CERES SFC R5-817 Readme File 1.0 Introduction This readme file document provides information on the Clouds and Earth's Radiant Energy System (CERES) SFC data sets. CER_SFC_Terra-MODIS_Edition3A CER_SFC_Aqua-MODIS_Edition3A This document includes the following sections: Section 2.0 - Data Set Description Section 3.0 - Format and Packaging Section 4.0 - Science Parameters Information Section 5.0 - Description of Sample Read Software Section 6.0 - Implementing Sample Read Software Section 7.0 - Sample Output Section 8.0 - Additional Data Information (This section is optional) If users have questions, please contact the Langley ASDC User and Data Services Office at: Atmospheric Science Data Center User and Data Services Office Mail Stop 157D NASA Langley Research Center Hampton, Virginia 23681-2199 U.S.A. E-mail: support-asdc@earthdata.nasa.gov Phone: (757)864-8656 FAX: (757)864-8807 URL: http://eosweb.larc.nasa.gov 2.0 Data Set Description 2.1 Instrumentation Description For a complete description of the CERES experiment and instruments, please refer to the documentation provided at the URL http://ceres.larc.nasa.gov/ 2.2 Data Quality For a discussion regarding the quality of the SFC data sets, please refer to the corresponding Quality Summary Document available from the URL http://eosweb.larc.nasa.gov/PRODOCS/ceres/level3_sfc_table.html. 2.3 Other pertinent information The CERES SFC product is produced from software maintained by the CERES TISA Gridding Data Management Team. 2.4 Science Contact 1. Dr. Norman G. Loeb, CERES Interdisciplinary Principal Investigator NASA Langley Research Center Mail Stop 420 Hampton, Virginia 23681-2199 E-mail: Norman.G.Loeb@nasa.gov FAX: (757)864-7996 Phone: (757)864-5688 2. Mr. David R. Doelling, TISA Working Group Chair NASA Langley Research Center Mail Stop 420 Hampton, VA 23681-2199 E-mail: David.R.Doelling@larc.nasa.gov FAX: (757) 864-7996 Phone: (757) 864-2155 3.0 Format and Packaging This package includes a program, written in C, which will read an SFC HDF file. The examples provided in the main (SFC_readhdf.c) program are written specifically for SDS(s) and Vdata(s) in SFC files. This read program is provided as a template to the user who will need to modify it, if they need to read different SFC parameters. Information on the structure of the SFC file can be found in the Data Products Catalog (DPC) pages. This information is also available in the enclosed dump file, CER_SFC_Sample_R5V2.dump. Complete parameter descriptions are available in the Collection/User's Guide, which is on-line at URL: http://ceres.larc.nasa.gov/collect_guide.php. 3.1 Sample Read Package Contents This package consists of the following files: 1) CER_SFC_Sample_R5V2 2) CER_SFC_Sample_R5V2.dump 3) CER_SFC_Sample_R5V2.met 4) SFC_HDFread.h 5) SFC_readHDFfuncs.c 6) SFC_readhdf.c 7) compile_SFC_readhdf Descriptions for each file is as follows: 1) 'CER_SFC_Sample_R5V2' is a sample 5-footprint SFC file which is used by the examples in 'SFC_readhdf.c' 2)'CER_SFC_Sample_R5V2.dump' is an ASCII file containing a description of the data in the sample SFC, 'CER_SFC_Sample_R5V2'. If a value in the SFC 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 The 'CER_SFC_Sample_R5V2.dump' file includes a list of ALL the data on the 5 footprint sample SFC (128 parameters/SDS's plus header Vdata. The output data are the same as what the user would produce using hdp, but for this example, the CERES Team modified the format of the output from the hdp command to make it easier to read. 3)CER_SFC_Sample_R5V2.met is an ASCII metadata file that 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 SFC HDF data file. An example of a metadata parameter found in the metadata file and on the SFC HDF file is LOCALGRANULEID, which has a value set to the original granule file name. 4)'SFC_HDFread.h' is a header file for 'SFC_readhdf.c' and the SFC HDF read functions. 5)'SFC_readHDFfuncs.c' is a file consisting of C functions that are linked with 'SFC_readhdf.c' and call the HDF functions. 6)'SFC_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 SFC 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. 7)'compile_SFC_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. 3.2 Zip Information To read the files, first unzip them with Info-Zip software. Information about downloading and using this freeware is available at the URL: http://www.info-zip.org/pub/infozip/Info-ZIP.html 3.3 HDF library HDF information, documentation, tutorials, libraries, etc. can be found on-line at the URL http://www.hdfgroup.org. The utility hdp, provided in the HDF libraries, extracts information regarding the HDF file contents, such as the size, type, order, names, and the data itself. Some examples are: hdp -H - provides "help" on how to use the "hdp" utility hdp dumpsds [-options] - lists information about the SDSs found on the specified file hdp dumpvd [-options] - lists information about the Vdatas found on the specified file 3.4 Data Format The SFC data files are written in HDF as collections of SDS(s) and Vdata(s). 3.5 Breakdown of the File Naming Convention The SFC data granules adhere to the following CERES file naming convention: CER_PID_SS_PS_CC.DataDate where: CER = the CERES experiment PID = the CERES product, e.g., SFC SS = the CERES sampling strategy, e.g., Terra-FM2-MODIS, as defined by the CERES experiment. For the SFC, this indicates the satellite and instruments that were the source of the input data into the software system that produced the SFC data. PS = the CERES production strategy, e.g., 'Beta2', as defined by the CERES experiment. 'BetaN' production strategies indicate versions of the product produced with algorithms that are still being validated. SFC data products with BetaN production strategies may only be available for a limited time and cannot be be used to publish. SFC data products with 'EditionN' production strategies usually indicate products that contain validated data with which the user can publish. CC = the product configuration code, e.g., '017018', assigned by the CERES experiment. This code is internal to the CERES project, and is updated whenever the software system producing the product is modified for any reason. Multiple files that are identical in all aspects of the filename except for the 6 digit configuration code differ little, if any, scientifically. Users may, therefore, analyze data from the same sampling strategy and production strategy without regard to configuration code. For a complete history of the changes to the software, see the SFC product Description/Abstract document available from the URL http://eosweb.larc.nasa.gov/PRODOCS/ceres/table_ceres.html DataDate = the date of the data included in the file. For the SFC, this date is in the format YYYYMMDDHH where: YYYY = the four-digit data year, MM = the two-digit month DD = the two-digit day HH = the two-digit hour (00-23) 4.0 Science Parameters Information Refer to the SFC CERES Data Products Catalog pages included with this package (listed under Section 3.1) for the following information for each science parameter: Name Units Type (integer, real, character, etc...) Ranges (minimum and maximum values) Fill values / bad data flags 5.0 Description of Sample Read Software The sample read software in this package is intended only as an example. As both the number of SDSs and Vdatas that make up the SFC product and the number of data records contained on an actual SFC file are large, the sample software only demonstrates reading a limited number of SDSs for the five footprints included in the sample SFC file. The contents of the SFC footprint, along with a list of all the SDS(s) contained on the SFC product, are described in the Data Products Catalog pages discussed in Section 3.1. A note to the user: It is recommended that before modifiying the SFC read program to read different SFC parameters, the user should first compile and run the SFC read program using the sample SFC file as input and compare the results that are created by the read program for each SDS/parameter with the list of values for corresponding parameters in the SFC sample dump file,'CER_SFC_Sample_R5V2.dump'. If this test is successful, then the user should modify the the SFC read program or their own software to read the parameters in which they are interested and run that software using the Sample SFC as input. The values read should be compared to the values of the corresponding parameters in the sample dump file. If both of these test are successful, then the user will be ready to use their altered program with a full size SFC data file. 6.0 Implementing Sample Read Software 6.1 Compiling the Sample Read Software 1. Download and install the HDF libraries from the HDF Group web site http://hdfgroup.org This code uses version HDF4.1r5. Other versions of the HDF libraries may not work with this code. NCSA uses the GNU gzip compression utility for some packages. If necessary, the software needed to uncompress the file can be obtained from one of the GNU mirror sites listed at the URL: http://www.gnu.org/order/ftp.html 2. Edit the sample script 'compile_SFC_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 by typing at the command line (denoted by ">"): > ls -l compile_SFC_readhdf A line similar to the following will be displayed: -rwxr--r-- 1 OWNER GROUP 1450 Mar 6 14:49 compile_SFC_readhdf where OWNER and GROUP are the file owner and group information. The owner executable permission is the x in -rwxr--r--. To set the proper permissions, at the command line type: > chmod 744 compile_SFC_readhdf 3. Execute the script 'compile_SFC_readhdf' to create the executable sfc_rd by typing at the command line: > source compile_SFC_readhdf or, on some systems, type: > compile_SFC_readhdf 6.2 How to Run the Sample Read Software Execute sfc_rd by typing at the command line: > sfc_rd CER_SFC_Sample_R5V2 7.0 Sample Output The following is the screen output generated from executing the sfc_rd program with the provided sample file. Name of HDF file to be read: < CER_SFC_Terra_Sample_R5V2 ********************************************************* * Example 1: * ********************************************************* Hour Box 1 Hour Box Number = 11 Hour Box 2 Hour Box Number = 23 Hour Box 3 Hour Box Number = 35 Hour Box 4 Hour Box Number = 48 Hour Box 5 Hour Box Number = 59 ********************************************************* * Example 2: * ********************************************************* Hour box 1 Surface type percent coverage(1) = 0.000000 Surface type percent coverage(2) = 0.000000 Surface type percent coverage(3) = 0.000000 Surface type percent coverage(4) = 0.000000 Surface type percent coverage(5) = 0.000000 Surface type percent coverage(6) = 0.000000 Surface type percent coverage(7) = 0.000000 Surface type percent coverage(8) = 0.000000 Surface type percent coverage(9) = 0.000000 Surface type percent coverage(10) = 0.000000 Surface type percent coverage(11) = 0.000000 Surface type percent coverage(12) = 0.000000 Surface type percent coverage(13) = 0.000000 Surface type percent coverage(14) = 0.000000 Surface type percent coverage(15) = 0.000000 Surface type percent coverage(16) = 0.000000 Surface type percent coverage(17) = 100.000000 Surface type percent coverage(18) = 0.000000 Surface type percent coverage(19) = 0.000000 Surface type percent coverage(20) = 0.000000 Hour box 2 Surface type percent coverage(1) = 0.000000 Surface type percent coverage(2) = 0.000000 Surface type percent coverage(3) = 0.000000 Surface type percent coverage(4) = 0.000000 Surface type percent coverage(5) = 0.000000 Surface type percent coverage(6) = 0.000000 Surface type percent coverage(7) = 0.000000 Surface type percent coverage(8) = 0.000000 Surface type percent coverage(9) = 0.000000 Surface type percent coverage(10) = 0.000000 Surface type percent coverage(11) = 0.000000 Surface type percent coverage(12) = 0.000000 Surface type percent coverage(13) = 0.000000 Surface type percent coverage(14) = 0.000000 Surface type percent coverage(15) = 0.000000 Surface type percent coverage(16) = 0.000000 Surface type percent coverage(17) = 100.000000 Surface type percent coverage(18) = 0.000000 Surface type percent coverage(19) = 0.000000 Surface type percent coverage(20) = 0.000000 Hour box 3 Surface type percent coverage(1) = 0.000000 Surface type percent coverage(2) = 0.000000 Surface type percent coverage(3) = 0.000000 Surface type percent coverage(4) = 0.000000 Surface type percent coverage(5) = 0.000000 Surface type percent coverage(6) = 0.000000 Surface type percent coverage(7) = 0.000000 Surface type percent coverage(8) = 0.000000 Surface type percent coverage(9) = 0.000000 Surface type percent coverage(10) = 0.000000 Surface type percent coverage(11) = 0.000000 Surface type percent coverage(12) = 0.000000 Surface type percent coverage(13) = 0.000000 Surface type percent coverage(14) = 0.000000 Surface type percent coverage(15) = 0.000000 Surface type percent coverage(16) = 0.000000 Surface type percent coverage(17) = 100.000000 Surface type percent coverage(18) = 0.000000 Surface type percent coverage(19) = 0.000000 Surface type percent coverage(20) = 0.000000 Hour box 4 Surface type percent coverage(1) = 0.000000 Surface type percent coverage(2) = 0.000000 Surface type percent coverage(3) = 0.000000 Surface type percent coverage(4) = 0.000000 Surface type percent coverage(5) = 0.000000 Surface type percent coverage(6) = 0.000000 Surface type percent coverage(7) = 0.000000 Surface type percent coverage(8) = 0.000000 Surface type percent coverage(9) = 0.000000 Surface type percent coverage(10) = 0.000000 Surface type percent coverage(11) = 0.000000 Surface type percent coverage(12) = 0.000000 Surface type percent coverage(13) = 0.000000 Surface type percent coverage(14) = 0.000000 Surface type percent coverage(15) = 0.000000 Surface type percent coverage(16) = 0.000000 Surface type percent coverage(17) = 100.000000 Surface type percent coverage(18) = 0.000000 Surface type percent coverage(19) = 0.000000 Surface type percent coverage(20) = 0.000000 Hour box 5 Surface type percent coverage(1) = 0.000000 Surface type percent coverage(2) = 0.000000 Surface type percent coverage(3) = 0.000000 Surface type percent coverage(4) = 0.000000 Surface type percent coverage(5) = 0.000000 Surface type percent coverage(6) = 0.000000 Surface type percent coverage(7) = 0.000000 Surface type percent coverage(8) = 0.000000 Surface type percent coverage(9) = 0.000000 Surface type percent coverage(10) = 0.000000 Surface type percent coverage(11) = 0.000000 Surface type percent coverage(12) = 0.000000 Surface type percent coverage(13) = 0.000000 Surface type percent coverage(14) = 0.000000 Surface type percent coverage(15) = 0.000000 Surface type percent coverage(16) = 0.000000 Surface type percent coverage(17) = 100.000000 Surface type percent coverage(18) = 0.000000 Surface type percent coverage(19) = 0.000000 Surface type percent coverage(20) = 0.000000 ********************************************************* * Example 3: * ********************************************************* Hour Box 1 csza = 0.884373 Hour Box 2 csza = -0.826137 Hour Box 3 csza = 0.883653 Hour Box 4 csza = -0.887509 Hour Box 5 csza = 0.882960 ********************************************************* * Example 4: * ********************************************************* Hour box 1 TOA SW TotalSky Mean : 169.560120 Std : 44.595367 NumObs : 16 Hour box 2 TOA SW TotalSky Mean : 0.000000 Std : 0.000000 NumObs : 0 Hour box 3 TOA SW TotalSky Mean : 424.274261 Std : 107.956001 NumObs : 18 Hour box 4 TOA SW TotalSky Mean : 0.000000 Std : 0.000000 NumObs : 0 Hour box 5 TOA SW TotalSky Mean : 889.113586 Std : 10.625450 NumObs : 8 ********************************************************* * Example 5: * ********************************************************* ASSOCIATEDPLATFORMSHORTNAME = Terra ********************************************************* * Example 6: * ********************************************************* NUMBEROFRECORDS = 5 8.0 Additional Information Regarding the CERES SFC Data. Last Updated: December 1, 2010 -----------------------------------------------------------------------------