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Indonesia is an archipelago with more than 17,000 islands. The geomagnetic field value at each location in this country changes over time. Those changes are the result of the continued movements of the fluid materials inside the earth core and in its mantle, and the earth’s crustal movements. An accurate regional geomagnetic model of Indonesia is importantly needed by some government and private sectors e.g. transportation, economy, mining, and defense. The empirical geomagnetic field measurement in Indonesia is conducted by BMKG (Badan Meteorologi, Klimatologi dan Geofisika, or Meteorological, Climatological and Geophysical Agency) every epoch (five years) since 1985. A special case occurred in epoch 2020.0 which was caused by the Covid-19 pandemic across the world including Indonesia. During the pandemic, some repeat stations were not accessible, so they were not involved in the regional geomagnetic model computation in the epoch. The computation finally used only 49 repeat stations. However, the analysis towards the obtained data using the collocated cokriging (CC) method showed a good accuracy. This accuracy comply to the small value of the root mean square error (RMSE) generated from the CC method, namely: 1.08 minutes for the declination, 11.2 minutes for the inclination, and 35.6 nT for the total intensity component. As a result, the regional geomagnetic model of Indonesia for epoch 2020.0 become the main reference until 2025 |
