Some questions about STORM_DIR

[wang...@mail.ustc.edu.cn]

Dear Sir or Madam,

I was writing to ask a question about IBTrACS data. I downloaded IBTrACS data in CSV format from the website. Recently when I was working with this data, I noticed that one of the variables, STORM_DIR, was moving in a very different direction from the actual path graph. After drawing the path map with the latitude and longitude variables of IBTrACS, I measured the degree of movement direction of each point with the protractor and the description of STORM_DIR in the description document. The result was greatly different from the data. I was curious about how the variable STORM_DIR was calculated. Why does STORM_DIR differ so much from the move Angle in the path diagram? Could you please answer my questions?

Sincerely,

Chita

[Ken Knapp - NOAA Federal]

Hi 

Could you provide an example of the storm you're analyzing?

Also, please realize that the storm direction is "East of North" so 0 degrees is when the storm is moving to the North and 90 degrees is when the storm is moving to the East.

Thanks-

-Ken 

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[wang...@mail.ustc.edu.cn]

Dear Ken

Thank you very much for your reply. Attached is my example, in which I have written all my doubts.

Looking forward to hearing from you.

Chita

-----原始邮件-----
发件人:"Ken Knapp - NOAA Federal" <ken....@noaa.gov>
发送时间:2022-11-18 21:52:11 (星期五)
收件人: wang...@mail.ustc.edu.cn
抄送: ibtra...@googlegroups.com
主题: Re: [ibtracs-qa] Some questions about STORM_DIR

[Jennifer Gahtan - NOAA Federal]

Hi Chita,

If you are calculating the angle just by using your figures, note that your axes aren't scaled properly relative to one another (0.1 deg lon are drawn to be about equal to 0.5 deg lat). A quick check using trigonometric equations on the lat/lon data supports the storm directions given in the data.

Jennifer

To view this discussion on the web visit https://groups.google.com/d/msgid/ibtracs-qa/1ec6eab3.34a4b.1848f14a65e.Coremail.wangxt613%40mail.ustc.edu.cn.

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Jennifer Gahtan, Ph.D.

Physical Scientist
Climatic Science and Services Division (CSSD)
NOAA's National Centers for Environmental Information (NCEI)
151 Patton Ave. Asheville, NC 28801

jennife...@noaa.gov