Table 1 Selection criteria for satellite (Champ and Swarm) and ground observatory data
From: Sequential modelling of the Earth’s core magnetic field
Mag. latitude | \(|\text{mag}. \; \text{lat}.| \ge 55^\circ\) | \(|\text{mag}. \; \text{lat}.| \le 55^\circ\) | ||||
|---|---|---|---|---|---|---|
Data type | Swarm | Champ | Obs. | Swarm | Champ | Obs. |
Time sampling | \({60}\,{\mathrm{s}}\) | \({60}\,{\mathrm{s}}\) | \({1}\,{\mathrm{h}}\) | \({30}\,{\mathrm{s}}\) | \({20}\,{\mathrm{s}}\) | \({1}\,{\mathrm{h}}\) |
Local time | – | – | – | 23:00–5:00 | 23:00–5:00 | 23:00–5:00 |
\(\mathrm {D}_{\text{st}}\) | \([-30: 30]{}\,{\mathrm{nT}}\) | \([-30: 30]{}\,{\mathrm{nT}}\) | \([-30: 10]{}\,\,{\mathrm{nT}}\) | \([-30: 30]{}\,{\mathrm{nT}}\) | \([-30: 30]{}\,{\mathrm{nT}}\) | \([-30: 10]{}\,{\mathrm{nT}}\) |
IMF | \(B^{\mathrm {IMF}}_z> 0\) | \(B^{\mathrm {IMF}}_z> 0\) | \(B^{\mathrm {IMF}}_z> 0\) | \(B^{\mathrm {IMF}}_z> 0\) | \(B^{\mathrm {IMF}}_z> 0\) | \(B^{\mathrm {IMF}}_z> 0\) |
Sunlit area excl. | No | No | Yes | Yes | Yes | Yes |
\(N_{\mathrm {v}}\) | 1,104,672 | 637,561 | 906,513 | 822,246 | 1,004,634 | 1,646,564 |