Estimation of Surface Upward Longwave Radiation Using a Direct Physical Algorithm

作者：Tian Hu, Biao Cao, Yongming Du, Hua Li, Cong Wang, Zunjian Bian, Donglian Sun, Qinhuo Liu · 发表于：IEEE Transactions on Geoscience and Remote Sensing · 年份：2017 · DOI：10.1109/tgrs.2017.2692261 · 被引用次数：35 · 研究领域：Urban Heat Island Mitigation、Soil Moisture and Remote Sensing、Cryospheric studies and observations

Surface upward longwave radiation (SULR) is a significant component of the surface radiation budget and is closely linked with evapotranspiration, soil moisture, and surface cooling on clear nights. Therefore, accurately estimating SULR is essential to better understand its spatiotemporal dynamics or to characterize the thermal environment of a given land surface. Currently, most methods for estimating SULR (including the physical and hybrid methods) fail to account for the thermal anisotropy, which can introduce significant errors into the calculation. We previously proposed the combined algorithm that considers the thermal anisotropy to more accurately estimate the SULR. However, this proposed method has several shortcomings. For example, it considers the directionality of the emissivity and the effective temperature separately under the support of a parametric directional emissivity model. However, the directional emissivity model is not maturely developed for different land surface types, especially on non-vegetated surfaces. And the separation of land surface temperature and emissivity may undermine the estimation accuracy. Furthermore, this proposed method requires a series of input parameters that is not always available, limiting its applicability. In this paper, we present a refined algorithm that uses a kernel-driven model and the technique of band conversion to calculate the SULR directly based on surface-leaving radiances. This direct physical algorithm is then ap...