[gradsusr] Generating Ensemble Probabilities Based on Conditional Threshold(s)

Perry, Aaron axp09171 at alumni.northernvermont.edu
Wed Jun 2 11:15:31 EDT 2021


I ended up finding success using the -ncep_norm function in wgrib2 to fix the alternating accumulation intervals hurdle.

Thanks again Jeff for the expert guidance!


Aaron Perry
Meteorologist
Class of '16
Northern Vermont University-Lyndon
(formerly Lyndon State College)
Boston, Mass.
Twitter: @AaronPerryWx<https://twitter.com/AaronPerryWx><https://twitter.com/arnpry><https://twitter.com/AaronPerryWx>
Email: Aaron.Perry at lyndonstate.edu<http://Aaron.Perry@lyndonstate.edu/>

________________________________
From: Perry, Aaron <axp09171 at alumni.northernvermont.edu>
Sent: Wednesday, June 2, 2021 7:36 AM
To: GrADS Users Forum <gradsusr at gradsusr.org>
Subject: Re: [gradsusr] Generating Ensemble Probabilities Based on Conditional Threshold(s)

Hi Jeff!

Thank you very much for your insight!

I am going to take a closer look into the GFS Ensemble GRIB files and see if I can sort out what is happening with the alternating accumulation intervals.

Talk soon,

Aaron Perry
Meteorologist
Class of '16
Northern Vermont University-Lyndon
(formerly Lyndon State College)
Boston, Mass.
Twitter: @AaronPerryWx<https://twitter.com/AaronPerryWx><https://twitter.com/arnpry><https://twitter.com/AaronPerryWx>
Email: Aaron.Perry at lyndonstate.edu<http://Aaron.Perry@lyndonstate.edu/>

________________________________
From: gradsusr <gradsusr-bounces at gradsusr.org> on behalf of Jeff Duda <jeffduda319 at gmail.com>
Sent: Tuesday, June 1, 2021 5:30 PM
To: GrADS Users Forum <gradsusr at gradsusr.org>
Subject: Re: [gradsusr] Generating Ensemble Probabilities Based on Conditional Threshold(s)

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Aaron,
I presume the error occurs during this command:

'define probp01 = 100.0*ave(const(const(maskout(precip,precip-0.01),1),0,-u),e=1,e=30)'

Is that correct?

If so, there could be a discrepancy in the structure of the ensemble dimension in the GEFS files. I'm pretty sure that G(E)FS precipitation is stored as an alternating series of 3- and 6-hour precip accumulation intervals. So during forecast hours that are divisible only by 3 and not 6 (i.e., 3, 9, 15, 21 ...) the GRIB2 identifier for APCPsfc may be different than at the other hours.

What I recommend is running g2ctl on two different valid time GEFS files to see if anything about the output (other than the valid time in the file changes). If it does, then I bet that's what it is, and you'll have to use more clever ways of templating over the member and forecast dimensions.

Jeff Duda

On Tue, Jun 1, 2021 at 2:52 PM Perry, Aaron <axp09171 at alumni.northernvermont.edu<mailto:axp09171 at alumni.northernvermont.edu>> wrote:
Good Afternoon,

I am trying to use the GFS Ensemble to generate probabilities based on conditional thresholds and am running into some trouble.

Initially, I have tried to generate an ensemble mean of the probability of 0.01" of QPF in 3-hourly time increments.

See attached GrADS script (gefs_p01.gs<https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fgefs_p01.gs%2F&data=04%7C01%7Caxp09171%40alumni.northernvermont.edu%7C2af2bb031f6a4070c02108d92544b100%7Cb17e9703dbdd49fa909c03dfd13086af%7C0%7C0%7C637581800111838328%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=zZzvLCZ%2FFzXE0vW4K2fp5HMXCQHrE2kAhCRwmjF6XlA%3D&reserved=0>) and the control file (gefs.ctl) that I am using.

I am receiving the following error messages:

Operation error:  Invalid dimension environment
  Looping dimension does not vary
result is Operation error:  Invalid dimension environment
  Looping dimension does not vary

What am I doing wrong here?

Best,

Aaron Perry
Meteorologist
Class of '16
Northern Vermont University-Lyndon
(formerly Lyndon State College)
Boston, Mass.
Twitter: @AaronPerryWx<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftwitter.com%2FAaronPerryWx&data=04%7C01%7Caxp09171%40alumni.northernvermont.edu%7C2af2bb031f6a4070c02108d92544b100%7Cb17e9703dbdd49fa909c03dfd13086af%7C0%7C0%7C637581800111848322%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=p92KSiM3WhMDTjnrbsocjWkTWYohqto9Fn5kNQeQQh0%3D&reserved=0><https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftwitter.com%2Farnpry&data=04%7C01%7Caxp09171%40alumni.northernvermont.edu%7C2af2bb031f6a4070c02108d92544b100%7Cb17e9703dbdd49fa909c03dfd13086af%7C0%7C0%7C637581800111848322%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=bkBhjk8y1VdOp8DrnneQGgB95gqfA3ij8Gw1HSGSMiA%3D&reserved=0><https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftwitter.com%2FAaronPerryWx&data=04%7C01%7Caxp09171%40alumni.northernvermont.edu%7C2af2bb031f6a4070c02108d92544b100%7Cb17e9703dbdd49fa909c03dfd13086af%7C0%7C0%7C637581800111858315%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=hexSHzsTXRCfSaTa4QTyg4QDmPPasXKT0KUfjsq1OfQ%3D&reserved=0>
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--
Jeff Duda, Research Scientist
University of Colorado Boulder
Cooperative Institute for Research in Environmental Sciences
NOAA/OAR/ESRL/Global Systems Laboratory
Boulder, CO
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