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 3-D structure of the solar wind is strongly dependent upon the Sun’s activity cycle. At low solar activity a bimodal structure is dominant, with a fast and uniform flow at the high latitudes, and slow and variable flows at low latitudes. Around solar maximum, in sharp contrast, variable flows are observed at all latitudes. This last kind of pattern, however, is a relatively short-lived feat...

Heliospheric modulation of galactic cosmic rays links solar cycle activity with neutron monitor count rate on earth. A less direct relation holds between neutron monitor count rate and atmospheric electric field because different atmospheric processes, including fluctuations in the ionosphere, are involved. Although a full quantitative model is still lacking, this link is supported by solid sta...

With the recent overwhelming evidences that solar cycle and activity phenomena strongly influence the earth’s environment and climate (Hiremath 2009a and references there in), it is necessary to understand physics of the solar cycle and activity phenomena. Genesis of the solar cycle and activity phenomena-one of the major unsolved problem in solar physicsremains elusive to the solar community. ...

The Sun is the most important energy source for the Earth. Since the incoming solar radiation is not equally distributed and peaks at low latitudes the climate system is continuously transporting energy towards the polar regions. Any variability in the Sun-Earth system may ultimately cause a climate change. There are two main variability components that are related to the Sun. The first is due ...

The Earth is continually exposed to the cosmic radiation of both solar and galactic origin. Solar eruption and solar activity may affect cosmic radiation flux density which has a secondary effect on the flux of particles in the atmosphere as well. Such one event was recorded in the last week of October 2003, where the measured dose rate of the cosmic radiation in the aircraft ATR 42 was 1.8 tim...

We present observational signatures of solar cycle 25 onset. Those signatures are visibly following a migratory path from high to low latitudes. They had starting points that are asymmetrically offset in each hemisphere at times that are 21–22 years after the corresponding, same polarity, activity bands of solar cycle 23 started their migration. Those bands define the so-called “extended solar ...

Understanding the temporal variation of cosmic radiation and solar activity during the Holocene is essential for studies of the solar-terrestrial relationship. Cosmic-ray produced radionuclides, such as (10)Be and (14)C which are stored in polar ice cores and tree rings, offer the unique opportunity to reconstruct the history of cosmic radiation and solar activity over many millennia. Although ...

A future decline in solar activity would not offset projected global warmingA future decline in solar activity could have larger regional effects in winterTop-down mechanism contributes to Northern Hemisphere regional response.

Solar activity is the dynamic energy source behind all solar phenomena driving space weather. During an active solar period, violent eruptions occur more often on the Sun. The solar flares (SFs) and coronal mass ejections (CMEs) shoot energetic and highly charged particles towards Earth that ensuing ionospheric and geomagnetic disturbances. The some geomagnetic disturbances illuminate night ski...