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

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) shifts of the annual mean SWW.

Model runs were carried out with constant solar forcing, with the control run having a total solar irradiance (TSI) value of 1365 W/m2 and the solar sensitivity experiments with a lower TSI value of 1363 W/m2 (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 (Steinhilber et al., 2009, doi:10.1029/2009GL040142). The data provided are the ensemble mean of the three sensitivity experiments with reduced TSI. See further details for the list of parameter used in NetCDF files.

Supplement to: Varma, Vidya; Prange, Matthias; Lamy, Frank; Merkel, Ute; Schulz, Michael (2011): Solar-forced shifts of the Southern Hemisphere Westerlies during the Holocene. Climate of the Past, 7, 339-347

Identifier
DOI https://doi.org/10.1594/PANGAEA.775485
PID https://hdl.handle.net/10013/epic.38781.d004
Related Identifier https://doi.org/10.5194/cp-7-339-2011
Related Identifier https://doi.org/10.5194/cp-7-985-2011
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.775485
Provenance
Creator Varma, Vidya ORCID logo; Prange, Matthias (ORCID: 0000-0001-5874-756X); Lamy, Frank ORCID logo; Merkel, Ute ORCID logo; Schulz, Michael ORCID logo
Publisher PANGAEA
Publication Year 2011
Funding Reference German Research Foundation https://doi.org/10.13039/501100001659 Crossref Funder ID 25575884 https://gepris.dfg.de/gepris/projekt/25575884 Integrierte Analyse zwischeneiszeitlicher Klimadynamik
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Representation
Language English
Resource Type Supplementary Dataset; Dataset
Format text/tab-separated-values
Size 36 data points
Discipline Earth System Research