This package includes a program written in C which will read an SSF HDF file. This read program is provided as a template to the user who will need to modify it. The examples provided in the main (SSF_readhdf.c) program are written specifically for SDS(s) and Vdata(s) in SSF files. An ASCII metadata file is delivered with every data granule. The file is written in Object Descriptive Language (ODL) and contains information that is associated with the origin, content, quality, and condition of the data granule. The metadata information contained in the granule metadata file is also included as metadata on the SSF HDF data file. An example of a metadata parameter found in the metadata file and on the SSF HDF file is LOCALGRANULEID, which has a value set to the original granule file name. Information on the structure of the SSF file can be found in the Data Products Catalog (DPC) pages included in this package. This information is also available in the enclosed dump file, CER_SSF_Sample_cccode.dump. Complete parameter descriptions are available in the Collection/User's Guide, which is on-line at URL: http://asd-www/larc.nasa.gov/ceres/collect_guide. NOTE: Starting with data date April 1, 2002, the V003 MODIS-Terra Level-2 Aerosol Product (MOD04_L2) was modified. The MOD04_L2 is an input to the SSF, and parameters SSF-132 through SSF-160 are directly computed from the MOD04_L2. Ranges in the Data Products Catalog pages, DPC_SSF_R3V3.pdf, have been updated to reflect the increases in effective optical depth ranges in the MOD04_L2 starting 4/1/02. Individual data granules contain the ranges appropriate for the data date. The sample included in this package (CER_SSF_Sample_cccode) and the corresponding dump (CER_SSF_Sample_cccode.dump) are representative of data granules prior to 4/1/02 and contain the more restrictive ranges. The MOD04_L2 parameter name change, where Dust_Weighting_Factor_Land was changed to Optical_Depth_Ratio_Small_Land, will not be reflected in the SSF. SSF-135 will remain "PSF-wtd MOD04 dust weighting factor land." However, after 4/1/02 it will be computed from the MOD04_L2 parameter Optical_Depth_Ratio_Small_Land. HDF information, documentation, tutorials, libraries, etc. can be found on-line at the URL: http://hdf.ncsa.uiuc.edu/. The 'hdp' utility, provided in the HDF libraries, will extract information about the contents of the HDF file including the size, type, order, names, and the data itself. Some examples are: hdp -H - provides "help" on how to use the "hdp" utility hdp dumpvd - lists the options and format for viewing Vdatas hdp dumpsds - lists the options and format for viewing SDSs hdp dumpvd [-options] - lists information about the Vdatas found on the specified file hdp dumpsds [-options] - lists information about the SDSs found on the specified file This package consists of the following files: 1) SSF_readhdf.c 2) SSF_readHDFfuncs.c 3) SSF_HDFread.h 4) compile_SSF_readhdf 5) CER_SSF_Sample_cccode.dump 6) CER_SSF_Sample_cccode 7) CER_SSF_Sample_cccode.met 8) DPC_SSF_R3V3.pdf To read the files, first unzip them with Info-Zip software. Information about downloading and using this freeware is available at the following URL: http://www.info-zip.org/pub/infozip/ 'SSF_readhdf.c' is the main program which accesses the HDF reading functions. It consists of six examples of accessing SDS and Vdata structures from the included sample SSF file. Comments are provided throughout the program. This file must be modified if the user wishes to read SDSs or Vdatas other than those in the examples. 'SSF_readHDFfuncs.c' is a file consisting of C functions that are linked with 'SSF_readhdf.c' and calls the HDF functions. 'SSF_HDFread.h' is a header file for 'SSF_readhdf.c' and the SSF HDF read functions. 'compile_SSF_readhdf' is a sample script to compile the C programs in a UNIX environment. The script must be modified for different platforms to properly compile the programs and correctly link the HDF libraries. 'CER_SSF_Sample_cccode.dump' is an ASCII file containing a description of the data in the sample SSF, 'CER_SSF_Sample_cccode'. If a value in the SSF granule is out-of-range or not valid, a default value is inserted in its place. Default values depend on data type. CERES default values are greater than or equal to: INT2 - 32767 INT4 - 2147483647 REAL4 - 3.402823E+38 REAL8 - 1.797693134862315E+308 'CER_SSF_Sample_cccode' is a sample 5-footprint SSF file which is used by the examples in 'SSF_readhdf.c' 'DPC_SSF_R3V3.pdf' is a copy of the CERES Data Product Catalog pages which describe the SSF product. 'CER_SSF_Sample_cccode.met' is the metadata file associated with the sample 5-footprint SSF file To execute 'SSF_readhdf.c': 1) Download and install the HDF libraries from the NCSA web site ( http://hdf.ncsa.uiuc.edu ). This code uses version HDF4.1r3. Other versions of the HDF libraries may not work with this code. NCSA uses the gnu gzip compression utility for some packages. If you do not already have this software, which is needed to uncompress the file, you can obtain it from one of the Gnu mirror sites listed at: http://www.gnu.org/order/ftp.html 2) Edit the sample script 'compile_SSF_readhdf' to link the HDF libraries and compile the C programs. (Check the permissions on this file to make sure execute permission is set for the owner.) 3) Execute the script 'compile_SSF_readhdf' to create the executable SSF read program 'ssf_rd' by typing: source compile_SSF_readhdf or compile_SSF_readhdf (on some systems) 4) Execute the SSF read program by typing: 'ssf_rd' followed by the SSF file name. Example: ssf_rd CER_SSF_Sample_cccode Refer questions and comments to: Atmospheric Science Data Center User and Data Services NASA Langley Research Center MS 157D Hampton, VA 23681-2199 U.S.A. Voice: (757) 864-8656 Fax: (757) 864-8807 E-mail: support-asdc@earthdata.nasa.gov