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AQM data units?

Posted: Sat Dec 28, 2019 11:22 pm
by jake9wi
Hello, today I was using McV to view NOAAs AQM products when I noticed some oddity's with the datas units.

The files metadata data say units is "log10.(g.m-3)" which does not make sense. If I multiply log10(1) by X I always get one. Also McV does not seem to recognize this unit as when I display the data no unit is shown.

The file metadata:

Code: Select all

:long_name = "Integrated column particulate matter (fine) (1_Hour Average) @ Specified height level above ground layer";
:units = "log10.(g.m-3)";
:abbreviation = "LIPMF";

Re: AQM data units?

Posted: Thu Jan 02, 2020 5:43 pm
by bobc

I verified that the units of the Integrated_column_particulate_matter_fine_height_above_ground_layer_1_Hour_Average variable in the ds.dustsdc01.bin file has units of "log10.(g.m-3)". McIDAS-V has a set of units that it is familiar with, and "log10.(g.m-3)" isn't one of them. I'll write up an inquiry to see if we can handle this better. Note that some of the other files available on the page you linked contain variables with this same unit, I'm just using ds.dustsdc01.bin as an example.

Looking at and selecting "Column Dust Concentration", it looks like "micrograms/m^3" is the unit used to display this data. If you want to display the data using this unit, you can go to the Formulas panel of the Field Selector and choose the "Miscellaneous > Define a formula" formula. Choose the Image Display display type and click Create Display. In the Field Selector window, enter the following for "formula":


In the Field Selector window that appears, select the field to display and click OK. Taking the log of the variable (in g/m3) multiplied by 1000000 (to get you to micrograms/m3) gives an output with values that seem similar to those on the website.

Does this give you what you were looking for?

Bob Carp
McIDAS Help Desk

Re: AQM data units?

Posted: Thu Jan 02, 2020 8:40 pm
by jake9wi
Bob, yes that is helpful.