Where is North?

To find your way using a magnetic
compass with a map, you need to know
the difference between magnetic north
and map north. This difference is called
‘grid magnetic angle’, and in the UK it is
derived from a model of the Earth’s magnetic
field, which is updated every year. The variation
To go north, you just follow your compass towards magnetic
north, right? Not quite. Geophysicists have to work hard so
we can continue to navigate with map and compass. Susan
Macmillan and Tom Shanahan describe how the UK magnetic
repeat station network helps.
in grid magnetic angle reflects changes in the
Earth’s magnetic field arising from sources
in the Earth’s fluid outer core. We don’t yet
understand these changes well enough to make
good forecasts, so we need to monitor them
continuously.