Interdecadal-to-Centennial Variations in Temperature over SubtropicalArgentina and the Solar Forcing

AGOSTA, EDUARDO ANDRÉS; BARRUCAND, MARIANA; BETTOLLI, MARIA LAURA

Malargüe, Mendoza, Argentina

Simposio; Simposio Internacional sobre Variaciones climáticas enAmérica del Sur durante el Holoceno Tardío; 2006

The relationship between the solar forcing and observed temperature and precipitation series from subtropical Argentina, north of 40°S, is explored using the Galactic Cosmic Rays (GCR) as a proxy data of solar forcing at interannual to multidecadal scales. The relationship is also analyzed in temperature and precipitation long reference series using reconstructed isotope Be10-solar forcing (Bard et al. 2000). Temperature series are highly associated to interdecadal variations of the solar forcing via the quasi-11-year solar cycle. The link can be direct or indirect, with varying phase along the annual cycle and during the century. The signal in precipitation does  not seem to be clear enough as in temperature, at least linearly. Atmospheric variables are analyzed according to the phase (high or low) of the GCR flux. Some of the interdecadal changes in temperature could be attributed to thermal advection and/or to irradiative forcing under clear sky conditions, all these provoked by the dynamics of the circulation. The atmospheric circulation anomalies could be induced by the GCR ionization effects on the Atmosphere and/or to solar irradiance effects on propagation of Rossby waves in the troposphere (Shindell et al. 2001). A fraction of the warming observed in subtropical eastern Argentina since mid-19th century could be attributed to the centennial variation of solar forcing.