Strong Correspondence in Evapotranspiration and Carbon Dioxide Fluxes Between Different Eddy Covariance Systems Enables Quantification of Landscape Heterogeneity in Dryland Fluxes
Strong Correspondence in Evapotranspiration and Carbon Dioxide Fluxes Between Different Eddy Covariance Systems Enables Quantification of Landscape Heterogeneity in Dryland Fluxes
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DOI：
10.1029/2021jg006240
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发表时间：
2022-08-01
影响因子：
3.7
通讯作者：
Hill, Timothy C.
中科院分区：
文献类型：
--
作者：
Cunliffe, Andrew M.;Boschetti, Fabio;Hill, Timothy C.
涡度相关方法被广泛用于研究景观尺度的能量、水和二氧化碳通量，为生态系统的功能提供重要信息。通量测量量化了生态系统对环境扰动和管理战略的反应，包括基于自然的气候变化减缓措施。然而，由于传统仪器的高成本，大多数涡度协方差研究采用一个单一的系统，限制了空间表示的通量足迹。不充分的复制可能会限制我们对生态系统行为的理解。为了解决这个问题，我们部署了8个低成本的涡度协方差系统在两个集群周围的两个传统的涡度协方差系统在北美奇瓦瓦沙漠为期2年。这些旱地环境的特点是温度变化大，二氧化碳通量相对较低，这对涡度协方差来说是一个挑战。我们发现所有系统的能量和水平衡都非常好（在+/- 9%的范围内）。我们发现低成本和传统系统的感热通量（一致性相关系数（CCC）>= 0.87），潜热（蒸散; CCC >= 0.89），以及在净生态系统交换有用的对应关系（（NEE）; CCC >= 0.4）在日常的时间分辨率之间有很好的对应关系。相对于传统的系统，低频系统的特点是更高水平的随机误差，特别是在NEE通量。较低成本的系统可以使更广泛的部署，提供更好的复制和采样的时空变化的代价是更大的测量噪声，可能会限制某些应用程序。重复涡度协方差观测可能有助于弥补现有对关键和代表性不足的生态系统的监测方面的空白，并有助于测量大于单一通量足迹的区域。
The eddy covariance method is widely used to investigate fluxes of energy, water, and carbon dioxide at landscape scales, providing important information on how ecological systems function. Flux measurements quantify ecosystem responses to environmental perturbations and management strategies, including nature-based climate-change mitigation measures. However, due to the high cost of conventional instrumentation, most eddy covariance studies employ a single system, limiting spatial representation to the flux footprint. Insufficient replication may be limiting our understanding of ecosystem behavior. To address this limitation, we deployed eight lower-cost eddy covariance systems in two clusters around two conventional eddy covariance systems in the Chihuahuan Desert of North America for a period of 2 years. These dryland settings characterized by large temperature variations and relatively low carbon dioxide fluxes represented a challenging setting for eddy covariance. We found very good closure of energy and water balance across all systems (within +/- 9% of unity). We found very good correspondence between the lower-cost and conventional systems' fluxes of sensible heat (with concordance correlation coefficient (CCC) of >= 0.87), latent energy (evapotranspiration; CCC >= 0.89), and useful correspondence in the net ecosystem exchange ((NEE); with CCC >= 0.4) at the daily temporal resolution. Relative to the conventional systems, the low-frequency systems were characterized by a higher level of random error, particularly in the NEE fluxes. Lower-cost systems can enable wider deployment affording better replication and sampling of spatiotemporal variability at the expense of greater measurement noise that might be limiting for certain applications. Replicated eddy covariance observations may be useful when addressing gaps in the existing monitoring of critical and underrepresented ecosystems and for measuring areas larger than a single flux footprint.