## 1 Introduction  
Organic aerosols (OA) are a ubiquitous and abundant component in the atmosphere. They account for 20-50% of the fine particle mass [1, 2, 3, 4] and can be primarily formed by fossil fuel combustion and biomass burning [5] and secondarily by gas-to-particle conversion of volatile organic compounds (VOCs) via photochemical processing with O\({}_{3}\) and OH radicals [6, 7, 8, 9, 10]. In both continental and marine aerosols, oxalic acid has been reported as the most abundant dicarboxylic acid followed by malonic and/or succinic acid using gas chromatography (GC) and the GC/mass spectrometer [11, 12, 13].  
Low-molecular-weight (LMW) dicarboxylic acids (hereafter, diacids) and other organic acids are ubiquitous in the atmosphere, with high concentrations up to few \(\upmu\)g m\({}^{-3}\)[14, 15, 16, 17, 18, 19], demonstrating that they are the most important constituents of tropospheric OA [13, 20]. Diacids and related compounds can contribute to 0.2-1.8% of total carbon (TC) in urban aerosols from Tokyo [14] and up to 16% of TC in remote marine aerosols from the central Pacific, including the tropics [11]. Previous studies demonstrated that diacids account for up to 10-27% of organic carbon (OC) in aerosols, e.g., [13; 21; 22].  
Although air pollutants in East Asia have largely increased in recent decades with a significant influence over the continents and ocean on regional and global scales [23], levels of some pollutants such as sulfate started to decline recently in Chinese megacities and outflow regions [24; 25], except for surface ozone [26] and water-soluble dicarboxylic acids [27]. Organic aerosols emitted from East Asia are transported to the western North Pacific Rim, including Okinawa Island [28]. [PERSON] et al. [29] utilized an aerosol mass spectrometer (AMS) at Cape Hedo, Okinawa, to study the ambient aerosols influenced from East Asia and reported a good relation between AMS m/z 44 and water-soluble organic carbon (WSOC). The AMS studies for organic aerosols have been reported from many field campaigns [30; 31; 32; 33; 34; 35; 36; 37]. The AMS signal of m/z 44, mainly originating from CO\({}_{2}\)\({}^{+}\), have been used as a marker for oxygenated organics in urban areas [38; 39; 40; 41].  
However, direct comparison is lacking between AMS-derived m/z 44 (COO\({}^{+}\)) signals and GC-measured carboxylic acids in aerosols, except one comparison reported in urban Tokyo [40]. Although there are many studies about m/z 44 (COO\({}^{+}\)) by AMS [41; 42; 43; 44; 45; 46; 47], a direct comparison of various types of carboxylic acids determined by GC/FID with on-line AMS measurement has not been conducted from remote oceanic sites.  
In this study, we measured various types of carboxylic acids, including diacids, oxoacids, and fatty acids, in coastal aerosols collected from Cape Hedo, Okinawa Island, using butyl ester derivatization for off-line GC determination. AMS measurements were also conducted on-line at the same site during the same campaign. The concentrations of those acids were compared with those of m/z 44 (COO\({}^{+}\)) signals obtained by on-line AMS at the same site. Here, we compare, for the first time, the GC/FID results of various dicarboxylic acids and related compounds with AMS-derived m/z 44 signals for the marine aerosol particles from the western North Pacific Rim.