Survey of current hyperspectral Earth observation applications from space and synergies with Sentinel-2

Abstract

In the last decades, researchers developed a plethora of hyperspectral Earth observation remote sensing techniques, analysis and applications. While hyperspectral exploratory sensors are demonstrating their potential, satellite remote sensing has simultaneously entered a new era. Multispectral sensors with short revisiting period are now acquiring free, open, global and systematic high resolution visible and infrared imagery. More specifically, Sentinel-2 sensors broke down the barrier between hyper- and multispectral imaging. This sensor optimizes its number of potential applications thanks to numerous narrow bands spanning on a significant range of the spectrum at a high spatial resolution. The recent release of this high performance multispectral instrument calls thus the relevance of hyperspectral spaceborne imaging of medium spatial resolution into question and suggests potential synergies between those two kinds of data. In order to clarify this concern, we tried to identify through a comprehensive review the current and future applications for hyperspectral sensors in the Sentinel-2 context. This study therefore reviews 20 years of researches and applications in satellite hyperspectral remote sensing through the analysis of Earth observation (EO) hyperspectral sensors' publications that cover the Sentinel-2 spectrum range: Hyperion, TianGong-1, PRISMA, HYSI, EnMAP, HISUI, Shalom and HyspIRI. More specifically, this study (i) identifies the most useful wavelengths that are not available on Sentinel-2 and (ii) assesses the assets and the limitations of hyperspectral spaceborne sensors for operational EO. Applications using Sentinel-2 are still uncovered, including some demonstrations made with hyperspectral systems. However, the medium spatial resolution and the long revisit time of hyperspectral sensors, and the low signal-to-noise ratio in the short-wave infrared of Hyperion were highlighted as major limitations for hyperspectral applications compared to the Sentinel-2 system. Forthcoming hyperspectral sensors will probably overcome these constraints. This study is putting forward the compatibility of hyperspectral and Sentinel-2 systems for resolution enhancement techniques, and thus for increasing even more the panel of hyperspectral uses, but also the promising future of hyperspectral remote sensing.