Abstract When interplanetary magnetic field discontinuities interact with planetary bow shocks, hot flow anomalies (HFAs) form in the solar wind and can extend into the magnetosheath. Here we reconstruct the three‐dimensional geometry of an HFA bounded by two jet regions in the terrestrial magnetosheath. Using a previously established conceptual model of HFA evolution together with in situ measurements in the magnetosheath and pristine solar wind, we derive the structure’s geometrical characteristics and show that its normal aligns with the discontinuity normal. It spans most of the dayside magnetosheath. Ground magnetometer data corroborate the reconstruction, revealing both the scale of the disturbance and its dusk‐to‐dawn propagation. Notably, one bounding jet reaches 11 RE ${R}_{\mathrm{E}}$ in width, significantly larger than the sizes of typical magnetosheath jets reported in the literature.
Observations from the Little Bunker
Last updated: February 24, 2026 10:22 PM
Atmospheric CO₂
429.9 ppm
+17.3
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