A 200-year annually laminated stalagmite record of precipitation seasonality in southeastern China and its linkages to ENSO and PDO

Abstract

In southeastern China (SEC), the precipitation amount produced by the East Asian summer monsoon (EASM) is almost equivalent to that during the non-summer monsoon (NSM) period, both of them significantly affecting agriculture and socioeconomy. Here, we present a seasonally-resolved stalagmite δ18O record (δ18Os) for the interval 1810–2009 AD from E’mei cave, Jiangxi Province, SEC. The comparison between δ18Os and instrumental data indicates that the δ18Os variability is primarily controlled by the precipitation seasonality (i.e., the ratio of EASM/NSM precipitation) modulated by the El Niño/Southern Oscillation (ENSO) on interannual to interdecadal timescales. Higher (lower) δ18Os values thereby correspond to lower (higher) EASM/NSM ratios associated with El Niño (La Niña) events. Significant correlations with ENSO and the Pacific Decadal Oscillation (PDO) indicate that the precipitation seasonality in SEC is remarkably influenced by ocean-atmosphere interactions, with lower (higher) EASM/NSM ratios during warm (cold) phases of ENSO/PDO. The progressive increase in δ18Os since 2005 AD may reflect a strengthening of the central Pacific El Niño under continued anthropogenic global warming. The relationship between seasonal precipitation and δ18Os with ENSO/PDO requires further studies.

The Asian Summer Monsoon: Teleconnections and Forcing Mechanisms—A Review from Chinese Speleothem δ18O Records

“…On annual to decadal timescales, many modern stalagmite δ 18 O records show significant negative correlations with local instrumental EASM or annual precipitation amount for the last 200 years [44,62,63,128,150,178,199,200]. However, there exists a mismatch between speleothem δ 18 O and mean annual rainfall in the south region of the EASM area [54,201]. It has been argued that speleothem δ 18 O changes over the EASM region reflect variations in the ratio of water vapor sourced from the 18 O-depleted Indian Ocean to the nearby 18 O-enriched Western Pacific Ocean-the so-called "circulation effect"-which appears to be controlled by the El Niño-Southern Oscillation (ENSO) cycle [202][203][204].…”

“…Baker et al (2015) [192] suggested that the atmospheric moisture pathway might significantly influence precipitation and speleothem δ 18 O in the monsoonal China. In SE China, especially in the region of "spring persistent rain", speleothem δ 18 O variability seems to be controlled primarily by the seasonality of rainfall (i.e., the ratio of EASM precipitation versus that from the remaining seasons), which is modulated by ENSO on annual to decadal timescales [54,205]. Furthermore, the "circulation effect" may play an important role in Central China, where the ISM and the EASM dominate alternatively on annual to multidecadal scales, depending on the position/strength of the Western Pacific Subtropical High (WPSH) [50].…”

“…Furthermore, the "circulation effect" may play an important role in Central China, where the ISM and the EASM dominate alternatively on annual to multidecadal scales, depending on the position/strength of the Western Pacific Subtropical High (WPSH) [50]. Some speleothem δ 18 O records also show close links with the Pacific Decadal Oscillation (PDO) [54,128,199], WPSH [50,54], and ENSO [54,201]. A range of climate dynamics thus modify speleothem δ 18 O values on annual to centennial scales, further complicating the assessment of its relationship with EASM variability.…”

“…A range of climate dynamics thus modify speleothem δ 18 O values on annual to centennial scales, further complicating the assessment of its relationship with EASM variability. Nevertheless, it can be generalized that when the ENSO is in the cold mode (i.e., La Niña), the WPSH intensifies and/or shifts westward, whereas during the cold mode of the PDO, the EASM tends to transport more moisture from more distal regions into northern regions in China, resulting in lighter speleothem δ 18 O values and vice versa [54,203,205].…”

“…On a decadal scale, the Pacific Decadal Oscillation (PDO) and the ENSO are strongly correlated, with positive PDO indices (warm PDO phase) corresponding to El Niño events (warm ENSO phases) [54]. During the cold phases of PDO and ENSO (La Niña phase), the WPSH weakens and/or shifts eastward, resulting in a tendency by the EASM system to transport moisture from more distal regions into northern China-as reflected by a lower δ 18 O in precipitation [54,203].…”