The First Tree-Ring Blue Intensity Measurements from the Korean Peninsula: Exploring Summer Temperature Signals

Tree-ring blue intensity (BI), a proxy measuring blue light reflection from tree-ring cores, has emerged as a promising tool for climate reconstruction, yet its application in East Asia remains limited. Here we evaluate the dendroclimatological potential of tree-ring blue intensity using Korean pine (Pinus koraiensis Siebold & Zucc.) samples from Mt. Seorak in the Korean Peninsula. We developed chronologies using tree-ring width (TRW) and three BI parameters (earlywood BI, maximum latewood BI, and delta BI), with delta BI (DBI) exhibiting robust correlations with summer (July-August) mean surface air temperature (SAT). Despite weak series intercorrelation in the BI chronologies, the DBI measurements preserved consistent temperature signals from the early 20th century to present, in contrast to the inconsitent climate response in the TRW data. The DBI chronology further demonstrated potential for reconstructing large-scale atmospheric patterns, including the circumglobal teleconnection pattern and subtropical jet stream. Our findings establish BI methodology as a valuable tool for enhancing climate reconstructions in subtropical East Asia, particularly in regions where traditional TRW measurements prove inadequate for capturing summer temperature signals.