The research team aims to use quantitative wood anatomy to develop long high-resolution proxy records of past temperature from the Arctic North American tree-line and apply these to environmental reconstructions over the last millennium. The resulting high precision intra-annual information available from quantitative wood anatomy may aid researchers to specifically target seasonal windows of proxy climate sensitivity to better resolve both interannual climate variability and recent trends and precisely identify the timing of extreme events, including the cooling following volcanic eruptions. The array of seasonal information available from these records will be used within a data assimilation framework to produce enhanced climate field reconstructions of temperatures and associated atmospheric circulation fields over the last millennium for high latitude North America. The potential Broader Impacts include promoting the career of a female dendroclimatology doctoral student, engaging STEM K-12 teachers in fieldwork, thoughtful engagement with indigenous communities in the study region, and improved outreach materials at the Tree Ring lab in AZ. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.