A history of solar activity over millennia
|Author:||Usoskin, Ilya G.1|
1Sodankylä Geophysical Observatory (Oulu Unit), University of Oulu, 90014 Oulu, Finland
|Online Access:||PDF Full Text (PDF, 3.4 MB)|
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe201703061963
|Publish Date:|| 2017-03-06
Presented here is a review of present knowledge of the long-term behavior of solar activity on a multi-millennial timescale, as reconstructed using the indirect proxy method. The concept of solar activity is discussed along with an overview of the special indices used to quantify different aspects of variable solar activity, with special emphasis upon sunspot number. Over long timescales, quantitative information about past solar activity can only be obtained using a method based upon indirect proxies, such as the cosmogenic isotopes ¹⁴C and ¹⁰Be in natural stratified archives (e.g., tree rings or ice cores). We give an historical overview of the development of the proxy-based method for past solar-activity reconstruction over millennia, as well as a description of the modern state. Special attention is paid to the verification and cross-calibration of reconstructions. It is argued that this method of cosmogenic isotopes makes a solid basis for studies of solar variability in the past on a long timescale (centuries to millennia) during the Holocene. A separate section is devoted to reconstructions of strong solar energetic-particle (SEP) events in the past, that suggest that the present-day average SEP flux is broadly consistent with estimates on longer timescales, and that the occurrence of extra-strong events is unlikely. Finally, the main features of the long-term evolution of solar magnetic activity, including the statistics of grand minima and maxima occurrence, are summarized and their possible implications, especially for solar/stellar dynamo theory, are discussed.
Living reviews in solar physics
|Pages:||1 - 97|
|Type of Publication:||
A2 Review article in a scientific journal
|Field of Science:||
115 Astronomy and space science
This work was supported by the Center of Excellence ReSoLVE (Project 272157) of
the Academy of Finland.
|Academy of Finland Grant Number:||
272157 (Academy of Finland Funding decision)
© The Author(s) 2017. This article is published with open access at Springerlink.com
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