Possible link between Holocene East Asian monsoon and solar activity obtained from the EMD method

Abstract

Abstract. It is thought that East Asian monsoon (EAM)is linked and sensitive to solar activity. In this paper, we have decomposed the Dongge cave speleothem δ 18 O record (proxy for EAM), and 14 C and 10 Be (proxies for solar activity) time series into variations at different time scales with the empirical mode decomposition (EMD) method to reveal the possible link between the EAM variability and solar activity. There are some common cycles in the EAM and solar variability from centennial to millennial scales, indicating a possible link between EAM and solar activity at these time scales. The correlation between EAM and solar activity is much higher at millennial scales than at centennial scales, which means direct responses to the solar variation are more likely at time scales longer than a few hundred years. At ∼ 30, 60 and 600 yr time scales, the variation in EAM is amplified by the solar amplitude modulation at ∼ 100, 200 and 2200 yr time scales.

Paleoclima do Centro-Oeste do Brasil desde o último período glacial com base em registros isotópicos de espeleotemas

“…The influence of Antarctic temperature on tropical SA precipitation on the other hand is not 53 nearly as clear 6 . Southern Hemisphere (SH) millennial-scale events documented in the isotopic 54 record from Antarctica, such as the Antarctic Isotope Maxima events (AIMs), or the Antarctic 55…”

“…Cold Reversal (ACR) may potentially have affected precipitation in tropical SA, as these events 56 have been documented in glacial records from the Andes as well as in some other proxies from 57 southern SA 6,10,11 . These southern teleconnections, however,…”

“…Hemisphere (NH) temperature, as being responsible for abrupt changes in precipitation over 43 tropical SA 5,6 . This link between tropical SA precipitation and high-latitude temperature is 44 established through changes in the latitudinal position of the Inter-tropical Convergence Zone 45 (ITCZ), which responds to changes in the inter-hemispheric energy balance.…”

“…Similarly, our understanding of 36 millennial-scale variability and abrupt changes in South American precipitation during this 37 transition from glacial to interglacial conditions is still rudimentary. The longest paleoclimate 38 records available [1][2][3][4][5] do not present a chronology and resolution that would allow exploring 39 individual millennial-scale events, while the few high-resolution records in existence only cover 40 limited time intervals 6,7 . 41…”

“…Esses valores correspondem ao material secular em equiçíbrio, para o 232Th/238U é de 3.8. Several studies have shown that monsoon systems and other large-scale convergence zones around the world are influenced by solar variability [1][2][3][4][5][6][7][8][9][10][11][12] , for example, reported that peaks in solar forcing increase the energy input to the surface ocean at subtropical latitudes, thereby enhancing evaporation and near-surface moisture, which is carried by the trade winds to the convergence zones. Through this mechanism convective activity in the regions influenced by the upward branches of Hadley and Walker cells can be intensified, resulting in strengthened regional tropical precipitation regimes due to enhanced solar forcing 8 .…”