Investigating the mechanisms responsible for the lack of surface energy balance closure in a central Amazonian tropical rainforest
Investigating the mechanisms responsible for the lack of surface energy balance closure in a central Amazonian tropical rainforest
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DOI：
10.1016/j.agrformet.2017.03.023
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发表时间：
2018-05-28
影响因子：
6.2
通讯作者：
Stoy, Paul C.
中科院分区：
文献类型：
--
作者：
Gerken, Tobias;Ruddell, Benjamin L.;Stoy, Paul C.
这项工作调查的能量平衡残差（E）的昼夜和季节行为，结果从可用能量和湍流通量的显热（H）和潜热（LE）在FLUXNET BR-Ma 2网站位于巴西亚马逊热带雨林中心之间的观测差异。通过将涡度协方差平均长度从30分钟延长到4小时，并通过应用信息流动态过程网络来诊断不同季节影响E的过程和条件，分析了E的行为。结果表明，季节性湍流通量动力学和波文比主要由净辐射（Rn）驱动，具有显著的亚季节变化。鲍文比率从4月份的0.25上升至9月底的0.4。平均长度从0.5（94.6%闭合）延长到4 h，从而包含更长时间尺度的涡旋和中尺度过程，关闭了能量平衡，导致Bowen比增加，从而突出了额外H到E的重要性。信息流分析表明，能量平衡的组成部分解释了25%和40%之间的总香农熵较高的值在雨季比旱季。从浮力通量到E的旱季信息流比从H到E的旱季信息流大30-50%，表明浮力通量对关闭E的潜在重要性。虽然低封闭突出了额外的来源没有捕获的通量数据和随机测量误差，有助于E，信息流和平均长度分析的结果是一致的中尺度环流的影响，这往往会运输更多的H比LE，关闭的缺乏。
This work investigates the diurnal and seasonal behavior of the energy balance residual (E) that results from the observed difference between available energy and the turbulent fluxes of sensible heat (H) and latent heat (LE) at the FLUXNET BR-Ma2 site located in the Brazilian central Amazon rainforest. The behavior of E is analyzed by extending the eddy covariance averaging length from 30 min to 4 h and by applying an Information Flow Dynamical Process Network to diagnose processes and conditions affecting E across different seasons. Results show that the seasonal turbulent flux dynamics and the Bowen ratio are primarily driven by net radiation (R-n), with substantial sub-seasonal variability. The Bowen ratio increased from 0.25 in April to 0.4 at the end of September. Extension of the averaging length from 0.5 (94.6% closure) to 4 h and thus inclusion of longer timescale eddies and mesoscale processes closes the energy balance and lead to an increase in the Bowen ratio, thus highlighting the importance of additional H to E. Information flow analysis reveals that the components of the energy balance explain between 25 and 40% of the total Shannon entropy with higher values during the wet season than the dry season. Dry season information flow from the buoyancy flux to E are 30-50% larger than that from H, indicating the potential importance of buoyancy fluxes to closing E. While the low closure highlights additional sources not captured in the flux data and random measurement errors contributing to E, the findings of the information flow and averaging length analysis are consistent with the impact of mesoscale circulations, which tend to transport more H than LE, on the lack of closure.