Experimental closure of the surface energy balance during convective periods is a long-standing problem. With experimental data from the Idealized horizontal Planar Array experiment for Quantifying Surface heterogeneity, the terms of the temperature-tendency equation are computed, with an emphasis on the total derivative. The experiment occurred at the Surface Layer Turbulence and Environmental Science Test facility at the U.S. Army Dugway Proving Ground during the summer of 2019. The experimental layout contained an array of 21 flux stations over a 1 km\(^2\) grid. Sensible heat fluxes show high spatial variability, with maximum variability occurring during convective periods. Maximum variability in the vertical heat flux is 50–80 W m\(^{-2}\) (median variability of 40%), while in the horizontal flux, it is 200–500 W m\(^{-2}\) (median variability of 48% for the streamwise and 40% for the spanwise fluxes). Ensemble averages computed during convective afternoon periods show large magnitudes of horizontal advection (48 W m\(^{-3}\) or 172 K h\(^{-1}\)) and vertical flux divergence (13 W m\(^{-3}\) or 47 K h\(^{-1}\)). Probability density functions of the total derivative from convective cases show mean volumetric heating rates of 43 W m\(^{-3}\) (154 K h\(^{-1}\)) compared to 13 W m\(^{-3}\) (47 K h\(^{-1}\)) on non-convective days. A conceptual model based on persistent mean flow structures from local-surface-temperature heterogeneities may explain the observed advection. The model describes the difference between locally-driven advection and advection driven by larger-scale forcings. Of the cases examined, 83% with streamwise and 81% with spanwise advection during unstable periods are classified as locally driven by nearby surface thermal heterogeneities.

对流期间实验性关闭表面能平衡是一个长期存在的问题。利用理想化水平平面阵列实验中用于量化表面异质性的实验数据，计算温度趋势方程的项，重点是总导数。该实验于2019年夏季在美国陆军Dugway试验场的表面层湍流和环境科学测试设施中进行。实验布局包含1公里2（^ 2 \）网格上的21个通量站组成的阵列。感热通量显示出高的空间变异性，在对流期间会出现最大的变异性。垂直热通量的最大变化为50–80 W m \（^ {-2} \）（中值变异性为40％），而在水平通量中为200–500 W m \（^ {-2} \）（流向中值变异性为48％，跨度通量中值变异性为40％）。对流下午期间计算的集合平均数显示出水平对流（48 W m \（^ {-3} \）或172 K h \（^ {-1} \））和垂直通量发散（13 W m \（ ^ {-3} \）或47 K h \（^ {-1} \））。对流情况下总导数的概率密度函数显示平均体积加热率为43 W m \（^ {-3} \）（154 K h \（^ {-1} \））而13 W m \（^ {-3} \）（47 K h \（^ {-1} \））。基于局部表面温度异质性的持久平均流结构的概念模型可以解释观测到的对流。该模型描述了局部驱动的对流与大规模强迫驱动的对流之间的区别。在所考察的情况中，在不稳定时期，沿流向平流的比例为83％，沿对流平流的比例为81％，被归类为由附近表面热非均质性局部驱动。