A 30 Ka Summer Monsoon Driven Terrestrial Rainfall Variability Record From Central Highlands of Sri Lanka

An overview of Holocene monsoon variability of Sri Lanka and its association with Indian subcontinent climate records

“…A sedimentary record from the western continental shelf revealed a low terrestrial influx from 4.0 kyr BP to 2.0 kyr BP, indicating a decreased intensity of southwest monsoon precipitation. However, the monsoon winds were stronger during this period as depicted by upwelling proxies (Ranasinghe et al, 2016).…”

“…Based on upwelling and terrestrial proxies, enhanced southwest monsoon activity during the early Holocene (10.0-8.0 kyr BP) was also detected in a marine record from the western continental shelf off Colombo (Ranasinghe et al, 2017). After the 12.5 kyr BP Younger Dryas cold event, wet and warm conditions were gradually increased and depicts an early Holocene summer monsoon strengthening as evident in LOI, TOC, TN, δ 13 C, δ 15 N, major and trace element ratios, and diffuse color reflectance proxies in sediment records from Gawaratenna Plateau (Ranasinghe et al, 2017). However, monsoon strength has weakened at around 8.2 kyr BP, showing a teleconnection with North Atlantic cold episodes.…”

“…Similarly, wet or dry monsoon climate can be identified based on the dominance of each taxon of siliceous microfossil types within a specific period (Premathilake, 2006;Misra and Bhattacharyya, 2014;Veena et al, 2014). Based on upwelling and terrestrial proxies, enhanced southwest monsoon activity during the early Holocene (10.0-8.0 kyr BP) was also detected in a marine record from the western continental shelf off Colombo (Ranasinghe et al, 2017). After the 12.5 kyr BP Younger Dryas cold event, wet and warm conditions were gradually increased and depicts an early Holocene summer monsoon strengthening as evident in LOI, TOC, TN, δ 13 C, δ 15 N, major and trace element ratios, and diffuse color reflectance proxies in sediment records from Gawaratenna Plateau (Ranasinghe et al, 2017).…”

“…Signs of fading monsoons were also detected during the period of 2.4-2.0 kyr BP (Gayantha et al, 2019b) and 2.0 kyr BP to present (Premathilake and Risberg, 2003) in the south-west monsoon. A sediment core from the central highland also indicated a dry period from 4.0 to 1.0 kyr BP (Ranasinghe et al, 2017). Depicting the highly dynamic nature of the late Holocene summer monsoon, the periods extending from 1.78 to 1.29 kyr BP and 1.0 kyr BP to present were recorded as active monsoon phases (Ambillapitiya et al, 2017;Gayantha et al, 2017).…”