Hello professors, I would like to ask you a question. I want to convert the CMAQ simulation data into the data corresponding to the satellite data unit, and the METBDY3D.nc file is needed. I would like to ask what is the data corresponding to ZF and DENS in this file respectively?
As indicated by the “var_desc” attributes, ZF is the height above ground at the top of each layer (while ZH is the height above ground at the layer midpoint), and DENS is the dry air density.
Hello, professor, the problem I am facing now is that I do not know what the corresponding data size of this ZF or DENS is, because I need to calculate the number concentration of dry air based on these two, and I get that the CMAQ mesh size is 100 times 92, while I get that the ZF and DENS are 745 times 31 times 388. I know 31 is the boundary story, but what are 745 and 388?
METBDY3D is a file of type BNDARY3 where variables have dimensions of TSTEP, LAY, and PERIM. I/O API file types are documented here. For the case where NTHIK is 1, PERIM is equal to 2*NCOLS + 2*NROWS + 4
If you are after ZF and DENS values not along the perimeter of the domain but throughout the domain, you need to look at METCRO3D, not METBDY3D, since that file is of type GRDDED3 so the variables have dimensions of TSTEP, LAY, NCOLS, and NROWS.
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Hello, I have another question for you, that is, I have transferred the data from January 29 to February 28 with CMAQ, and the time of the CMAQ data is the US time, right? Then I want to compare the simulated data with the Sentinel 5P satellite data, and do I need to convert the time difference
All time information in the CMAQ system (input and output files) is in UTC, as indicated in your CMAQ log files (“Processing Day/Time [YYYYDDD:HHMMSS] … Which is Equivalent to (UTC): …”) and as also stated in the I/O API documentation.
If your satellite data is reported in a different time zone, you will have to handle the necessary conversion.