## 3 Results and Discussions  
Molecular Distributions and Temporal Variation in Dicarboxylic Acids, Oxacids, Benzoic Acid, and Fatty Acids  
We summarize the concentrations of organics: organic carbon and diacids, oxoacids, benzoic acid, and fatty acids obtained (Table S1). Carboxylic acids and OC were obtained by the GC and carbon analyzer, respectively. A homologous series of \(\alpha\),\(\omega\)-dicarboxylic acids (C\({}_{2}\)-C\({}_{12}\)), unsaturated diacids (phthalic, isophthal, terephthalalic, maleic, fumaric and methylmaleic), multifunctional diacids (malic, ketomalonic, and 4-ketopimelic), oxoac-boxylic acids (\(\omega\)C\({}_{2}\)-\(\omega\)C\({}_{9}\) and pyruvic acid), and \(\alpha\)-dicarbonyls (glyoxal and methylglyoxal), benzoic acid and fatty acids was detected in the PM\({}_{1,0}\) samples collected during the campaign. Oxalic acid (C\({}_{2}\)) was found as the most abundant organic species followed by malonic (C\({}_{3}\)), succinic (C\({}_{4}\)), glyoxylic (\(\omega\)C\({}_{2}\)), ketomalonic (kC\({}_{3}\)), and phthalic (Ph) acids. The predominances of C\({}_{2}\) in diacids and \(\omega\)C\({}_{2}\) in oxoacids indicate a significant photochemical oxidation of organic precursors in both gaseous and aqueous phases during long-range atmospheric transport [13, 49, 72, 73, 74, 75, 76, 77]. Their predominance is due to secondary formation from both biogenic and anthropogenic sources. 9-Oxononanoic (\(\omega\)C\({}_{9}\)) is produced by the photo-oxidation of biogenic unsaturated fatty acids such as oleic acid [78]. Benzoic acid is emitted from automobile exhausts [79]. [PERSON] et al. [75] reported that a secondary formation is the dominant source of organic acids in Okinawa from their precursors. Total diacids are defined as the sum of all the diacids detected. The relative abundance of C\({}_{2}\) is defined as the C\({}_{2}\) (%) of total diacid concentration; C\({}_{2}\) (%) = (concentration of C\({}_{2}\)/concentration of total diacids) \(\times\) 100. During the campaign, the average C\({}_{2}\) (%) was 75%. The sum of major diacids (C\({}_{2}\), C\({}_{3}\), C\({}_{4}\) and kC\({}_{7}\)) comprised 96.4% of \(\Sigma\)C\({}_{2}\)-C\({}_{12}\) diacids (summation of C\({}_{2}\) to C\({}_{12}\)) (not shown as a figure). Similarly, the relative abundance of \(\omega\)C\({}_{2}\) in total oxoacids was 81%. The sum of \(\omega\)C\({}_{2}\) and \(\omega\)C\({}_{9}\) comprised 90% of total oxoacids. C\({}_{2}\), C\({}_{3}\), C\({}_{4}\), kC\({}_{7}\), \(\omega\)C\({}_{2}\), \(\omega\)C\({}_{9}\), and benzoic acid are major carboxylic acids that constitute the molecular compositions of diacids and related compounds. We calculated the acid mass concentration according to [PERSON] et al. [41]. The acid mass fraction for selected diacids and related compounds (concentrations of diacids, oxoacids, benzoic acid, pyruvic acid, and fatty acids/OrgAMS) was 0.08, whereas the ratio of m/z 44/OrgAMS was 0.12. The fraction of carboxylic acids obtained from GC measurement was 1.5 times lower than that from AMS m/z 44, suggesting the presence of other organic acids including monoacids such as formic, acetic, and propanoic acids. Interestingly, high abundances of formic and acetic acids were reported in gas and particle phases from Mt. Tai in the North China Plain [80]. We selected total diacids, total oxoacids, benzoic acid, and total fatty acids to compare with AMS m/z 44 signals (Table S1). Figure 2 shows the average relative abundances of total diacids, total oxoacids, benzoic acid, and total fatty acids in total carboxylic acids. The average relative abundance of total diacids in total carboxylic acids is 70.7%, followed by total fatty acids (18%), total oxoacids (7%), and benzoic acid (4.4%). The higher % of diacids suggests that dominant organics are formed from secondary formation. We consider that the above-mentioned carboxylic acids can potentially contribute to the m/z 44 signals obtained by AMS [40].