Chemical composition measured during cruise MR18-06 Leg4 of RV Mirai in March 2019. This dataset contains the abundance of chloride, nitrate, sulfate, sodium, ammonium, potassium, magnesium, calcium, organic carbon, and elemental carbon. The inoganic ion mass concentration of aerosol particles were analyzed by ion chromatography (ICS-1000,Dionex). Thermal/optical carbon analyzer (DRI model 2001, Desert Research Institute) has been used for determining the organic and elemental carbon concentration.