NOAA KLM User's Guide

Section 9.8.5

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Introduction Page, NOAA KLM TOC, Acronyms
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9.8.5 Aerosol Optical Thickness 100 km Analyzed Field Accumulation File

Each field accumulation file consists of an archive of one specific type of field (i.e. 100 km aerosol optical thickness). The number of fields archived at any one time depends on the size of the dataset and is given in the directory. In September 2001, the aerosol optical thickness 100-km analyzed field accumulation file which was archived monthly was replaced with an aerosol optical thickness 100-km field file archived weekly. This means that the individual field files are archived and not bundled into an accumulation file for a full month. The format of the individual fields remains the same.

9.8.5.1 File Structure Description

The first record is a directory which points the user to the position of the first record for each field archived. A pointer to the latest field entered in the file is also provided, the user must check each field to find the field for the time period of interest. The fields are concatenated together in one large file after the directory record.

9.8.5.2 Directory Record Format

Table 9.8.5.2-1 contains the format of the Directory Record.

Table 9.8.5.2-1. Directory Record Format.
Full Word # Quantity
1 # of records in the dataset
2 # of records in each field (NRECS)
3 # of fields in the accumulation file (NFIELDS)
4 Field number of latest field entered in accumulation file
5 Record # of first record of field #1
6 Record # of first record of field #2
4+NFIELDS Record # of first record of field # NFIELDS

9.8.5.3 Data Record Format

The first field in the accumulation file begins at record 2. Consult the dataset format description for the aerosol optical thickness 100 km analyzed field to find the format of the field documentation record and data records. The field documentation record (the first record of each field) should be used in referencing the data records for the field since the field documentation record provides information concerning the organization, size and time period of the field. The logical record size for a field is 10,108 bytes.


Amended September 5, 2001


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