Accurate estimation of the surface-emitted longwave radiation (SELR) has important scientific value in understanding its spatiotemporal dynamics and surface thermal environment. Thermal infrared (TIR) images with high spatial resolution offer enhanced data support for studying SELR of complex surfaces, such as urban surface. This study proposes a new urban-oriented hybrid (UoHy) method, which considers multiple scattering and adjacent effects of urban pixel using the term sky view factor, to estimate urban SELR from the top-of-atmosphere radiance of TIR images with high spatial resolution, and performs sensitivity analysis and application. The experimental results for the thermal images of GF-5/VIMS as an example showed that the UoHy method has relatively high accuracy, and obtains SELR errors of less than 12.0 W/m² under low atmospheric water vapor conditions and less than 17.0 W/m² under high atmospheric water vapor conditions. The application of the method during daytime and nighttime also demonstrated the method's validity and effectiveness. Compared with the natural surface-oriented hybrid method, the UoHy method obtains an improvement of about 7.0–10.0 W/m² in SELR estimation, which indicates that it has the potential for practical SELR estimation over urban surface with TIR images of high spatial resolution.

中文翻译：

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基于混合方法的高空间分辨率热红外图像的城市地表发射长波辐射估计


准确估计表面发射长波辐射 （SELR） 对于理解其时空动力学和表面热环境具有重要的科学价值。具有高空间分辨率的热红外 （TIR） 图像为研究复杂表面（如城市表面）的 SELR 提供了增强的数据支持。本研究提出了一种新的面向城市的混合 （UoHy） 方法，该方法使用术语天空视角因子考虑城市像素的多重散射和相邻效应，从高空间分辨率 TIR 图像的大气顶部辐射估计城市 SELR，并进行灵敏度分析和应用。以 GF-5/VIMS 的热像为例的实验结果表明，UoHy 方法具有较高的精度，在低大气水蒸气条件下获得小于 12.0 W/m² 的 SELR 误差，在高大气水蒸气条件下获得小于 17.0 W/m² 的 SELR 误差。该方法在白天和夜间的应用也证明了该方法的有效性和有效性。与自然表面定向混合方法相比，UoHy 方法在 SELR 估计方面获得了约 7.0–10.0 W/m² 的改进，这表明它具有在城市表面使用高空间分辨率的 TIR 图像进行实际 SELR 估计的潜力。