[bashi]

You have to remember that it is a model and can not represent the reality in all aspects or cases.
Because it is a mixed input of
1. fixed input parameters and
2. current measured data.
The fixed inputs are approximations to model the reality and might have been quite good at a specific time, but reality changes. So will the accuracy of the results.

If you would develop a model of a herd of sheep, then you may assume a sheep to be a free mobile round sphere…

Additionally you are getting only quality results out of the modelling, if you are feeding it with quality data sets.
For modelling Earths magnetic field, the International Geomagnetic Reference Field, the IGRF is being used. This data set is being updated regularly every 5 years, last in 2009.

Excerpts from the website:
http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html

International Geomagnetic Reference Field
The IGRF is a series of mathematical models of the Earth's main field and its annual rate of change (secular variation). In source-free regions at the Earth's surface and above, the main field, with sources internal to the Earth, is the negative gradient of a scalar potential V which can be represented by a truncated series expansion:
The 11 th Generation IGRF coefficients were computed from candidate sets of coefficients produced by the participating members of IAGA Working Group V-MOD. Their institutes and the many organisations involved in operating magnetic survey satellites, observatories, magnetic survey programmes and World Data Centers are to be thanked for their continuing support of the IGRF project.
The International Geomagnetic Reference Field (IGRF) was introduced by the International Association of Geomagnetism and Aeronomy (IAGA) in 1968 in response to the demand for a standard spherical harmonic representation of the Earth's main field. The model is updated at 5-yearly intervals, the latest being the 11th generation, produced and released by IAGA Working Group V-MOD (formerly V-8) December 2009. The IGRF has achieved worldwide acceptability as a standard and has proved valuable for many applications, BUT INAPPROPRIATE USE COULD SERIOUSLY DAMAGE THE CREDIBILITY OF YOUR RESULTS !

The Earth's magnetic field crudely resembles that of a central dipole. On the Earth's surface the field varies from being horizontal and of magnitude about 30 000 nT near the equator to vertical and about 60 000 nT near the poles; the root mean square (rms) magnitude of the vector over the surface is about 45 000 nT. The internal geomagnetic field also varies in time, on a time-scale of months and longer, in an as yet unpredictable manner. This so-called secular variation (SV) has a complicated spatial pattern, with a global rms magnitude of about 80 nT/year. Consequently, any numerical model of the geomagnetic field has to have coefficients which vary with time.

When using models, to avoid ambiguity you should state explicitly which IGRF Generation you are using; the error estimates in the following discussion refers to the set of models of the 11th Generation


The IGRF is inevitably an imperfect model. Firstly, the numerical coefficients provided will not be correct: the model field produced will differ from the actual field we are trying to model - "errors of commission". Secondly, because of the truncation, the IGRF models represent only the lower spatial frequencies (longer wavelengths) of the field: higher spatial frequency components of the field are not accounted for in our model - "errors of omission". Thirdly, there are also other contributions to the observed field that the IGRF is NOT trying to model
Secular variation
The geomagnetic field does not vary linearly with time but until 2000, except for a few years round 1980, the use of linear interpolation over 5 years does not significantly increase the above rms errors for the main field. From 2000, linear interpolation might lead to increased errors at certain times.
OTHER CONTRIBUTIONS TO THE OBSERVED FIELD
If you measure the magnetic field at a point on the Earth's surface, do not expect to get the value predicted by the IGRF!
Quite apart from the errors discussed above, there might be fixed contributions from buildings, parked cars, etc., and the magnetization of crustal rocks will certainly add its own local, small-scale, field, typically of magnitude 200 nT, but often much larger.
There are also a large variety of time-varying fields, both man-made (traffic, DC electric trains and trams, etc.) and natural (from electric currents in the ionosphere and magnetosphere), and the associated induced fields from currents induced in the conducting earth. The ionospheric and magnetospheric fields occur at time scales mostly ranging from seconds to hours; in "quiet" conditions they may be as small as 20 nT (though enhanced near the geomagnetic equator and over the polar caps), but up to 1000 nT and more during a magnetic storm. On a longer time scale (days to years), the large-scale magnetic field of the external ring current (approximately represented by the Dst index) will give perhaps 1000 nT during and after a magnetic storm.

So, that said, if you see magnetic lines on the North pole, but the lines are not returning to the South pole, then it does not mean that it connects somewhere with NIBIRU. It is because the already existing anomalies of the Earth field are getting amplified by occasional odd dataset measurement of the satellites, which then are triggering the model to display oddities. That’s a proof of the limitations of the model.

World Mag Maps (very interesting):

http://wdc.kugi.kyoto-u.ac.jp/igrf/index.html



Software:

http://www.ngdc.noaa.gov/IAGA/vmod/geomag70_windows.zip

Dataset:

http://www.ngdc.noaa.gov/IAGA/vmod/igrf11coeffs.txt


.