| Summary: | The Sun is the primary source for Earth’s climate system. Its fluctuations in irradiance are also known to have an impact on climate. In addition, changes in solar activity modulate the atmospheric production rates of cosmogenic radionuclides (e.g. 10Be, 14C, 36Cl) that all eventually deposit to different environmental archives. The signal of the changing solar activity through time can thus be retrieved and measured from these archives, such as ice cores, tree rings, or lake sediments. The Sun can also display a more chaotic behavior by erupting flashes of light, plasma and magnetic fields whereby energetic particles can be accelerated, and sometimes hit Earth. These all can damage our spacecraft technologies, harm astronauts, and also affect transformer, electric, and electronic infrastructures on the ground. In the case of extreme events, they may also pose a challenge to air-travel safety. At the same time, when solar energetic particles enter the atmosphere, they can enhance the production rate of cosmogenic radionuclides. The objectives of this thesis are twofold. First, the potential of using 10Be, 14C, and 36Cl as tracers of extreme solar storms is explored in depth. Second, the common production signal of 10Be and 14C caused by the longer term changes in solar activity is used to synchronize climate records from different environmental archives from different regions in order to assess the relative timing of a prominent climate oscillation, over 11,000 years before present. Two large signatures of cosmic-ray increase date to AD 774/5 and AD 993/4 are conclusively attributed to extreme solar energetic particle events that have hit Earth and left a clear imprint on the production rates of 14C as measured in tree rings all around the world, and of 10Be and 36Cl in ice cores from Greenland and Antarctica. The inferred energy spectrum and flux of particles of these events indicate that they were an order of magnitude stronger than any solar high-energy event observed during the space era. To infer the energy ...
|
|---|