August-September maximum temperature reconstruction for the Southeastern United States (1760-2022 CE)

Over recent decades, the southeastern United States (Southeast) has become increasingly well represented by the terrestrial climate proxy record. However, while the paleo proxy records capture the region’s hydroclimatic history over the last several centuries, the understanding of near-surface air temperature variability is confined to the comparatively shorter observational period (1895-present). Here, we detail the application of blue intensity (BI) methods on a network of tree-ring collections and examine their utility for producing robust paleotemperature estimates. Results indicate that maximum latewood BI (LWBI) chronologies exhibit positive and temporally stable correlations (r = 0.28- 0.54, p < 0.01) with summer maximum temperatures. As such, we use a network of LWBI chronologies to reconstruct the August-September average maximum temperatures for the Southeast spanning the period 1760-2010 CE. Our work demonstrates the utility of applying novel dendrochronological techniques to improve the understanding of the longer-term temperature history of the Southeast.近数十年来，美国东南部（Southeast）的陆地气候代用记录（terrestrial climate proxy record）愈发完备。尽管古气候代用记录（paleo proxy records）已重建了该区域近数个世纪的水文气候历史，但学界对近地表气温变率的认知仍局限于相对较短的观测时段（1895年至今）。本文详述了蓝强度（blue intensity, BI）方法在树木年轮序列（tree-ring collections）网络中的应用，并检验了其用于构建稳健古温度估算（paleotemperature estimates）结果的可行性。研究结果显示，晚材蓝强度（latewood blue intensity, LWBI）年表（chronologies）与夏季最高气温呈现显著且时间稳定的正相关关系（相关系数r=0.28~0.54，p<0.01）。据此，我们利用晚材蓝强度年表网络重建了公元1760年至2010年期间美国东南部的8-9月平均最高气温序列。本研究证实了运用新兴树木年代学（dendrochronological）技术，可增进对美国东南部长期气温历史的认知。