the doppler velocity dealiasing

[chenuanc]

It seems that the doppler velocity dealiasing of my radar data is not very good, especially at a distance. What should I do more?

[chenuanc]

corrected_vel = pyart.correct.dealias_region_based(nc, interval_splits=3, vel_field='velocity', keep_original=False, nyquist_vel=nyq, centered = True)

[scollis]

Good evening @chenuanc .. I am sorry but in order to help we need a lot more information. Can you provide some plots? what is the nyquist? Is the nyquist set correctly? There is not enough information here.

[rcjackson]

It looks like it's failing at the gap in coverage that's making it look like there is a ring in the middle. The region based dealiasing algorithm will not merge together regions that are split by more than 100 gates in either the range or azimuth. I'd try raising the skip_between_ray and skip_along_ray settings to see if you can get the algorithm to join that outer region in with the inner ring correctly.

[chenuanc]

Thank you all for your reply, I'll try to change these parameters.

[chenuanc]

After I changed the three parameters, I got better results, but near the gap, raising the skip_between_ray and skip_along_ray does not always have a positive effect. How can I accurately remove or change the value of those small areas?

[mgrover1]

@chenuanc - here is an example that was shared on Twitter about how to deal with dual-PRF velocity cleaning issues https://github.com/Soudaaa/correct_catastrophic_errors/blob/main/correcting_catastrophic_errors.ipynb

[chenuanc]

Thank you. I'll check it.

[scollis]

Looks like NEXRAD to me!
having a sounding or other velocity field as a first guess will help
https://arm-doe.github.io/pyart/_modules/pyart/correct/region_dealias.html

@rcjackson do we have an example. Even CMAC might help

[rcjackson]

I've put a reply in his main thread about tweaking the skip ray settings.

[scollis]

<!-- /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4;} @font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {margin:0in; font-size:11.0pt; font-family:"Calibri",sans-serif;} a:link, span.MsoHyperlink {mso-style-priority:99; color:blue; text-decoration:underline;} span.EmailStyle19 {mso-style-type:personal-reply; font-family:"Calibri",sans-serif; color:windowtext;} .MsoChpDefault {mso-style-type:export-only; font-size:10.0pt;} @page WordSection1 {size:8.5in 11.0in; margin:1.0in 1.0in 1.0in 1.0in;} div.WordSection1 {page:WordSection1;} -->I think this is now really getting into radar science. Suggest you take this to:https://openradar.discourse.group/  We are all there but you will find more eyes on the data there… Looks like Dual PRF outliers to me… See https://www.osti.gov/pages/biblio/1371614  From: JJC ***@***.***>Date: Tuesday, November 1, 2022 at 12:10 PMTo: ARM-DOE/pyart ***@***.***>Cc: Scott ***@***.***>, Comment ***@***.***>Subject: Re: [ARM-DOE/pyart] the doppler velocity dealiasing (Discussion #1309)After I changed the three parameters, I got better results, but near the gap, raising the skip_between_ray and skip_along_ray does not always have a positive effect. How can I accurately remove or change the value of those small areas?—Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you commented.Message ID: ***@***.***>