Past Solar Storms: The links between solar storms and solar activity

Our Sun is a remarkably stable energy source which is crucial for life on Earth. However, we know that the Sun exhibits variations on a wide range of time scales. Occasionally, violent eruptions on the Sun’s surface, so-called solar storms, release energetic particles that can damage our modern society. Nowadays the Sun is constantly monitored and a wealth of information has been obtained about its variability from ground-based and satellite observations. However, our Sun exhibits variations that exceed the range measured during the space era as evidenced from sunspot observations over the past 400 years. Similarly, as demonstrated by historical observations and indirect proxy data, the Sun can produce solar storms orders of magnitudes larger than anything observed during the space era. Presently, we do not know the recurrence rate of large solar storms and how these are linked to solar activity. Mapping out the linkages may help to understand underlying processes and to predict the risks for future events.To achieve this we can take advantage of the “natural detector” of past solar activity – cosmogenic radionuclides in highly resolved and well-dated natural archives. I am proposing to develop this natural cosmic ray detector to increase its detection limit, resolution and reliability for assessing solar storms and solar variability in the past. This involves an assessment of the complete chain from solar energetic particles to cosmogenic radionuclide deposition for ground-truthing of the natural cosmic ray detector. Furthermore, novel ice core sampling and improved analytical methods will allow us to produce an unprecedented database for these studies. We will test hypotheses of the recurrence rate of solar storms and their relationship to solar activity. Our results will extend space weather research to millennial time scales and lead to a ground breaking new understanding of the temporal variability of our star.