Solar activity component on dendroclimatoligical proxies

MAUAS, P. J. D.; BUCCINO, A. P.; FLAMENCO, E.; VILLALBA, R.

Mysore

Conferencia; 39th COSPAR Scientific Assembly; 2012

COSPAR

Solar forcing on climate has been reported in several studies although the evidence so far remains inconclusive. Evidence of a solar influence on climate has been traditionally found on records of Northern Hemisphere temperature, or sea surface temperature, usually related to changes in solar irradiance. The influence of solar activity on regional precipitations was also found in experiments with a global climate model. In particular, river streamflows are excellent climatic indicators since they integrate precipitations over large areas. Recently, we found a closed correlation between the Sunspot Number and South American river flows on multidecadal time-scale. Our results imply that higher solar activity brings larger precipitations, both in summer and in wintertime, in a large area covering from southern Brazil to the limit with Patagonia, and from the Andes to the Atlantic Ocean.   On the other hand, tree rings are the most numerous and widelydistributed high-resolution climate archives in South America. Duringthe last decades, reconstructions of temperature, rainfall,streamflow, snow and regional atmospheric circulation based on ringwidth, density and stable isotopes, have been conducted usingtree-ring chronologies from subtropical and temperate forests.In particular,  the growth of several moisture-sensitive species, as Junglans or Cedrela, is limited by precipitations. While the climate-growth relations are complex, these species used in dendrochronology in this area show a noticeablestrong precipitation signal. In this work we analyse the influence of solar activity on South American precipitations during centuries. To do so, we study the relation between the  Sunspot Number and seven tree-ring chronologies from Cedrela and Junglans species of Northwestern Argentina (NOA).