Naslov
Estimation of influence of unequal secular variation on geomagnetic data reduction

Autori
Vujić, Eugen ; Brkić, Mario

Izvornik
Studia geophysica et geodaetica (0039-3169) 60 (2016), 1; 162-176

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
geomagnetic observatory; monthly means; annual means

Sažetak
The geomagnetic field components are periodically measured at repeat stations. The main objective of the repeat stations is to give data for tracing of secular variation of the geomagnetic field components. Secular variation is generally different at the repeat station and at geomagnetic observatory used in the data reduction. The influence of the secular variation differences on geomagnetic data reduction was estimated for the regions of Europe, North America (below 60 °N) and Australia, respectively, during interval 2000- 2010. These estimations were obtained by using the monthly mean values of north, east and vertical components of geomagnetic field, recorded at geomagnetic observatories. The influences were calculated by using observatories pairs, with distances from 350 km (in Europe) to 3100 km (in North America and Australia). The maximal influences were found to be the smallest in east component in Europe and North America, and vertical component in Australia ; the influences increase with time from a central reduction epoch and they were not constant during mentioned eleven years ; they were less than 1 nT only in Europe, for distances between the observatories up to 1000 km in all three components and for times spanning ±1 month from a central epoch. It was found that their year to year variability is mostly due to the non-eliminated external field residuals in the observatories monthly means ; their influence was up to 3 nT for ±3 months from a central epoch. Further, the real influences were compared to those modeled by IGRF-12 Model. The maximal differences between the real and the modeled values were below 4.5 nT in all three components, for ±3 months from a central epoch.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Geologija, Geodezija

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