All of the MODIS processing software was required to use a set of common formats and routines, to ease compatability. These common factors are based on the use of Process Control Files (PCFs), Metadata Configuration Files (MCFs), the SDP toolkit, Hierarchical Data Format (HDF) and Product Generation Executives (PGEs) which are described below.
The PCF is essentially an indexed list of all of the input and output data filenames and associated paths that are to be used by the code. It is a routine that defines the files to be staged and/or used by the program. The main code accesses the required files using the appropriate index numbers, which are mapped to variable names within the main code. Further PCF details regarding the format and contents are available.
The PCFs are automatically generated by EOS during data processing: the files listed within them depend on the location, day and time of data acquisition, and the available ancillary data. For code processing outside of the EOS framework, extra code must be written to generate these PCFs.
There is a PCF associated with each of the six main components of the MODIS ocean processing code. All PCFs have the filename extension ".pcf".
The PCF is a requirement for the Process Control (PC) tools in the SDP toolkit (described below), enabling input/output functions to occur. The correct PCF is set using the command:
setenv PGS_PC_INFO_FILE path/PCFname,
where path is the path where the PCF resides, and PCFname is
the name of the appropriate PCF (e.g. PGE09.pcf).
The MCFs are used to specify metadata at the granule level. Metadata values can be specified to be the same for all granules, or to differ based on information in the PCF. For further information on MCFs and metadata, see the EOS Instrument Team Information Page on Metadata. MCF examples can be found in the Version 1 Template MCF Guide.
The SDP Toolkit is a set of C and FORTRAN 77 routines created for EOS to handle some of the basic functions. It is the interface between the science software and the main system: the Science Data Production System (SDPS). It was designed to ease the integration of the science software with the SDPS. The main types of tools available in this toolkit are listed in Table 2: SDP Tools. For further information, see the SDP Toolkit Home Page.
The names for routines in these tools have the format "PGS_***_function", where *** is the tool code (e.g. PC for the process control tool, or IO_Gen for the input/output tool) and function is replaced by a name defining the particular routine. An example SDP routine name is "PGS_IO_Gen_Open". Any subroutines or functions called within the MODIS processing code that have this naming format are SDP tools.
The toolkit (version 5.2.4v1.00) is currently compatible with the Silicon Graphics IRIX 6.5.3. Permission to obtain a copy of this toolkit may be requested from : pgstlkit@eos.hitc.com.
The MODIS ocean processing code was originally designed to output data in DSP (DISPLAY) format. To conform with EOS requirements, these output files were then converted to HDF-EOS. HDF-EOS files are HDF files with metadata included. These files contain information that describes the location of the data within the file. The code requires both DSP and HDF libraries (HDF toolkit version 4.1r1). The HDF-EOS files can be read using standard HDF tools. Suggestions of useful processing software that can read HDF files can be found in the section titled : Viewing The Data.
Each of the programs detailed here (such as MODCOL and MODSST) are referred to as a numbered PGE in EOS documentation. The relevant PGE numbers have been included in the relevant sections for completeness.
Further information on EOSDIS requirements can be found at three locations :
Documented by Jasmine S. Bartlett, COAS, Oregon State University.