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A bio-optical dataset collected during the 1998-2007 period in the Yellow and East China Seas (YECS) was used to provide alternative empirical ocean-color algorithms in the retrieval of chlorophyll- a (Chl- a), total suspended matter (TSM), and colored dissolved organic matter (CDOM) absorption coefficients at 440 nm (ag). Assuming that remote-sensing reflectance (Rrs) could be retrieved accurately, empirical algorithms for T (regionally tuned Tassan's Chl- a algorithm) in case-1 waters (T2i in case-2 waters), T (regionally tuned Tassan's TSM algorithm), and T or C (regionally tuned Tassan's or Carder's ag algorithm) were able to retrieve Chl- a, TSM, and ag with uncertainties as high as 35, 46, and 35%, respectively. Applying the standard SeaWiFS Rrs, T was not viable in the eastern part of the YECS, which was associated with an inaccurate SeaWiFS Rrs retrieval because of improper atmospheric correction. T behaved better than other algorithms in the turbid case-2 waters, although overestimation was still observed. To retrieve more reliable Chl- a estimates with standard SeaWiFS Rrs in turbid water (a proxy for case-2 waters), we modified T for data with SeaWiFS normalized water-leaving radiance at 555 nm (nLw) > 2 mW cm μm sr (T2s). Finally, with standard SeaWiFS Rrs, we recommend switching algorithms from T2s (for case-2 waters) to MOC (SeaWiFS-modified NASA OC4v4 standard algorithm for case-1 waters) for retrieving Chl- a, which resulted in uncertainties as high as 49%. To retrieve TSM and ag using SeaWiFS Rrs, we recommend empirical algorithms for T (pre-SeaWiFS-modified form) and MT or MC (SeaWiFS Rrs-modified forms of T or C). These could retrieve with uncertainties as high as 82 and 52%, respectively. [ABSTRACT FROM AUTHOR]

To forecast haze pollution episodes caused by high concentrations of long-range transported pollutants emitted in the areas upstream of South Korea, it is crucial to study and identify their behaviour. We analysed the three-dimensional air quality structure in Seoul using ground observation data and aerosol lidar measurements to identify vertical aerosol intrusion into the Korean Peninsula during the spring of 2016. The intrusions were particularly affected by the development of the atmospheric boundary layer (ABL) in the leeward regions. The nocturnal pollutant intrusion into the Korean peninsula via the Yellow Sea was examined using measured data. The pollutants first reached the area above the nocturnal boundary layer (548 ± 180 m) and approached ground level on the following day due to convective mixing depending on the convective ABL growth (1182 ± 540 m) in daytime. These intrusion mechanisms were mostly attributed to extremely high concentrations (i.e. >100 μg m−3) of fine particulate matter in the leeward regions, accounting for four of the total of six cases for which the warnings and alerts were issued in Seoul Metropolitan Area over a year-long period (2016). The horizontal and vertical pathways of the long-range transported pollutants and the atmospheric vertical structure were identified as key factors affecting the surface air quality concentration in the leeward regions. [ABSTRACT FROM AUTHOR]