Past Provisional track

Lam Nguyen

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Mar 29, 2023, 11:36:43 AM3/29/23

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Dear IBTrACS Team,

I am doing a comparison between provisional track and best track. May I ask if your team keeps provisional track data in your repository for storms that already have best track at the moment?

Besides, could I ask how often do you update provisional track? and do you store data for each version every time there is an update?

Thank you so much!

Best Regards,

Tung Lam

David Schmid

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Sep 1, 2023, 6:08:12 AM9/1/23

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Dear IBTrACS Team, Dear Tung Lam

Not sure if below question from Tung Lam has been addressed or I just missed it.

I would also be very interested in archived provisional data, to compare it to main/reanalyzed data. Is there already any analysis performed about discrepancies?

Another question: From the column documentation, do I understand correctly that the USA_RMW will not be reanalyzed and therefore I can assume that the USA_RMW will remain stable between provisional and reanalyzed data?

Furthermore, REUNION_RMW and BOM_RMW will be reanalyzed, since there is no such comment as for USA_RMW?

Many thanks and best regards,

David

Ken Knapp - NOAA Federal

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Sep 1, 2023, 8:07:31 AM9/1/23

to David Schmid, IBTrACS Q&A

Hi David

My apologies. The response to Tung Lam was inadvertently sent offline and didn't include this email group. Here's our previous response for the record:

IBTrACS is currently updated twice a week, with new provisional data. However the provisional data isn't necessarily updated but instead new timesteps are added. Best track updates, where the provisional data is replaced with best track data, occur a few times per year and the data is replaced.
IBTrACS does not currently provide provisional data for storms that have best track data available. We do keep old files for provisional data, however this data is not operational or supported.

In short, the provisional data is not readily available.

To your specific questions about RMW. We only receive final data from BoM and La Reunion. We don't have provisional data from those, so any RMW's that they provide are final.

The USA_RMW is available in the provisional data we access. Our source data for the final best track data is NHC/HURDAT2 (for the N Atl and E Pac) and JTWC (for other basins). From the HURDAT2 documentation:

7) Radius of Maximum Wind: These values have been best tracked only starting in 2021. Before 2021, the missing data are denoted as “-999”. Uncertainty in the RMW values – expressed as estimated absolute error in nautical miles – have been provided by a survey of the NHC Hurricane Specialists in 2022 [table available in the document and not pasted here]

It isn't clear to me from the documentation whether JTWC reanalyzes RMW.

I am unaware of any studies that compare provisional data and best track data.

I hope this helps. Please let us know if you have additional questions.

Best regards-

-Ken

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Ken Knapp,

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David Schmid

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Sep 1, 2023, 10:08:42 AM9/1/23

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Hi Ken

Many thanks for your answer. This is very helpful.

Nevertheless, it would be very much appreciated if past provisional data were somehow made available.