Strengthening of paleo‐typhoon and autumn rainfall in Taiwan corresponding to the Southern Oscillation at late Holocene

Abstract

The purpose of this study is to improve prehistoric knowledge of paleo‐typhoon and winter monsoon activity in the western North Pacific after 8 cal. ka BP. We examine two sediment cores derived from lakes located to the south and north of the Ilan Plain in northeastern Taiwan. Seasonal and typhoon rainfall data over the past several decades are collected for this study region. We also use mineral indicators, K/Rb ratios and grain size to estimate sediment sources, intensity of chemical weathering and rainfall intensity. The results show that the chemical weathering index (K/Rb ratio) of Meihua Lake indicates the continuing effects of autumn rainfall, while coarse grain sizes of Dahu Lake sediments suggest increased intensity in typhoon rainfall. Grain size results reveal that increasing El Niño–Southern Oscillation intensity in the tropical Pacific has intensified the activity of super typhoons in the western North Pacific. Finally, we find that frequent activity of super paleo‐typhoons occurred in Taiwan during the La Niña‐like state, and the strengthening winter monsoon activity and higher sea surface temperature enhanced plentiful autumn rainfall in El Niño‐like state. After comparing our results with the paleo‐typhoon data in Japan and south China, we suggest that the tracks of super typhoon are mainly affected by variations in the warm pool and subtropical Northwestern Pacific High in the western Pacific. Copyright © 2012 John Wiley & Sons, Ltd.

Late Holocene environmental reconstructions and their implications on flood events, typhoon, and agricultural activities in NE Taiwan

“…Such spatial variations in precipitation reflect the regional climate characteristics, such as monsoonal precipitation or TC-triggered heavy rainfall. However, studies on the influences of TC intensity and frequency on local hydrology during the Holocene epoch are rare (Chen et al, 2012;Wang et al, 2013;Woodruff et al, 2009), even though the hydrological conditions, especially flooding, on the East Asian coast are strongly affected by TCs today.…”

“…1). It is an ideal area for a paleo-typhoon study, but very little investigation has been done so far, despite its importance (Chen et al, 2012). In addition, the interaction between human activity and environment is a topic in paleoecology.…”

“…Lanyang River is the main river on the plain, located to the south of DHL. A previous study addressed the high sedimentation rates of DHL as a consequence of massive inputs of suspended material from overflows from the Lanyang River at various time intervals during the middle to late Holocene (Chen et al, 2012). (Wolter and Timlin, 2011).…”

“…A 35 m sediment core (DH-7B) was taken and reached to the bottom by using a stainless corer on a floating platform in the western area of DHL in January, 2008 (Chen et al, 2012). The sediment core was stored at 4 • C in a dark room.…”

“…Linear interpolation of four radiocarbon dates reported by Chen et al (2012) and 210 Pb-derived sedimentation rate of the upper 23.5 cm were used to establish a revised age model of the core DH-7B (Fig. 3).…”