Fast-hyperspectral imaging remote sensing: Emission quantification of NO and SO from marine vessels.

Marine vessels play a vital role in the global economy; however, their negative impact on the marine atmospheric environment is a growing concern. Quantifying marine vessel emissions is an essential prerequisite for controlling these emissions and improving the marine atmospheric environment. Optical imaging remote sensing is a vital technique for quantifying marine vessel emissions. However, the available imaging techniques have suffered from insufficient detection accuracy and inadequate spatiotemporal resolution. Herein, we propose a fast-hyperspectral imaging remote sensing technique that achieved precise imaging of nitrogen dioxide (NO) and sulfur dioxide (SO) from marine vessels. Several key techniques are developed, including the coaxial design of three camera systems (hyperspectral camera, visible camera, and multiwavelength filters) and a high-precision temperature control system for a spectrometer (20 °C ± 0.5 °C). Moreover, based on the variation of O within them, plumes are categorized as aerosol-present and aerosol-absent, with different air mass factor (AMF) calculation schemes developed accordingly. Multiwavelength filters combined with spectral analysis enable precise identification of the plume outline and a detailed observation of the trace gas distribution inside the plume emitted from marine vessels. In addition, we focuse on the emission characteristics of NO and SO from large ocean cargo ships and small offshore cargo ships. Although there are still many emerging issues, such as measurement of cross-sections of trace gases at different temperature, nighttime imaging, and greenhouse gas imaging, this study opens a gate for synergies in pollution and carbon reductions and the continuous improvement of the marine atmospheric environment.