Spatial and temporal patterns of surface-atmosphere energy exchange in a dense urban environment using scintillometry
Spatial and temporal patterns of surface-atmosphere energy exchange in a dense urban environment using scintillometry
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DOI：
10.1002/qj.2967
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发表时间：
2017-01-01
影响因子：
8.9
通讯作者：
Kotthaus, S.
中科院分区：
文献类型：
--
作者：
Crawford, B.;Grimmond, C. S. B.;Kotthaus, S.
在城市地区，需要对地表能量平衡（SEB）进行空间综合测量，以评估城市气候模式和卫星观测结果。闪烁仪允许观测的显热通量（Q（H））超过更大的区域比技术，如涡度协方差（EC），但需要的方法来分割之间的剩余未测量SEB条款。这是第一个研究使用观测到的空间和时间模式的Q（H）从一个密集的，异构的城市环境中，以约束估计剩余的SEB条款。结果表明，Q（H）占主导地位的表面能量平衡在中心伦敦全年，与预期的日进程和季节变化趋势的Q（H）的大小有关的太阳辐射输入。测量还揭示了一个明确的人为因素的Q（H）与冬季（夏季）工作日Q（H）值比周末高11.7%（5.1%）。在空间上，Q（H）大小与测量源区域的植被和建筑物土地覆盖率相关。空间分析提供了额外的证据，人类活动的影响与最高的工作日/周末的比率（1.55），从伦敦市。空间差异被用来估计水平平流和一个新的方法来估计月潜热通量的基础上观测到的土地覆盖和干湿表面变化的归一化Q（H）。利用能量平衡残差法估算的年人为热排放量为46.3Wm（-2）。这里提出的方法有可能显着提高对城市地区的理解，特别是在高层建筑的地区，那里几乎没有观测数据。
Spatially integratedmeasurements of the surface energy balance (SEB) are needed in urban areas to evaluate urban climate models and satellite observations. Scintillometers allow observations of sensible heat flux (Q(H)) overmuch larger areas than techniques such as eddy covariance (EC), however methods are needed to partition between remaining unmeasured SEB terms. This is the first study to use observed spatial and temporal patterns of Q(H) from a scintillometer network to constrain estimates of remaining SEB terms in a dense, heterogeneous urban environment. Results show that Q(H) dominates the surface energy balance in central London throughout the year, with expected diurnal courses and seasonal trends in Q(H) magnitude related to solar radiation input. Measurements also reveal a clear anthropogenic component of Q(H) with winter (summer) weekday Q(H) values 11.7% (5.1%) higher than weekends. Spatially, Q(H) magnitude is correlated with vegetation and building landcover fraction in the measurement source areas. Spatial analysis provides additional evidence of anthropogenic influence with highest weekday/weekend ratios (1.55) from the City of London. Spatial differences are used to estimate horizontal advection and a novel method to estimate monthly latent heat flux is developed based on observed landcover and wet-dry surface variations in normalized Q(H). Annual anthropogenic heat emissions are estimated to be 46.3Wm(-2) using an energy balance residual approach. The methods presented here have potential to significantly enhance understanding of urban areas, particularly in areas with tall buildings where there are few observational data.