The Use and Potential of Far-Infrared Remote Sensing in Deriving Surface Longwave Downward Radiation under Clear-Sky Conditions
Utilisation et potentiel de la télédétection infrarouge lointain pour la détermination du rayonnement descendant de grande longueur d'onde en surface par ciel clair
Du, Yihan ; Wang, Tianxing ; Li, Dahui ; Zheng, Yi ; Xian, Yuyang ; Buehler, Stefan A.
Année de publication
2025
Surface longwave downward radiation (LWDR) is an essential parameter in Earth's radiation balance and climate change studies. To date, almost all existing space-based LWDR studies mainly focus on the traditional thermal infrared (TIR) spectrum of 4-15 ?m. The far-infrared (FIR) spectrum (>15 ?m), with its high sensitivity to temperature and water vapor, has the potential to greatly improve the derivation accuracy of LWDR, which is closely related to the above variables. This study proposes a novel attempt to estimate clear-sky LWDR by integrating the traditional TIR bands and newly selected FIR bands. Through comprehensive simulations and analyses, we identify that the FIR bands can serve as an essential complement to existing TIR-based methods, thereby significantly improving the accuracy of LWDR estimation and yielding a 16% overall accuracy improvement. This substantial potential for enhanced accuracy is particularly evident under conditions of low water vapor content or in polar atmospheres, where improvements exceed 23%. This research represents the first incorporation of FIR into longwave radiation estimation fields, highlighting a promising advancement in remote sensing techniques. The findings inspire further exploration of FIR's potential and lay the groundwork for a deeper understanding of LWDR and the complexities of Earth's radiation balance, ultimately aiding in more accurate assessments of climate change.</div>
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