Solar sensitivity experiments for the pre-industrial time period using the comprehensive global climate model CCSM3 (Community Climate System Model 3) ...

• Main Authors: Varma, Vidya, Prange, Matthias, Lamy, Frank, Merkel, Ute, Schulz, Michael
• Format: Dataset
• Language: English
• Published: PANGAEA 2011
• Subjects: File name; File size; File format; Uniform resource locator/link to file; Center for Marine Environmental Sciences MARUM; Integrierte Analyse zwischeneiszeitlicher Klimadynamik INTERDYNAMIK; Southern Ocean
• Online Access: https://dx.doi.org/10.1594/pangaea.775485; https://doi.pangaea.de/10.1594/PANGAEA.775485

The Southern Hemisphere Westerly Winds (SWW) constitute an important zonal circulation that influences large-scale precipitation patterns and ocean circulation. Variations in their intensity and latitudinal position have been suggested to exert a strong influence on the CO2 budget in the Southern Ocean, thus making them a potential factor affecting the global climate. The possible influence of solar forcing on SWW variability during the Holocene is addressed. Solar sensitivity experiments with a comprehensive global climate model (CCSM3) are carried out to study the response of SWW to solar variability. In addition, It is shown that a high-resolution iron record from the Chilean continental slope (41° S), which is interpreted to reflect changes in the position of the SWW, is significantly correlated with reconstructed solar activity during the past 3000 years. Taken together, the proxy and model results suggest that centennial-scale periods of lower (higher) solar activity caused equatorward (southward) ... : Model runs were carried out with constant solar forcing, with the control run having a total solar irradiance (TSI) value of 1365 W/m**2 and the solar sensitivity experiments with a lower TSI value of 1363 W/m**2 (i.e. reduction by 0.15%). Pre-industrial boundary conditions were applied in all simulations following the protocol established by the Paleoclimate Modelling Intercomparison Project, Phase II (Braconnot et al., 2007, doi:10.5194/cp-3-261-2007). Three sensitivity runs with reduced solar constant and different initial conditions were branched off from the control run (Merkel et al., 2010, doi:10.1016/j.quascirev.2009.11.006). Each sensitivity run was integrated for 70 years, which is a typical timescale for the duration of solar "Grand minima" like the Wolf (1280-1350 AD), Spörer (1450-1550 AD) or Maunder (1645-1715 AD) Minimum. The choice of TSI reduction of 2 W/m**2 between solar maximum and solar minimum in the model experiments is consistent with recent observation and physics based estimates ...