Powerful Millennial-Scale Solar Luminosity Cycles in an Experimental Solar Insolation Record and Their Significance to the Termination- II
Y.Y.Shopov, D. A. Stoykova, D.Ford+, L.N.Georgiev, L.Tsankov. (Faculty of Physics, University of Sofia, James Bouchier 5, Sofia 1164, Bulgaria; ph. ++359(2)625 68 36; Fax: ++359(2)962 52 76; E- Mail: YYShopov@Phys.Uni-Sofia.BG); +(Geography Dept., McMaster Univ., Hamilton, Ontario, L8S 1K4, Canada; ph. ++(905) 546 45 37; Fax: ++(905) 546 04 63; E-mail: dford@mcmail.CIS.McMaster.CA)
Calcite speleothems luminescence depends exponentially upon soil temperatures that are determined primarily by solar visible and infrared radiation. So microzonality of luminescence of speleothems is used as an indirect Solar Insolation (SI) proxy index.
We measured a luminescent solar insolation proxy record in a speleothem (JC11) from Jewel Cave, South Dakota, US. This record covers 89300- 138600 yrs B.P. with high resolution (34 years) and precision of measurements better than 1%. It reveals determination of millennial and century cycles in the record. This TIMS U/Th dated record exhibit a very rapid increasing in solar insolation at 139 kyrs +/- 5.5 kyrs (2 sigma error) responsible for the termination II. This increasing is preceding the one suggested by the Orbital theory with about 10 kyrs and is due to the most powerful cycle of the solar luminosity with duration of 11,5 kyrs superposed on the orbital variations curve. The Devils Hole 18- O record suggests that termination II happened at 140 +/- 3 kyrs. It follows precisely the shape of our experimental solar insolation record. So the Devils Hole record do not disapprove the orbital theory, but suggests, that solar luminosity contribution to the solar insolation curves is severely underestimated. The 18-O record from the same Jewel cave sample represents mostly local paleoclimate and maybe geochemical variations and do not correlate very well with the SI luminescence record and the 18-O Devils Hole record. In opposite the 13-C record measured from the same material correlates well with them. Both isotope JC11 records have resolution ranging from 83.3 yrs (108- 122 kyrs BP), 813 years (90- 108 kyrs BP), to 1000 yrs (122- 133 kyrs BP).
Solar insolation records contains not only orbital variations, but also solar luminosity self variations, producing some very powerful millennial cycles. The most powerful solar luminosity cycle is with duration of 11,5 +/- 1 kyrs and is as powerful as the 23 ka. orbital cycle in our SI proxy record. It was estimated to produce over 6% variation of the total solar radiation at the Earth's surface. Other powerful solar luminosity cycles are with duration of 6000 (3%), 4400 and 3300 years (1.8 % variation of the total solar radiation at the Earth's surface). 7 other millennium cycles have intensity between 1% and 0.4 % of the total solar radiation at the Earth's surface, so they can produce climatic variations with intensity comparable to that of the orbital variations. In result the real solar insolation curve have very complex shape, like the high resolution paleoclimatic curves. The theoretical orbital variation curves are contained in it, but are responsible only for a part of it.