Radiocarbon in tropical tree rings during the Little Ice Age

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Vol. 223-224; pp. 489 - 494
• Main Authors: Hua, Q, Barbetti, M, Zoppi, U, Fink, D, Watanasak, M, Jacobsen, G.E
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2004
• Subjects: Asian monsoon; Atmospheric transport; ITCZ; Little Ice Age; Radiocarbon; Solar activity; Tree-rings; ITCZ; Solar activity; Radiocarbon; Tree-rings; Atmospheric transport; 91.10.Vr; Little Ice Age; 92.60.Bh; Asian monsoon
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/j.nimb.2004.04.092

Cross-dated tree-ring cores (Pinus merkusii) from north-central Thailand, spanning AD 1620–1780, were used to investigate atmospheric 14C for the tropics during the latter part of the Little Ice Age. In addition, a cross-dated section of Huon pine from western Tasmania, covering the same period of time, was investigated. A total of 16 pairs of decadal samples were extracted to alpha-cellulose for AMS 14C analysis using the ANTARES facility at ANSTO. The 14C results from Thailand follow the trend of the southern hemisphere, rather than that of the northern hemisphere. This is a surprising result, and we infer that atmospheric 14C for north-central Thailand, at 17° N, was strongly influenced by the entrainment of southern hemisphere air parcels during the southwest Asian monsoon, when the Inter-Tropical Convergence Zone moves to the north of our sampling site. Such atmospheric transport and mixing are therefore considered to be one of the principal mechanisms for regional 14C offsets.