The overarching goal of the project is to understand tundra ecosystem change across landscape types and enable realistic forecasts of change across the Arctic. The power of the International Tundra Experiment (ITEX)- Arctic Observatory Network (AON) is founded on a capacity to synthesize and compare results across sites that use standardized sampling protocols. Specifically, this project will (1) maintain the data-streams at ITEX-AON sites in Alaska near Toolik Lake, Imnavait Creek, Utqiagvik (Barrow), and Atqasuk; (2) lead two new ITEX network syntheses focused on soil carbon and phenocam imagery; (3) increase scientific literacy; and, (4) expand citizen science opportunities across communities in northern Alaska. The project will sustain an array of large and publicly available data-streams documenting ecosystem change occurring across the Arctic and will team up with citizen scientists to expand the monitoring footprint of the network and the societal relevance of this work to communities across the North Slope of Alaska. The ITEX network was chartered in 1990 to document and understand the ecological impacts of a warming Arctic. The US-led ITEX projects expanded their monitoring efforts across a larger spatial area with the use of automated sampling to form an Arctic Observatory Network (AON) in 2009. The ITEX-AON currently includes traditional ITEX measurements (phenology, cover, carbon flux and nutrient cycling), as well as phenocams, automated mobile sensor platforms (MISP) and mid-scale aerial imagery of 1 km2 ARCSS (Arctic System Science) grids established in the 1990s. In this phase of the project, collection of core data sets will be sustained and new data sets will be added with the aim of identifying and understanding patterns of change and feedbacks. Specifically, ITEX-AON will expand its collection of vegetation functional traits to better understand ecosystem response and predict future change. ITEX-AON will also further expand automated measurements to link plot level change (sampled by hand or with hand-held equipment) with landscape level observations (sampled by phenocams or drones) and high resolution regional imagery (sampled by aircraft or satellite). The new phase of ITEX-AON will include two synthesis efforts: (1) an examination of soil carbon dynamics across the ITEX network, and (2) a multi-scale phenological analysis using phenocam and high resolution satellite imagery to determine fine-scale spatiotemporal patterns of seasonal greening trends across the Arctic. Mentoring of postdocs, and training of graduate and undergraduate students are some of the primary broader impacts of this project. The project will continue to provide a test bed for engineering and software development that will be shared freely among the ITEX network and broader science community and will expand outreach activities aimed at improving science literacy.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.