Terrestrial carbon, water and energy fluxes measured by eddy covariance, and associated biomet variables, at three adjacent tundra ecosystems at Imnavait Creek, Alaska, 2023

This Arctic Observing Network (AON) project focuses on maintaining and expanding our long-term network of measurements of carbon, water, and energy exchange in terrestrial systems in Alaska. These exchanges help regulate the Arctic System and its feedbacks to global climate. Thus, extending long-term observations is a key science priority for the observing-change component of the Study of Environmental Arctic Change (SEARCH). Detecting and interpreting change in arctic carbon (C), water, and energy fluxes requires a continuous year-round record over multiple years. Recent data syntheses and modeling studies of Arctic Carbon balance suggest that tundra is either a carbon dioxide (CO2) sink, a source, or neutral (e.g., McGuire et al., 2009, McGuire et al., 2012) . This uncertainty arises mainly from a lack of data on winter CO2 flux and how tundra responds to recent warming. Because of harsh, remote environments and the lack of line power, long-term measurements of arctic CO2 fluxes over the full year are rare. We have been measuring year-round C, water, and energy fluxes for eleven years in two broadly representative flagship observatories with long-term histories of research, at Imnavait Creek near Toolik Lake, Alaska, and near Cherskiy, Siberia. Similar versions of these eddy covariance and biomet data are available from Ameriflux as sites US-ICx. https://ameriflux.lbl.gov/data/download-data/ Our three Imnavait Creek Alaska sites retained multiple names over the years. The following clarification is needed. The 'official' site name is followed by the technical station name (IC_xxxx), the positional name (Ridge), and the Ameriflux site name (US-ICx), and finally the site coordinates. Wet Sedge tundra (IC_1523, Fen, US-ICs) 68.6058 -149.3110 Tussock tundra (IC_1993, Tussock, US-ICt) 68.6063 -149.3041 Dry Heath tundra (IC_1991, Ridge, US-ICh) 68.6068 -149.2958北极观测网络（Arctic Observing Network, AON）项目旨在维护并拓展阿拉斯加陆地生态系统中碳、水与能量交换的长期监测网络。此类交换过程对北极系统及其对全球气候的反馈效应具有关键调节作用。因此，延续长期观测是北极环境变化研究（Study of Environmental Arctic Change, SEARCH）中“观测变化”分支的核心科学优先事项。 若要探测并解析北极碳（C）、水与能量通量的变化，需获取多年连续的全年观测记录。近期针对北极碳平衡的资料整合与模拟研究显示，苔原既可能为二氧化碳（CO₂）汇、源，也可能呈中性状态（如McGuire等，2009；McGuire等，2012）。这一不确定性主要源于冬季CO₂通量数据的缺失，以及对苔原如何响应近期气候变暖的认知不足。受北极恶劣偏远的环境条件限制，且缺乏市电供应，全年连续的北极CO₂通量长期监测数据极为稀缺。 我们已在两处具备长期研究历史、且具有广泛代表性的旗舰观测站，开展了长达11年的全年碳、水与能量通量监测：一处位于阿拉斯加图利克湖附近的伊姆纳韦特溪（Imnavait Creek），另一处位于西伯利亚切尔斯基（Cherskiy）附近。 上述涡度协方差（eddy covariance）与生物气象（biomet）数据的同类数据集，可从美国通量网（Ameriflux）的US-ICx站点获取，下载链接为：https://ameriflux.lbl.gov/data/download-data/ 我们位于阿拉斯加伊姆纳韦特溪的三个观测站点多年来曾使用多个名称，因此需作出如下澄清：各站点的正式命名依次对应技术站名（IC_xxxx）、位置名称、美国通量网站点名（US-ICx），最终附上站点坐标： - 湿薹草苔原（IC_1523，沼泽（Fen），US-ICs）：68.6058，-149.3110 - 草丘苔原（IC_1993，草丘（Tussock），US-ICt）：68.6063，-149.3041 - 干石楠苔原（IC_1991，山脊（Ridge），US-ICh）：68.6068，-149.2958