Geomagnetism: Difference between revisions
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Magnetism is an ever present phenomenon in our daily lives. More so in some geo/cartographic contexts. Providing a way to add magnetic information to our GRASS projects might be helpful. | |||
Here is a gathering of ideas, in order to produce geomagnetic modules or scripts to GRASS | Here is a gathering of ideas, in order to produce geomagnetic modules or scripts to GRASS | ||
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The California Soil Resource Lab has some quite interesting information for production of a | The California Soil Resource Lab has some quite interesting information for production of a | ||
[http://casoilresource.lawr.ucdavis.edu/drupal/node/560 | [http://casoilresource.lawr.ucdavis.edu/drupal/node/560 Detailed Magnetic Declination] map. | ||
As Dylan points out in his post, Stefan Maus has put together an excellent website on the [http://geomag.org/info/declination.html Historical main field change and declination]. (This sentence shamelessly pasted from Dylan's blog) | |||
They also cite the NOAA website, which has [http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html IGRF] and [http://www.ngdc.noaa.gov/geomag/WMM/soft.shtml WMM] computer models available for download (registration not necessary). They also have several [http://www.ngdc.noaa.gov/geomag/geom_util/utilities_home.shtml utility programs]. | |||
The USGS has a [http://pubs.usgs.gov/of/1997/ofr-97-0725/ collection of software], however it dates of 1997. This Open-File Report (97-725) is named '''Potential-Field Geophysical Software for the PC, version 2.2''' and supersedes [http://pubs.usgs.gov/of/1995/ofr-95-0077/of-95-77.html Open-File Report 95-77], from 1995, '''A bibliography of some geophysical computer programs, databases, and maps from the U.S. Geological Survey, 1971-1994'''. | |||
The [http://www.on.br Brazilian National Observatory] (ON) also had its own geomagnetic model, called ELEMAG, which agrees with the IGRF, but is calibrated to work only in Brazil. I ([[User:Pmarc|Pmarc]]) however, have not been able to find it on their website, on the other hand, [http://www.google.com/search?q=Declinação+elemag+on Google] was able to find some versions online. | |||
== Tips == | |||
* Rotating a [[IconSymbols|north arrow symbol]] by a given amount can be accomplished using the '''d.graph''' module or in a '''[[Ps.map_scripts#Creating_a_fancy_North_Arrow|ps.map]]''' plot using a specified rotation angle. | |||
The [http:// | * The {{Cmd|d.rast.arrow}} module and {{AddonCmd|d.barb}} addon module may be of use for [http://grass.osgeo.org/grass62/screenshots/images/d_rast_arrow_magnitude.png visualizing] gravity fields. | ||
== Wishlist == | == Wishlist == | ||
* Module capable of computing the magnetic field (all 7 components) over a location, for a given date or range of dates. It seems to me ([[User:Pmarc|Pmarc]]) that the most appropriate output would be a vector map. The starting point could be the IGRF model provided by NOAA (link above) | * Module capable of computing the magnetic field (all 7 components) over a location, for a given date or range of dates. It seems to me ([[User:Pmarc|Pmarc]]) that the most appropriate output would be a vector map. The starting point could be the IGRF model provided by NOAA (link above) | ||
Latest revision as of 14:28, 19 May 2012
Magnetism is an ever present phenomenon in our daily lives. More so in some geo/cartographic contexts. Providing a way to add magnetic information to our GRASS projects might be helpful.
Here is a gathering of ideas, in order to produce geomagnetic modules or scripts to GRASS
Interesting Links
The California Soil Resource Lab has some quite interesting information for production of a Detailed Magnetic Declination map.
As Dylan points out in his post, Stefan Maus has put together an excellent website on the Historical main field change and declination. (This sentence shamelessly pasted from Dylan's blog)
They also cite the NOAA website, which has IGRF and WMM computer models available for download (registration not necessary). They also have several utility programs.
The USGS has a collection of software, however it dates of 1997. This Open-File Report (97-725) is named Potential-Field Geophysical Software for the PC, version 2.2 and supersedes Open-File Report 95-77, from 1995, A bibliography of some geophysical computer programs, databases, and maps from the U.S. Geological Survey, 1971-1994.
The Brazilian National Observatory (ON) also had its own geomagnetic model, called ELEMAG, which agrees with the IGRF, but is calibrated to work only in Brazil. I (Pmarc) however, have not been able to find it on their website, on the other hand, Google was able to find some versions online.
Tips
- Rotating a north arrow symbol by a given amount can be accomplished using the d.graph module or in a ps.map plot using a specified rotation angle.
- The d.rast.arrow module and d.barb addon module may be of use for visualizing gravity fields.
Wishlist
- Module capable of computing the magnetic field (all 7 components) over a location, for a given date or range of dates. It seems to me (Pmarc) that the most appropriate output would be a vector map. The starting point could be the IGRF model provided by NOAA (link above)