ENSO Variability During the Medieval Climate Anomaly as Recorded by Porites Corals From the Northern South China Sea

Abstract

The El Niño-Southern Oscillation (ENSO) is an inherently unstable climatic oscillation of the tropical Pacific oceanic-atmospheric system between positive (El Niño) and negative (La Niña) phases with a periodicity of 2 to 8 years (Timmermann et al., 2018;Wang & Fiedler, 2006). The impacts of ENSO activity can be transmitted worldwide through atmospheric teleconnections, significantly altering global redistribution of heat and moisture fluxes (

Warming trend during Medieval Climate Anomaly in Tropical Maritim Indonesia: Records from Porites Corals

“…During Medieval climate period intensities of ENSO increase [22] recorded in coral proxies from the South China Seas, this is also shown in coral from Lampung Bay [2] and Mentawai [10] where in the late Medieval period the interannual climate event is clearly shown SST anomaly [2]. The increasing of interannual climate phenomena correlated with the warming trend of SST during Medieval period.…”

Abrupt Increase in ENSO Variability at 700 CE Triggered by Solar Activity

“…(c) 3–7‐year band‐pass filtered Xisha coral Sr/Ca‐SST anomalies (black lines) with uncertainty quantification (gray shading). Red and blue shading represent El Niño and La Niña events, respectively, defined by the asymmetric ENSO threshold (Jiang, Yu, Tao, et al., 2021). (d) Number of El Niño (red line) and La Niña (blue line) events in a sliding 31‐year window.…”

“…Instrumental SST at the Xisha Islands from 1980 to 2007 CE ranged from a minimum of 24.3 ± 0.5 (1ơ) °C in January to a maximum of 29.4 ± 0.3 (1ơ) °C in June, with an annual mean value of 27.4 ± 0.5 (1ơ) °C (Rayner et al., 2003) (Figure S1 in Supporting Information ). Interannual SST in the northern SCS is remotely affected by ENSO activity via the atmospheric and ocean circulation changes, indicating positive and negative SST anomalies during El Niño and La Niña events, respectively (Jiang, Yu, Tao, et al., 2021; Song et al., 2012; Wang et al., 2000) (Figure 1).…”

“…Accordingly, the maximum and minimum coral Sr/Ca values in each annual cycle were assigned to January (highest Sr/Ca) and June (lowest Sr/Ca) in any given year, respectively. Subsequently, coral Sr/Ca records were linearly interpolated into monthly resolved time series with 12 samples per year (Jiang, Yu, Tao, et al., 2021). The coral Sr/Ca values were converted into SST based on a previously established linear regression equation (Jiang, Yu, Tao, et al., 2021): Sr/Ca (mmol/mol) = 10.144 (±0.0016)−0.0497 (±0.0015) × SST (°C).…”

“…Subsequently, coral Sr/Ca records were linearly interpolated into monthly resolved time series with 12 samples per year (Jiang, Yu, Tao, et al., 2021). The coral Sr/Ca values were converted into SST based on a previously established linear regression equation (Jiang, Yu, Tao, et al., 2021): Sr/Ca (mmol/mol) = 10.144 (±0.0016)−0.0497 (±0.0015) × SST (°C). Although the slope value of −0.0497 mmol/mol °C −1 is lower than the average slope from multiple studies of −0.0607 mmol/mol °C −1 (Corrège, 2006), it is very close to the mean value of −0.0499 mmol/mol °C −1 from the SCS (Table S1 in Supporting Information ).…”