Fast-hyperspectral imaging remote sensing: Emission quantification of NO₂ and SO₂ 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 (NO₂) and sulfur dioxide (SO₂) 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 O₄ 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 NO₂ and SO₂ 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.