Relating 27-Day Averages of Solar, Interplanetary Medium Parameters, and Geomagnetic Activity Proxies in Solar Cycle 24

Abstract

Correlations between solar, interplanetary medium parameters and geomagnetic activity proxies in 27-day averages (a Bartels' rotation) were analysed for the 2009-2016 time interval. In this analysis, two new proxies were considered: 1) B ZS GSM, calculated as the daily percentage of the IMF southward component along the GSM Z-axis and then averaged every 27 days; 2) four magnetospheric indices (Tindices), calculated from the local North-South (X) contributions of the magnetosphere's cross-tail (TAIL), the symmetric ring current (SRC), the partial ring current (PRC) and the Birkeland current (FAC), derived from Tsyganenko and Sitnov 2005 (TS05) semi-empirical magnetospheric model. Our results suggest that, among the parameters tested in this study, solar facular areas, interplanetary magnetic eld intensity and new proxies derived from TS05 model could be taken into account in an empirical model, with a 27day resolution, to explain geomagnetic activity felt on the Earth's surface in terms of solar surface features and the IMF condition. We further retrieve a clear annual oscillation in series of 27-day-mean values of toward/away asymmetries of geomagnetic activity indices, which can be interpreted in the light of Russell-McPherron hypothesis for the semiannual variation of geomagnetic activity.

Calibration of the Zero Offset of the Fluxgate Magnetometer on Board the Tianwen‐1 Orbiter in the Martian Magnetosheath

“…This might be one reason why the zero offset determined by the Wang method II has calculation errors with a period of ∼27 days, since the nonzero of the median of the magnetic field distribution could introduce calculation errors to the Wang method II (Wang, 2022c). We speculate that the 27-day periodicity of the median of the magnetic field in the Martian magnetosheath might be associated with the 27-day periodicity of the IMF (Castillo et al, 2021).…”

Modulation of Solar Wind Impact on the Earth’s Magnetosphere during the Solar Cycle

“…In fact, such a temporal lag represents the average of the broadly distributed shift times between the two datasets, or, in other words, the time required for the various geo-effective structures to transit from L1 to the Earth. The signature of the 27-day solar rotation is evident in the secondary peaks observed during the minimum period [32,33]. Therefore, to determine the influence of the SW energy on geo-effectiveness, in the following analysis, the energy time series are shifted backward by a time interval with respect to the Dst index: E(t) = E(t + ).…”