NOAA KLM User's Guide

Section 9.8.3

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Introduction Page, NOAA KLM TOC, Acronyms
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9.8.3 Aerosol Monthly Mean Field File

The Aerosol Monthly Mean Field File is a gridded file of optical thicknesses and other information. The optical thickness at each gridpoint is the average of the optical thicknesses calculated for each week within the month at that gridpoint. If an analyzed field was updated during the month, then it will be used in the calculation of the monthly mean. File Structure Description

The first record is a header which contains satellite ID, the month, the year, and the number of fields used in the computation of the mean. The remaining records are data records. Each data record contains all data for one latitudinal row. The latitude range is from -70 to 70 degree. The first data record will contain data from the -70 degree latitude row and the second will contain data from the -69 degree row and so on. Each row will begin with information from the -180 degree meridian and progress Eastward to the 179 degrees meridian. Each gridpoint will contain 10 bytes of information thus each record will contain 3600 bytes. Header Record Format

The format of the header record is contained in Table

Table Header Record Format.
Halfword Description Comments
1 Month 1-12
2 Year 1988 - ?
3 Satellite ID 1-8
4 Number of fields used in mean calculation 1-5
5-1800 Spares Data Record Format

Each data record represents one row of latitude with each 5 halfwords representing a specific gridpoint or intersection with a meridian. Table shows the format of the grid intersections in the data record.

Table Grid intersection format.
Halfword Description Comments
1 Average Optical Thickness 0 to2440, -999=land
2 Maximum Weekly Optical Thickness for the Month 0 to2440, 0=land
3 Minimum Weekly Optical Thickness for the Month 0 to2440, 0=land
4 Number of weekly field values which were analyzed from at least 1 retrieval which was less than 8 days old. 0 to 5, 0=land
5 Spare  

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