GEFS TC track error/spread verification

[JiayiPeng-NOAA]

Does the MET-TC have the capability to verify GEFS ensemble mean TC track error and spread? The case numbers for track error calculation need to be matched with the case numbers for track spread calculation.

[JohnHalleyGotway]

Hello Jiayi,

Yes, the MET tool named TC-Pairs has the ability to compute a "consensus" track. The "consensus" track is really just an ensemble mean of the specified model tracks... where the location and intensity at each point is the mean of the locations and intensities of the members. So this assumes that you already have ATCF track data for each of the ensemble members, and the member names can be distinguished from one another.

Please search for "consensus" in the TC-Pairs Chapter of the MET User's Guide. That describes the required elements for each consensus dictionary array entry.

However, after generating one or more ensemble mean consensus tracks, they are just processed like any other track. The ensemble SPREAD is not directly evaluated anywhere. I'm wondering how you're anticipating the ensemble track and intensity spread should be evaluated?

I'll tag @KathrynNewman here, my colleague in the DTC who does tropical cyclone evaluation, to see if she has any input on the evaluation of spread.

[JiayiPeng-NOAA]

Hi John, I do not know whether Met-TC has the capability to calculate the spread for TC track and intensity (maximum wind speed). Usually while we calculate the ensemble mean, we also calculate the ensemble spread (either track or intensity). When we verify track errors, we also calculate the statistics for spread with its case-number matching with the track error case-number. Thanks, Jiayi

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On Mon, Jan 10, 2022 at 1:40 PM johnhg ***@***.***> wrote: Hello Jiayi, Yes, the MET tool named TC-Pairs has the ability to compute a "consensus" track. The "consensus" track is really just an ensemble mean of the specified model tracks... where the location and intensity at each point is the mean of the locations and intensities of the members. So this assumes that you already have ATCF track data for each of the ensemble members, and the member names can be distinguished from one another. Please search for "consensus" in the TC-Pairs Chapter <https://met.readthedocs.io/en/latest/Users_Guide/tc-pairs.html#tc-pairs-configuration-file> of the MET User's Guide. That describes the required elements for each consensus dictionary array entry. However, after generating the ensemble mean consensus, it is just processed like any other track. The ensemble *SPREAD* is not directly evaluated anywhere. I'm wondering how you're anticipating the ensemble track and intensity spread should be evaluated? I'll tag @KathrynNewman <https://github.com/KathrynNewman> here, my colleague in the DTC who does tropical cyclone evaluation, to see if she has any input on the evaluation of spread. — Reply to this email directly, view it on GitHub <#1341 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ALRTVNJAGMNTM5OAIYOHP3LUVMRZZANCNFSM5LPHI7UQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[JohnHalleyGotway]

@JiayiPeng-NOAA I read through the issues you posted for the NOAA METplus telecon for 1/24/22.

It's obviously not difficult to compute spread when computing the mean. But the issue is where/how to store the output. While the TC-Pairs tool can compute a consensus "mean" track and intensity forecast, it is not currently computing/storing the spread.

I recommend that we schedule a meeting to dive into these details, as well as METplus Discussion #1304 .

I'm hoping you can step through all of the details behind your comment:
"When we verify track errors, we also calculate the statistics for spread with its case-number matching with the track error case-number."

We can also discuss #1304 and dive into the details of the format of the probability of genesis forecast you're trying to verify.