The recalibration of the sunspot number series has established a new standard version for sunspot time series that requires updating of prior results based on the calibration. These recent sunspot number corrections mean a change in the results of the previous correlational studies of ISSN with geomagnetic indices, such as the aa-index. In this paper, we investigate the correlation between the old and new sunspot numbers ISSN and SN and their relationship with the aa index through time series, using the methods of Echer et. al (2004), Verma & Trippathi (2016), Stamper et. al (1996), and Feynman (1982).

Coronal mass ejections (CMEs) have become one of the key indicators of solar activity, especially in terms of the consequences of the transient events in the heliosphere. Although CMEs are closely related to the sunspot number (SSN), they are also related to other closed magnetic regions on the Sun such as quiescent filament regions. This makes CMEs a better indicator of solar activity. While sunspots mainly represent the toroidal component of solar magnetism, quiescent filaments (and hence CMEs associated with them) connect the toroidal and poloidal components via the rush-to-the-pole (RTTP) phenomenon. Taking the end of RTTP in each hemisphere as an indicator of solar polarity reversal, it is shown that the north-south reversal asymmetry has a quasi-periodicity of 3-5 solar cycles. Focusing on the geospace consequences of CMEs, it is shown that the maximum CME speeds averaged over Carrington rotation period show good correlation with geomagnetic activity indices such as Dst and aa.

We use the principal component analysis to study geomagnetic activity at annual resolution using a network of 26 magnetic stations in 1966-2015, and an extended network of 40 stations in 1980-2015. The first principal component describes the long-term evolution of global geomagnetic activity, and has an excellent correlation with indices like the Kp/Ap index. The two networks give identical results for the first principal component. The second principal component is highly correlated with the annual percentage of high-speed streams (HSS). The extended network has a slightly higher sensitivity to HSSs. We verify the non-trivial latitudinal distribution of the second empirical orthogonal function. We find that the amplitude of the 22-year variation of geomagnetic activity has a closely similar latitudinal distribution as the second empirical orthogonal function. This verifies that the 22-year variation of geomagnetic activity is related to HSSs. The most likely cause is the Russell-McPherron mechanism.

Mechanisms underlying effects of physical factors on twin births are unclear. The present work studied an association between monthly and yearly multiple birth rates (MBRs) in the Novosibirsk region, south-west Siberia, in relation to solar activity (sunspot numbers) and geomagnetic activity (Ap index) from 1957 to 2008. The difference was verified by comparing the yearly MBR observed in 3-year peaks (M = 7.36, SD = 0.33 per 1,000 births) and 3-year troughs (M = 8.10, SD = 0.31 per 1,000 births, p < .001) of an 11-year solar cycle. An inverse correlation (r = –.60, p < .001) was found between sunspot numbers and MBR for a lag of 1 year. Cross-spectral analysis of a 52-year time series established a common signal with the period of 10.5 years, as well as high coherence (K(2) = 0.87). The multiple regression analysis revealed a significant interaction of solar and geomagnetic effects upon the frequency of twin maternities. The results show that elevated solar activity within the 11-year cycle coinciding with the time of conception inhibits multiple births in a manner depending on geomagnetic activity. It is hypothesized that the likely mechanism underlying the association is early fetal loss induced by solar radiation/flux and its terrestrial mediators.

A group of 86 healthy volunteers was examined in periods of high solar and geomagnetic activity. In this study hourly Dst-index values and hourly data about intensity of cosmic rays were used. Results revealed statistically significant increments for the mean systolic and diastolic blood pressure, pulse pressure and subjective psycho-physiological complaints of the group with geomagnetic activity increase and cosmic rays intensity decrease.