Data Services:OPeNDAP

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OPeNDAP Data Product Descriptions

Contents


Data Attribute Structure

The DAS has changed in the latest release of the cedar web. The new structure provides more granularity for describing the instrument and parameters. Before these were described using a singe string value with the different components embedded in that string. We have separated that out.

OLD Instrument Attribute Structure:

        KINST {
           String INST_5340 "Millstone Hill Fabry-Perot             0            0            0        MFP";
        }

NEW Instrument Attribute Structure

        KINST {
           String KINST "5340";
           String NAME "Millstone Hill Fabry-Perot";
           String PREFIX "MFP";
           String LATITUDE "42 37'10\"";
           String LONGITUDE "-72 30'29\"";
           String ALTITUDE "0.146";
        }

OLD Parameter Attribute Sturcture

        MPAR_5 {
           String PARAMETER_CODE_800 "Line of sight neutral vel (pos = away) 1. m/s";
        }

NEW Parameter Attribute Structure

        MPAR_5 {
           String CODE "800";
           String SHORTNAME "Vnlos";
           String LONGNAME "Line of sight neutral vel (pos = away)";
           String SCALE "1.";
           String UNIT "m/s";
        }

This will make parsing the attribute structures a lot easier and allow us to provide more information in the attribute structures in the future.

The overall structure of the DAS is as follows:

Attributes {
   Data_Descriptor_for_KINDAT_7001_KINST_5340 {
       KINST {
           String KINST "5340";
           String NAME "Millstone Hill Fabry-Perot";
           String PREFIX "MFP";
           String LATITUDE "42 37'10\"";
           String LONGITUDE "-72 30'29\"";
           String ALTITUDE "0.146";
       }
       JPAR_0 {
           String CODE "153";
           String SHORTNAME "Ref Gd Lat";
           String LONGNAME "Reference geod latitude (N hemi=pos)";
           String SCALE "1.E-02";
           String UNIT "deg";
       }
       ...
       JPAR_x {
       }
       MPAR_0 {
           String CODE "10";
           String SHORTNAME "Yr";
           String LONGNAME "Year (universal time)";
           String SCALE "1.";
           String UNIT "yr";
       }
       ...
       MPAR_y {
       }
   }
   ...
   Data_Descriptor_for_KINDAT_n_KINST_5340 {
   }
}

Data Description Structure

The following is an example of a data structure from OPeNDAP. For each container in the data request, a container representing a cedar data file, there are multiple records. Each record contains a prologue, a JPAR section and an MPAR section.

Dataset {
   Structure {
       Structure {
           Structure {
               Int16 KINST;
               Int16 KINDAT;
               UInt16 IBYRT;
               UInt16 IBDTT;
               UInt16 IBHMT;
               UInt16 IBCST;
               UInt16 IEYRT;
               UInt16 IEDTT;
               UInt16 IEHMT;
               UInt16 IECST;
           } prologue;
           Structure {
               Int16 gdlatr;
               Int16 gdlonr;
               Int16 wavlen;
               Int16 gdra;
           } JPAR;
           Structure {
               Int16 year[19];
               Int16 dayno[19];
               Int16 uth[19];
               Int16 azm[19];
               Int16 elm[19];
               Int16 vnlu[19];
               Int16 e_vnlu[19];
               Int16 tn[19];
               Int16 e_tn[19];
               Int16 nsmpti[19];
               Int16 rbrl[19];
               Int16 chip1[19];
               Int16 vnn[19];
               Int16 e_vnn[19];
               Int16 vne[19];
               Int16 e_vne[19];
           } MPAR;
       } data_record_1;
       ...
       Structure {
       } data_record_n;
   } <container_1>;
   ...
   Structure {
   } <container_y>;
} virtual;