Laser-induced fluorescence lidar detection of weak biomass burning aerosols at Nanping, South China

Abstract. South China, a densely populated region frequently affected by transported biomass burning aerosols (BBA), is in need of sensitive remote sensing observations to characterize these plumes. Laser-induced fluorescence (LIF) lidar is powerful tool for detecting fluorescence aerosols and has recently been demonstrated to identify transported BBA over Europe, while its applications in South China remain scarce. Here, we present LIF lidar observations of fluorescent aerosols conducted at Nanping, South China. The detected fluorescence layer exhibited relatively weak intensity (maximum fluorescence backscatter coefficient ≈ 0.16×10⁻⁵ Mm⁻¹ Sr⁻¹ nm⁻¹), more than two orders of magnitude lower than the N₂ Raman backscatter signal. Nevertheless, it showed a distinct spectral signature compared with typical urban aerosols. By integrating multi-source datasets, the fluorescence layer was attributed to long-range transported BBA originating from weak fire activity in the Indo-China Peninsula (ICP). Furthermore, the concurrent presence of BBA and enhanced water vapor indicated a humid environment favorable for aerosol processing. This study demonstrates that multi-channel LIF lidar provides a sensitive and promising approach for detecting and characterizing BBA layers over South China, thereby offering new insights into their transport mechanisms and potential environmental impacts.