------- The Global Distribution of Freshwater Wetlands data base has been assembled from two data sets: Aselman and Crutzen's (AC) (1989) wetlands data set and Klinger's (pers. comm., 1995) Political Alaska data set. The aim is to provide an accurate, comprehensive and uniform set of files for convenient specification of wetlands in global climate models. The main source of data is AC global maps of percent cover for a variety of wetlands categories at 2.5-degree latitude by 5-degree longitude resolution. There is some reorganization for seasonally varying categories. Using bilinear interpolation, the AC data was interpolated to a standard 1-degree by 1-degree grid. The AC data set is geographically complete except for the Alaska region. At the time the data set was assembled, AC found that there was no appropriate large-scale data for the Alaska region, therefore they had to make crude estimates based on limited and conflicting published sources. To remedy this Klinger's Alaska data for bogs and fens at 1-degree by 1-degree resolution were added to cover this region. Complete information on the Global Distribution of Freshwater Wetlands data set produced by L.M. Stillwell-Soller et al. and distributed through the National Center for Atmospheric Research (NCAR), is available at that following web site: http://www.scd.ucar.edu/isg/lana/wetlands/. ========================================================================= Background Information ---------------------- Investigators: Lana M. Stillwell-Soller lana@scd.ucar.edu Lee Klinger klinger@ucar.edu David Pollard dxp21@psu.edu Starley Thompson starley@ucar.edu Project: SAFARI 2000 Data Set Title: SAFARI 2000 Freshwater Wetlands, 1-Deg (Stillwell-Soller et al.) Site: Southern Africa Westernmost Longitude: 5 Easternmost Longitude: 60 Northernmost Latitude: 5 Southernmost Latitude: -35 Temporal Resolution: Monthly Data Set Citation: Stillwell-Soller, Lana M., Lee F. Klinger, David Pollard, and Starley L. Thompson. 2002. SAFARI 2000 Freshwater Wetlands, 1-Deg (Stillwell-Soller et al.). 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 Set Link: http://www.scd.ucar.edu/isg/lana/wetlands/ ========================================================================= Data File Information --------------------- This data set contains 51 separate ASCII data files (listed below in alphabetical order), each one with an accompanying binary image file. The first part of each filename indicates the wetland category. File names containing the string "_ack" contain merged data from both Aselman & Crutzen and Klinger data sets. Otherwise the files bogs_1x1.dat and fens_1x1.dat contain only the Aselman & Crutzen data. For more information please refer to the original documentation (URL given in the "Legend and Data Source" section of this document). All data values represent percentage area covered by the wetland category. 1. bogs_1x1.dat* --> Bog (Aselman & Crutzen data only) 2. bogs_ack_1x1.dat* --> Bog (merged Aselman & Crutzen and Klinger data) 3. fens_1x1.dat* --> Fen (Aselman & Crutzen data only) 4. fens_ack_1x1.dat* --> Fen (merged Aselman & Crutzen and Klinger data) 5. flood-apr_1x1.dat* --> April seasonal floodplain 6. flood-aug_1x1.dat* --> August seasonal floodplain 7. flood-dec_1x1.dat* --> December seasonal floodplain 8. flood-feb_1x1.dat* --> February seasonal floodplain 9. flood-jan_1x1.dat* --> January seasonal floodplain 10. flood-jul_1x1.dat* --> July seasonal floodplain 11. flood-jun_1x1.dat* --> June seasonal floodplain 12. flood-mar_1x1.dat* --> March seasonal floodplain 13. flood-may_1x1.dat* --> May seasonal floodplain 14. flood-misc_1x1.dat --> floodplains, seasonality could not be determined 15. flood-nov_1x1.dat* --> November seasonal floodplain 16. flood-oct_1x1.dat* --> October seasonal floodplain 17. flood-perm_1x1.dat* --> Permanent floodplain 18. flood-season_1x1.dat --> Seasonal floodplain 19. flood-sep_1x1.dat* --> September seasonal floodplain 20. flood_1x1.dat --> all floodplains, discounting seasonality 21. lakes_1x1.dat --> Lakes 22. marsh_1x1.dat* --> Marsh 23 ricepd-apr_1x1.dat --> April rice paddies 24. ricepd-aug_1x1.dat --> August rice paddies 25. ricepd-dec_1x1.dat --> December rice paddies 26. ricepd-feb_1x1.dat --> February rice paddies 27. ricepd-jan_1x1.dat --> January rice paddies 28. ricepd-jul_1x1.dat --> July rice paddies 29. ricepd-jun_1x1.dat --> June rice paddies 30. ricepd-mar_1x1.dat --> March rice paddies 31. ricepd-may_1x1.dat --> May rice paddies 32. ricepd-nov_1x1.dat --> November rice paddies 33. ricepd-oct_1x1.dat --> October rice paddies 34. ricepd-sep_1x1.dat --> September rice paddies 35. ricepd_1x1.dat --> Rice paddies 36. swamp-apr_1x1.dat* --> April seasonal swamp/marsh 37. swamp-aug_1x1.dat* --> August seasonal swamp/marsh 38. swamp-dec_1x1.dat* --> December seasonal swamp/marsh 39. swamp-feb_1x1.dat* --> February seasonal swamp/marsh 40. swamp-jan_1x1.dat* --> January seasonal swamp/marsh 41. swamp-jul_1x1.dat* --> July seasonal swamp/marsh 42. swamp-jun_1x1.dat* --> Jun seasonal swamp/marsh 43. swamp-mar_1x1.dat* --> March seasonal swamp/marsh 44. swamp-marsh_1x1.dat --> Seasonal swamp/marsh 45. swamp-may_1x1.dat* --> May seasonal swamp/marsh 46. swamp-misc_1x1.dat --> swamps/marshes, seasonality could not be determined 47. swamp-nov_1x1.dat* --> November seasonal swamp/marsh 48. swamp-oct_1x1.dat* --> October seasonal swamp/marsh 59. swamp-sep_1x1.dat* --> September seasonal swamp/marsh 50. swamp_1x1.dat --> Swamp 51. total_1x1.dat --> Total natural wetlands * All values are zero for the subset but, files are included for sake of completeness. ========================================================================= 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 40 Columns 55 UpLeftX 5 UpLeftY 5 LoRightX 60 LoRightY -35 cellsize 1 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 ----------------------- Each ASCII data file has also been converted into a binary image file that can be viewed in any standard image viewing package. The files are single-byte images, no header, 55 columns by 40 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 thelower-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 ------------------------------------------ All data values represent percentage area covered by the wetland category. The original data and documentation may be found at the following URL: http://www.scd.ucar.edu/isg/lana/wetlands/