Day‐To‐Day Variability of the Neutral Wind Dynamo Observed by ICON: First Results From Conjugate Observations
Brian J. Harding, T. J. Immel, S. B. Mende, Yen‐Jung Wu, Astrid Maute, S. England, R. A. Heelis, J. M. Forbes, Christoph R. Englert, Kenneth D. Marr, John M. Harlander, J. J. Makela, Sabine Frey
Abstract
Abstract First results are presented from the conjugate maneuvers performed by NASA's Ionospheric Connection Explorer (ICON) spacecraft. During each several‐minute maneuver, ICON crosses the magnetic equator, measuring the plasma drift at the ∼600‐km apex of a magnetic field line and the neutral wind profiles (∼90–300 km altitude) along both ends of that field line. The analysis utilizes 149 pairs of maneuvers separated by ∼24 hr but at nearly the same location and local time. Principal component regression reveals that 39 ± 7% and 24 ± 9% of the day‐to‐day variance in the daytime vertical and zonal drift, respectively, is attributable to conjugate neutral winds. The remaining variance is likely driven by external potentials from non‐conjugate winds and geomagnetic activity (median Kp 2−). Zonal winds at 100–113 km and >120 km altitude are the primary drivers of conjugate vertical and zonal drift variance, respectively. These observations can test vertical‐coupling mechanisms in whole‐atmosphere models.