Tuesday, October 15, 2013

Paper finds another amplification mechanism by which the Sun controls climate

A paper published in Climate of the Past finds the position of the Southern Hemisphere Westerly Winds, "an important zonal circulation that influences large-scale precipitation patterns and ocean circulation," "is significantly correlated with reconstructed solar activity during the past 3000 years." The paper may represent another solar amplification mechanism by which small changes in solar activity are amplified to large effects on climate.

Horizontal axis is years before the present
Clim. Past, 7, 339-347, 2011
www.clim-past.net/7/339/2011/
doi:10.5194/cp-7-339-2011


Solar-forced shifts of the Southern Hemisphere Westerlies during the Holocene

V. Varma1, M. Prange1,2, F. Lamy2,3, U. Merkel2, and M. Schulz1,2
1Department of Geosciences, University of Bremen, 28334 Bremen, Germany
2MARUM – Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359 Bremen, Germany
3Alfred Wegener Institute for Polar and Marine Research, 27568 Bremerhaven, Germany

Abstract. 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. In the present study, the possible influence of solar forcing on SWW variability during the Holocene is addressed. 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. In addition, solar sensitivity experiments with a comprehensive global climate model (CCSM3) were carried out to study the response of SWW to solar variability. 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.

3 comments:

  1. An equatorward shift in the southern hemisphere (which is where I live), would be a northward shift. Or have I missed something in this post.

    Whatever, the findings of this research are significant.

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  2. http://joannenova.com.au/2013/10/solar-effects-seem-to-shift-wind-and-rainfall-patterns-over-last-3000-years-in-chile/

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  3. “the increase in UV at the maximum solar cycle which gives more ozone in the lower stratosphere and an increase in temperature in that layer mainly in the tropics which pushes the jetstreams poleward”

    The trouble with that is that overall stratospheric ozone decreased during the active sun of the late 20th century.

    Consequently I had to build my New Climate Model on the basis that although ozone above the tropics and at low levels in the stratosphere does increase when the sun is more active that is more than offset by a reduction of ozone higher up and towards the poles when the sun is more active.

    At present I have the only hypothesis which attempts to deal with that conundrum.

    Meanwhile there has been some data obtained which suggests a reversal of the expected solar effect on ozone creation / destruction above 45km.

    I’m curious as to whether future data will firm up on that.

    Stephen Wilde

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