Magnetic observatory data and metadata : types and availability

The availability of magnetic observatory
data has evolved rapidly with the transition of observatories
from analogue photographic magnetograms
to digital electronic recordings, and the advent of
the internet for instant global access to information
of every sort. Metadata (information about the
data) is undergoing its own transformation in order to
accompany the rapid and extensive dissemination of
these data. This chapter describes the types of data
historically and currently produced by geomagnetic
observatories and introduces new data types such as
one-second and quasi-absolute data recently discussed
at the 11th IAGA Scientific Assembly in Sopron,
Hungary.We review the availability of these data types
from the World Data Centres, INTERMAGNET and
other sources. Finally, we discuss developments in
metadata describing the current efforts in the geomagnetism
community to gather, store and distribute this
information about the data to better assist scientific
discovery.