Robust observations of land-to-atmosphere feedbacks using the information flows of FLUXNET
Robust observations of land-to-atmosphere feedbacks using the information flows of FLUXNET
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DOI：
10.1038/s41612-019-0094-4
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发表时间：
2019-10-15
影响因子：
9
通讯作者：
Drewry, Darren T.
中科院分区：
文献类型：
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作者：
Gerken, Tobias;Ruddell, Benjamin L.;Drewry, Darren T.
大气过程（如降水和包括蒸散在内的陆面通量）之间的反馈很难观察，但对于理解陆面在地球系统中的作用至关重要。为了量化全球地表-大气反馈，我们使用应用于251个来自LaThuile数据库的涡度协方差站点的过程网络（PN）的结果来训练全球陆地表面的神经网络。温带地区夏季潜热通量（LE）和感热通量（H）与降水（P）之间存在较强的陆-气耦合，冬季潜热通量和感热通量与降水之间存在较强的陆-气耦合，而热带雨林的陆-气耦合季节性较弱。稀树草原、灌丛和其他半干旱生态系统在其耦合行为中表现出强烈的响应。反馈耦合从表面通量P峰值干旱（P/潜在蒸散ETP）值附近的团结，而耦合相对于云，推断减少全球辐射，增加P/ETP接近零。反馈耦合强度的空间格局与气候带和生物群落类型有关。信息流统计突出了以下热点：（1）撒哈拉以南非洲的持续陆-气耦合;（2）美国中部和西南部、巴西和刚果盆地的北方夏季耦合;（3）南部安第斯山脉、南非和澳大利亚的南方夏季耦合。我们利用全球FLUXNET数据库和信息流统计的数据驱动的方法来量化陆地大气耦合强度，为验证大气环流模型中的反馈相互作用和预测土地覆盖变化将反馈到气候或天气的位置提供了基础。
Feedbacks between atmospheric processes like precipitation and land surface fluxes including evapotranspiration are difficult to observe, but critical for understanding the role of the land surface in the Earth System. To quantify global surface-atmosphere feedbacks we use results of a process network (PN) applied to 251 eddy covariance sites from the LaThuile database to train a neural network across the global terrestrial surface. There is a strong land-atmosphere coupling between latent (LE) and sensible heat flux (H) and precipitation (P) during summer months in temperate regions, and between H and P during winter, whereas tropical rainforests show little coupling seasonality. Savanna, shrubland, and other semi-arid ecosystems exhibit strong responses in their coupling behavior based on water availability. Feedback couplings from surface fluxes to P peaks at aridity (P/potential evapotranspiration ETp) values near unity, whereas coupling with respect to clouds, inferred from reduced global radiation, increases as P/ETp approaches zero. Spatial patterns in feedback coupling strength are related to climatic zone and biome type. Information flow statistics highlight hotspots of (1) persistent land-atmosphere coupling in sub-Saharan Africa, (2) boreal summer coupling in the central and southwestern US, Brazil, and the Congo basin and (3) in the southern Andes, South Africa and Australia during austral summer. Our data-driven approach to quantifying land atmosphere coupling strength that leverages the global FLUXNET database and information flow statistics provides a basis for verification of feedback interactions in general circulation models and for predicting locations where land cover change will feedback to climate or weather.