Solar activity forcing of terrestrial hydrological phenomena

TL;DR

This paper reviews evidence of solar activity's influence on regional climate, especially precipitation in South America, highlighting correlations with sunspot numbers over centuries.

Contribution

It provides a comprehensive review and new analysis linking solar activity to regional hydrological phenomena, including river flow and tree-ring data.

Findings

Strong correlation between sunspot number and river stream flow.

Correlation between sunspot number and tree-ring chronologies.

Solar variability influences regional climate patterns.

Abstract

Recently, the study of the influence of solar activity on the Earth's climate received strong attention, mainly due to the possibility, proposed by several authors, that global warming is not anthropogenic, but is due to an increase in solar activity. Although this possibility has been ruled out, there are strong evidences that solar variability has an influence on Earth's climate, in regional scales. Here we review some of these evidences, focusing in a particular aspect of climate: atmospheric moisture and related quantities like precipitation. In particular, we studied the influence of activity on South American precipitations during centuries. First, we analyzed the stream flow of the Paran\'a and other rivers of the region, and found a very strong correlation with Sunspot Number in decadal time scales. We found a similar correlation between Sunspot Number and tree-ring chronologies, which allows us to extend our study to cover the last two centuries.