Across temperate North America, interannual variability (IAV) in gross primary production (GPP) and net ecosystem exchange (NEE) and their relationship with environmental drivers are poorly understood. Here, we examine IAV in GPP and NEE and their relationship to environmental drivers using two state‐of‐the‐science flux products: NEE constrained by surface and space‐based atmospheric CO2 measurements over 2010–2015 and satellite up‐scaled GPP from FluxSat over 2001–2017. We show that the arid western half of temperate North America provides a larger contribution to IAV in GPP (104% of east) and NEE (127% of east) than the eastern half, in spite of smaller magnitude of annual mean GPP and NEE. This occurs because anomalies in western ecosystems are temporally coherent across the growing season leading to an amplification of GPP and NEE. In contrast, IAV in GPP and NEE in eastern ecosystems is dominated by seasonal compensation effects, associated with opposite responses to temperature anomalies in spring and summer. Terrestrial biosphere models in the MsTMIP ensemble generally capture these differences between eastern and western temperate North America, although there is considerable spread between models.

中文翻译：

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对比北美温带东西分界对季节性气候异常的区域碳循环响应

在北美温带地区，初级生产总值 (GPP) 和净生态系统交换 (NEE) 的年际变化 (IAV) 及其与环境驱动因素的关系知之甚少。在这里，我们使用两种最科学的通量产品来检查 GPP 和 NEE 中的 IAV 及其与环境驱动因素的关系：NEE 受 2010-2015 年地表和天基大气 CO2 测量的约束，以及来自 FluxSat 的卫星放大 GPP 2001-2017 年。我们表明，尽管年平均 GPP 和 NEE 的幅度较小，但与东半部相比，温带北美洲干旱的西半部对 GPP（东部的 104%）和 NEE（东部的 127%）的 IAV 贡献更大。这是因为西方生态系统的异常在整个生长季节在时间上是一致的，导致 GPP 和 NEE 放大。相比之下，东部生态系统中 GPP 和 NEE 中的 IAV 以季节性补偿效应为主，与春季和夏季温度异常的相反响应相关。MsTMIP 集合中的陆地生物圈模型通常捕捉到北美东部和西部温带之间的这些差异，尽管模型之间存在相当大的差异。