NOAA/WDS Paleoclimatology - Pearl - Orleans Swamp - CHTH - ITRDB MA032

High-resolution paleoclimate records are essential for improving our understanding of internal variability and the detection and attribution of forced climate system responses. The densely populated northeastern United States is at risk from increasing temperatures, severe droughts, and extreme precipitation, but the region has limited annual and seasonal-resolution paleoclimate records beyond the instrumental record. Chamaecyparis thyoides, L. (B.S.P.), Atlantic white cedar, a wetland conifer found within 200 km of the Atlantic coastline of the United States, is a promising tree-ring proxy that can fill in these data gaps. Here, we develop and analyze a new network of Atlantic white cedar tree-ring chronologies across the northeastern United States and demonstrate that site selection is important for regional paleoclimate reconstructions. Ring width variability reflects winter through summer temperatures at inland and hydrologically stable sites in the northernmost section of the species' range. Ombrotrophic sites along the coast record hydrological signals and correlate with growing season precipitation. We demonstrate skillful regional climate field reconstructions for the last several centuries and show the increased skill from incorporating our moisture sensitive sites into broad-scale products like the North American Drought Atlas. This comprehensive understanding of the species' climate responses leads to a tree-ring network that provides the long-term multivariate climate context at multidecadal and centennial time scales for the large-scale ocean-atmospheric processes that influence the climate of the region. We use this network to examine the covariance of temperature and drought across the New England area over the past two centuries.

高分辨率古气候记录（paleoclimate records）对于深化我们对气候系统内部变率的认知，以及对强迫驱动的气候系统响应开展检测与归因研究至关重要。人口稠密的美国东北部地区正面临气温升高、严重干旱与极端降水加剧的风险，但该区域除器测记录外，兼具年际与季节分辨率的古气候记录极为匮乏。大西洋白雪松（Chamaecyparis thyoides (L.) B.S.P.）是一种生长于美国大西洋沿岸200公里范围内的湿地针叶树种，作为极具潜力的树轮代用指标（tree-ring proxy），可填补上述数据空白。本研究在美国东北部区域构建并分析了一套全新的大西洋白雪松树轮年表网络，证实样点选择对于区域古气候重建工作至关重要。在该物种分布最北界的内陆且水文稳定的样点中，轮宽变化可反映冬夏季气温状况；沿海沿岸的雨养沼泽样点则可记录水文信号，并与生长季降水显著相关。本研究证实可对过去数百年开展高精度区域气候场重建，并表明将对水分敏感的样点纳入北美干旱图集（North American Drought Atlas）这类大尺度气候产品中，可提升重建精度与可靠性。通过对该物种气候响应机制的全面解析，本研究构建的树轮网络可为影响该区域气候的大尺度海气过程，提供数十年至百年尺度的长期多变量气候背景。本研究利用该树轮网络，探究了过去两个世纪新英格兰区域的气温与干旱协变特征。