A. Provenzale

The CaCO3 profiles of deep and shallow mediterranean sea cores as indicators of past solar-terrestrial relationships

SummaryWe study the total carbonate profiles of three coastal cores extracted from the continental shelf in the Ionian Sea and of two deep-sea cores extracted from the Tyrrhenian abissal plane. An overall similarity between the two deep-sea profiles and among the three coastal profiles is observed, indicating the complete reproductibility of this type of experimental measurements. In the case of the coastal cores, a constant sedimentation rates=(0.0646±0.0007) cm/y has been determined by radiometric methods and by tephroanalysis. For the deep-sea cores, the spectra of the upper and lower halves of the carbonate depth profiles display the same periodic components, suggesting that the sedimentation rate is nearly the same along the entire deep cores as well. The use of a careful tephroanalysis, the recognition of the Ignimbrite layers of Campanian origin at the expected depths and the similarity between the upper part (5000y) of the carbonate profile of the deep-sea core with that of the coastal cores provide the indication that, on the average, 1 cm of sediment is deposited in about 100 y. We show that the trend of the carbonate record in the deep-sea core is well approximated by a signal obtained by linearly superposing the obliquity and the precession parameters of the Earth rotation axis. Since these astronomical factors contribute to the temporal variations of the Earth insolation, and since the CaCO3 content of the sediment is presumably affected by climatic factors, this result supports the evidence of astronomical control on the Earths climate, as already pointed out by several authors who analysed the power spectra of δ18O, δD and CO2 temporal series from sediment and ice cores. After removal of the «astronomical» trend, the carbonate record displays a dominant periodicity at approximately 12000 y. The 12000 y wave, taken with the opposite sign, corresponds to the trend of the radiocarbon record in tree-rings. This result becomes particularly relevant in view of the existence of common periodicities of about 200 y waves (Suess wiggles) which have already been detected in the carbonate profiles of the coastal cores and in tree-ring radiocarbon data.

On the Presence of Regular Periodicities in the Thermoluminescence Profile of a Recent Sea Sediment Core

We briefly discuss how the thermoluminescence (TL) profile of a young marine sediment provides phenomenological information on the changes in the environmental conditions in the past 18 centuries. The main periodicities present in the TL profile are studied and the similarities between the TL variations and the fluctuations in the contemporary tree-ring A14C signal are considered. An interesting result is the presence, in the TL data, of a well-defined 11-year cycle which is stable and ‘in phase’ for the entire period analysed. We also discuss how four dominant periodicities present in the TL data may be rewritten as the sum of an 11.4-year and of an 82.6- year cycle (reminiscent respectively of the Schwabe and of the Gleissberg cycles of solar activity), which are both amplitude modulated by a 206-year wave. This last periodicity has already been shown to play a dominant role in the A14C record. These results suggest that the TL profiles of recent marine sediments may be successfully used as a new line of evidence for solar variability in the past centuries.

The thermoluminescence profile of a recent sea sediment core and the solar variability

The analysis of the thermoluminescence (TL) profile of the GT14 recent sea sedimentary core shows the existence of four main periodicities of 137.7, 59,12.06, and 10.8 years. Here we discuss the affinity of these waves to the known cycles of solar variability. The beats of the two high frequency components produce a modulated wavetrain with a carrier wave of 11.4 years and an amplitude modulation with period 206 years. The minima of this squared amplitude modulation fall in 1810 and 1913 A.D. and closely correspond to the periods of lowest solar activity as indicated by the sunspot series. The sum of the two low frequency waves can in turn be rewritten as a component with period 82.6 years which is amplitude modulated by a second component with period of 206 years. The 82.6-yr wave has the period commonly attributed to the Gleissberg cycle of solar activity. The maxima of the 82.6-yr wave occur in agreement with the dates of maximum solar radius as suggested by Gilliland (1981).

On the solar origin of the thermoluminescence profile of the GT14 core

The thermoluminescence (TL) profile of the GT14 Ionian Sea core has been recently analyzed in connection with other records of solar activity. Phenomenological similarities among the TL profile, the radiocarbon record in tree-rings and the variations of the mean anuual sunspot number Rz suggest a solar control of the TL signal. In this paper we consider new readings of the TL profile of the GT14 core which were obtained at different glow temperatures. While the main spectral peaks discussed in previous papers are observed in all readings, a few new significant periodic components may now be separated from the noise background. Among these, a strong 22 yr (Hale) cycle is evident, together with a periodicity of 28.5 yr which has already been detected in the spectrum of the sunspot number series. We finally test the temporal persistency of the main TL periodic components by using a cyclogram method and we explore the effects of background noise by considering the TL profile of bleached samples.

Solar Effects on Underground Muons at 570 hg/cm2

Abstract This paper presents results on the intensity variations of underground muons originated by primary cosmic rays with mean rigidity about 1800 GV. We discuss their sensitivity to various solar effects, and the implications on the size of the solar cavity.