Obtaining accurate estimates of surface-atmosphere energy exchanges and improved comprehension of the mechanisms generating turbulent fluxes over non-uniform landscapes are both challenging goals and essential for validating numerical weather forecasting modeling. In this work, a large-aperture scintillometer (LAS) was deployed to evaluate the effect of mesoscale sea and valley breezes with respect to diurnal sensible heat flux (H) variability over an urban area close to a coastal bay near the metropolitan area of Rio de Janeiro (MARJ) during the austral summer of 2017–2018 time span. The region is characterized by a densely urbanized environment, surrounded by mountainous relief and bounded by a large ocean bay. The transmitter and the receiver of the LAS system were installed 1955 m apart. Diurnal cycle was divided into four periods according to the local time: dawn (00 a.m. to 6 a.m.), morning (6 a.m. to 12 a.m.), afternoon (12 a.m. to 6 p.m.), and night (6 p.m. to 00 a.m.). The results demonstrated the sensitivity of the LAS to record variations in H over the course of the day, taking into account the corresponding sea and valley breezes and the relative humidity variability. During the morning, when valley breezes are predominant, footprint area shrinks to its smallest size, encompassing an area of approximately 2 km². On the other side, during afternoon and night time periods, during afternoon and night time periods, the presence of sea breeze jointly with a densely urbanized continental area contribute to promote significant changes in the footprint area ranging from 2.05 to 5.38 km². The effects of topography are also well captured in the diurnal H cycle once sunset and corresponding shading in the late afternoon abruptly reduces heat-sensible flux. Diurnal variations in footprint shape and area lead to modifications in terms of the mode each type of urban surface will contribute to H, increasing the influence of anthropogenic elements in afternoon and early evening. Complementarily, it is noteworthy to mention that a sensitivity test was performed to assess uncertainties in H estimates for the free convection method, which requires the estimation of an empirical constant b. Variations in this constant introduce larger dispersion in H estimates than potential errors in LAS effective height (Z_eff) estimations or temperature measurements. These last results highlight the importance of conducting further evaluations as the one pursued in this study to more rigorously validate the outputs of numerical mesoscale and local hydrometeorological models and remotely sensed products.

获得对地表大气能量交换的准确估计和对在非均匀景观上产生湍流通量的机制的更好理解，既是具有挑战性的目标，也是验证数值天气预报模型的必要条件。在这项工作中，部署了大孔径闪烁仪 (LAS) 来评估中尺度海风和山谷风对昼夜感热通量 ( H) 在 2017 年至 2018 年的南方夏季期间，靠近里约热内卢大都市区 (MARJ) 附近沿海海湾的城市地区的变化。该地区的特点是城市化环境密集，周围环绕着山地起伏，并以大湾为界。LAS 系统的发射器和接收器的安装距离为 1955 m。昼夜循环按当地时间分为四个时段：黎明（00am-6am）、早晨（6am-12am）、下午（12am-6pm）和夜间（6pm-00am）。结果表明 LAS 对记录H在一天的过程中，考虑到相应的海风和山谷微风以及相对湿度的变化。早晨，当山谷微风占主导地位时，足迹面积缩小到最小，包括大约 2 km ²的面积。另一方面，在下午和夜间时段，在下午和夜间时段，海风的存在以及密集的城市化大陆区域有助于促进足迹面积从 2.05 到 5.38 km ^{2 的}显着变化。在昼夜H中也很好地捕捉了地形的影响一旦日落和相应的阴影在下午晚些时候循环会突然减少热敏通量。足迹形状和面积的日变化导致每种类型的城市表面对H 的贡献模式发生变化，从而增加了下午和傍晚人为因素的影响。另外，值得注意的是，进行了敏感性测试以评估自由对流方法的H估计值的不确定性，这需要估计经验常数b。在这个恒定变化引入较大的分散ħ估计比LAS有效高度潜在的错误（ž _EFF) 估计或温度测量。这些最后的结果强调了进行进一步评估的重要性，正如本研究所追求的那样，以更严格地验证数值中尺度和局部水文气象模型以及遥感产品的输出。