Fadil Inceoglu (AIP)

From Cosmogenic Isotopes to Past Variations in Solar Activity
When Mar 22, 2016 from 11:00 AM to 12:00 PM
  • Special Seminar
  • Colloquium
Where SH Lecture Hall
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Observations of sunspots since 1610 AD and records of cosmogenic nuclide production on Earth show that the solar activity varies with a period of ~11 years. This cyclic activity is also found to be modulated on longer time-scales in connection with grand solar minima and maxima, such as the Maunder Minimum (1645-1715) and the Medieval Maximum (1100-1250), respectively, which coincided with the cold period known as the Little Ice Age (ca. 1500-1850 AD) and the warm Medieval Climate Anomaly (ca. 950-1250 AD) in the North Atlantic region.

Information on solar variations prior to 1610 relies on past production rates of cosmogenic nuclides, such as 10Be and 14C. Cosmogenic nuclides are produced in the atmosphere by interactions of galactic cosmic ray particles from space with atmospheric elements, such as N and O. Their production rates are inversely correlated with solar magnetic activity and the geomagnetic field intensity due to the non-linear shielding effect of the solar magnetic field and the geomagnetic dipole field.

During this talk, I will introduce cosmogenic radionuclides and what we can learn from them, focusing on the occurrence characteristics of grand solar minima and maxima during the Holocene (last ~11 kyr) based on simultaneous changes in solar modulation potential reconstructions from 14C and 10Be records.