Regional Geomagnetic Field Model for Croatia at 2009.5

Geomagnetic data of north, east, and vertical components at Croatian repeat stations and ground survey sites, as well as European geomagnetic observatories and repeat stations, were used to obtain a regional geomagnetic model over Croatia at 2009.5 epoch. Different models were derived, depending on input data, and three modelling techniques were used: Taylor Polynomial, Adjusted Spherical Harmonic Analysis, and Spherical Harmonic Analysis. It was derived that the most accurate model over Croatia was the one when only Croatian data were used, and by using the Adjusted Spherical Harmonic Analysis. Based on Croatian repeat stations’ data in the interval 2007.5–2010.5, and a global Enhanced Magnetic Model, it was possible to estimate the crustal field at those sites. It was also done by taking into account the empirical adjustment for long-term external field variations. The higher crustal field values were found at those stations which are on or close to the Adriatic anomaly.