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Table 2 Data variances for each type and component in NEC coordinates (HL) or SM coordinates (ML)

From: Sequential modelling of the Earth’s core magnetic field

Component/data type Satellite data Observatory data
ML HL ML HL
X \(v = {9}{\hbox { nT}^2}\) \(v = {100}\,{\mathrm{nT}^2}\) \(v = {16}\,{\mathrm{nT}^2}\) \(v = 36\, \mathrm{nT}^2\)
Y \(v = {9}{\hbox { nT}^2}\) \(v = {81}\,{\mathrm{nT}^2}\) \(v = {16}\,{\mathrm{nT}^2}\) \(v = {25}\,{\mathrm{nT}^2}\)
Z \(v = {16}{\hbox { nT}^2}\) \(v = {81}{\mathrm{nT}^2}\) \(v = {25}\,{\mathrm{nT}^2}\) \(v= {36}\,{\mathrm{nT}^2}\)
  1. Data are initially weighted by the inverse of their variance, before undergoing an iterative Huber-weighting process. These values aim at including unknown signals as well as instrument noise. They correspond to typical level of data misfit in prior studies [see e.g. (Lesur et al. 2015)]