We analyze the temporal variation of the diurnal anisotropy of sub-TeV cosmic-ray intensity observed with the Matsushiro (Japan) underground muon detector over two full solar activity cycles in 1985–2008. We find an anisotropy component in the solar diurnal anisotropy superimposed on the Compton–Getting anisotropy due to Earth’s orbital motion around the Sun. The phase of this additional anisot...

We compare Viking and Mars Atmosphere and Volatile EvolutioN mission (MAVEN) Neutral Gas and Ion Mass Spectrometer (NGIMS) observations of the thermosphere and ionosphere of Mars in order to test predictions of large variations in conditions over the solar cycle and with season. Substantial differences exist between the Viking observations at solar minimum and near aphelion and the MAVEN NGIMS ...

Magnetic helicity of solar active regions is quantified by the twist and writhe of their underlying flux tubes. The twist component, in particular, is believed to be an important determinant of the energetics and dynamics of active regions that ultimately lead to coronal heating and solar eruptive activity. Here, I review the role of active region twist in the context of solar activity – laying...

We present a correlation analysis of GONG p-mode frequencies with nine solar activity indices for the period 1995 August to 1997 August. This study includes spherical harmonic degrees in the range 2 to 150 and the frequency range of 1500-3500 μHz. Using three statistical tests, the measured mean frequency shifts show strong to good correlation with activity indices. A decrease of 0.06 μHz in fr...

Using the Morlet continuous wavelet transform on data over the period 1871-1990, it is found that the global wavelet cross spectra between two solar activity indices and seven major Indian monsoon rainfall time series show significant power around the period of the 11 year solar cycle, passing the χ test of significance proposed by Torrence and Compo (1998) at levels exceeding 95% in 10 out of ...

In this work, with wavelet transform, the author investigates possible connection between global land-ocean temperature and solar activity. The study shows fluctuation characteristics in the global land-ocean temperature change. The modulation action from solar activity plays an important role in the temperature change, and there is a possible association existing in the global land-ocean tempe...

Changes in solar activity are regularly forwarded as an hypothesis to explain the observed global warming over the last century. The support of such claims is largely statistical, as knowledge of the physical relationships is limited. The statistical evidence is revisited. Changing solar activity is a statistically plausible hypothesis for the observed warming, if short-term natural variability...

As our civilization depends increasingly on space-borne assets and on a delicate and vulnerable earth-bound infrastructure, solar activity and its potential impact becomes of increasing importance and relevance. In his famous paper on the Maunder Minimum, Eddy (1976) introduced the notion that the Sun is a variable star on long time scales. After the recent decade of vigorous research based on ...

The relationship between tropical cyclogenesis and solar activity is addressed in this paper, analyzing the relationship between important parameters in the evolution of tropical cyclones as the CAPE, wind shear and relative vorticity, and the Dst geomagnetic index as a parameter of solar activity. The apparent relationship between all this phenomena has a different response depending on the ph...

Context. The Sun and solar-like stars undergo activity cycles for which the underlying mechanisms are not well understood. The oscillations of the Sun are known to vary with its activity cycle and these changes provide diagnostics on the conditions below the photosphere. Kepler has detected oscillations in hundreds of solar-like stars but as of yet, no widespread detection of signatures of magn...