Radar data format

Problems with data in 3DVAR.

Radar data format

Postby olver.hernandez » Wed May 06, 2015 1:27 pm

Hi all,
I'm starting to assimilate radar data into WRF.
I found that the data format is this (taken from http://www2.mmm.ucar.edu/wrf/users/wrfd ... _radar.pdf):
Data-level record (height<m>, Radial_V<m/s>, qc, err, Reflectivity<dbz>, qc, err)

In the example data, we can see some examples of the data:
4730.0 -9.520 0 1.000 17.530 0 1.753
3680.0 -10.940 0 1.000 13.260 0 1.326
2870.0 -10.990 0 1.000 8.310 0 0.831
2320.0 -9.960 0 1.000 13.280 0 1.328

I assume that "qc" means quality control and we need to use 0, but I don't know what is the err variable.
Some people assume that it is observational error, but I'm not sure.
For the radial velocity in the example they use 1, but in the reflectivity they use different values.

Anyone knows what is the meaning of the "err" variable in the rada data file? How we can calculate it?

On the other hand, I don't know if I must include each value of the scan or we need to perform some kind of resampling before to write the radar data. Anyone knows how to perform the resampling (mean, maximum)?
olver.hernandez
 
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Joined: Mon Nov 26, 2012 6:54 am

Re: Radar data format

Postby toshio » Tue Jun 09, 2015 3:21 pm

Yes, they are their errors. In your case they assume that the reflectivity error is 10%

In this presentation (http://www2.mmm.ucar.edu/wrf/users/tuto ... 2JUL08.pdf) Qingnong states:

Radial velocity, reflectivity and their errors:
• Error: standard deviation from values at 3×3 grid points
• Min/Max radial velocity error is 1.0/10.0 ms-1
toshio
 
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Joined: Fri Feb 06, 2015 9:11 am


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