Magnetic Declination
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Mark Minton
May 22, 2025, 11:18:12 AMMay 22
to CaveTex, TexasCavers, Southwestern Cavers of the National Speleological Society
Everyone who surveys caves should correct their compass readings for magnetic declination, especially when data for large systems is collected over many years, or even decades. Declination in some areas changes significantly from year to year. NOAA has recently released new magnetic declination maps. See <https://www.ncei.noaa.gov/products/world-magnetic-model>. Attached is a map showing how declination varies worldwide, as well as one showing how much it has changed over 10 years. Their declination calculator for a given location and date is here :<https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml>.
Mark
Jerry
May 23, 2025, 7:17:09 PMMay 23
to CaveTex, TexasCavers, Southwestern Cavers of the National Speleological Society, Mark Minton
It would appear from the 10 Year Declination Change map, that you wouldn't have to worry about magnetic declination if you caved in the Washington, D.C. region. Lucky buggers !!
Jerry.
On Thursday, May 22, 2025 at 09:18:18 AM MDT, Mark Minton <mamint...@gmail.com> wrote:
Everyone who surveys caves should correct their compass readings for magnetic declination, especially when data for large systems is collected over many years, or even decades. Declination in some areas changes significantly from year to year. NOAA has recently released new magnetic declination maps. See <https://www.ncei.noaa.gov/products/world-magnetic-model>. Attached is a map showing how declination varies worldwide, as well as one showing how much it has changed over 10 years. Their declination calculator for a given location and date is here :<https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml>.
Mark
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Mark Minton
May 25, 2025, 6:44:59 PMMay 25
to Jerry, CaveTex, TexasCavers, Southwestern Cavers of the National Speleological Society
Not too lucky—there’s no limestone there! They do have a few talus caves, one of which I’ve been to.
Mark
It would appear from the 10 Year Declination Change map, that you wouldn't have to worry about magnetic declination if you caved in the Washington, D.C. region. Lucky buggers !!Jerry.
On Thursday, May 22, 2025 at 09:18:18 AM MDT, Mark Minton <mamint...@gmail.com> wrote:
Everyone who surveys caves should correct their compass readings for magnetic declination, especially when data for large systems is collected over many years, or even decades. Declination in some areas changes significantly from year to year. NOAA has recently released new magnetic declination maps. See <https://www.ncei.noaa.gov/products/world-magnetic-model>. Attached is a map showing how declination varies worldwide, as well as one showing how much it has changed over 10 years. Their declination calculator for a given location and date is here :<https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml>.--Mark
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