AIRS

Frequently Asked Questions


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Q.  Why do I see a high-frequency oscillation in a histogram of the number
of occurances of a given value of water vapor in the 500-600mb layer of
Level 3 data when combining data over a time interval?  

A.  This is a digitization effect due to our compressing the Level 3 data by
rounding to shrink the product file size.

The precision of H2OMMR is 8 bits in the mantissa. This is equivalent to
2 1/2 significant digits. Our effective bin size is ~1/256 of whatever
the value is for a given cell.

How should one create a histogram that does not show this beating?

There are two options:
1) make your bin size >> our bin size
2) make your bin size much smaller than it is now but then only plot
non-empty bins.

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