How do I calculate Magnetic Variation for a given Latitude and
Longitude for any given Year?

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Request for Question Clarification by ldcdc-ga on 06 Aug 2002 15:47 PDT

Hi,

I don't know exactly what you're searching for:

1. to learn about a method to calculate the variation
or
2. to find a program to do that for you.

That's why I post this as a clarification request.

I found however a page from a respectable source that might lead you
to the resources you need.

Here's the page from NOAA Space environment center:

http://www.ngdc.noaa.gov/seg/potfld/magmodel.shtml

If all you want are the results then you might want to use this online
software:

http://www.ngdc.noaa.gov/cgi-bin/seg/gmag/fldsnth1.pl

Please note that you will only be able to calculate this for the
1900-2005 period.

For what I've seen they use models to calculate those values. And
these models are constantly reviewed and corrected. I also know that
the magnetism of the Earth is far from being understood. There are
many variables that can't be calculated, so long time predictions
about the Earth's magnetism cannot be calculated yet (just like
weather predictions and earthquakes).

Now, my advice to you is to follow the links on that page.

They will lead you to a few FTP sites from where you can download PC
programs and documentation on available models.

For more information you might try to contact the people in charge of
that page.

Now, if this page is not what you were searching for, then please
explain why so we can see what you're after.

If the information I gave you answers your question, then please ask
Google to give me credit for it (give me the money for the answer) by
contacting them by e-mail: answers-editors@google.com.

If this would be too much trouble for you just notice me to post the
"clarification request" as an "answer".

I sincerely hope this is the answer to your question.  :)

Good luck!

ldcdc-ga


PS. I used tha following search term: "calculate magnetic variation"

Hi. It's me again.

After searching for more information on the subject and reading
carefully the site that I already recommended to you, I realized that
it provides you indeed with the information that you requested.

I waited for a while to hear from you (as you can see), but I thought
that you might be busy. I decided to put that information as an
answer. Another researcher might think that I forgot about the
question and post his own answer. You can see why I wouldn't like
that, I'm sure.  :o)

Again, the site that answers your question is the "National
Geophysical Data Center" located at http://www.ngdc.noaa.gov/.

The section answering your question is the Geomagnetism section,
located at
http://www.ngdc.noaa.gov/seg/potfld/geomag.shtml.

If you want to learn about Earth's magnetism start by reading the FAQ
page: http://www.ngdc.noaa.gov/seg/potfld/faqmag.shtml

If you want to use their online tool that calculates what you magnetic
variation they provide then go to:
http://www.ngdc.noaa.gov/cgi-bin/seg/gmag/fldsnth1.pl

You can find instructions on how to use it at
http://www.ngdc.noaa.gov/seg/potfld/instruct.shtml

If you want to download similar software (to use on your own computer)
or to find out more about the models used then please follow the
instructions on this page:
http://www.ngdc.noaa.gov/seg/potfld/magmodel.shtml

If this doesn't answer your question, please post a clarification
request. I would be happy to provide you with the right answer.

Thank you,

ldcdc-ga