Marine aerosol samples were collected during a western Pacific cruise covering the latitude range between 35¿N and 40¿S (140¿E--180¿E). They were analyzed for total carbon (TC), total nitrogen (TN), water-soluble organic carbon (WSOC) along with the molecular distributions of C2--C10 α, ω-dicarboxylic acids, and related polar compounds, mainly, ω-oxocarboxylic acids (C2--C9) and α-dicarbonyls (C2--C3). Oxalic acid (C2) was the most abundant followed by malonic (C3) and succinic (C4) acids. The total diacid concentration range was 7--605 ng m-3 (av. 85 ng m-3) and the diacid-carbon accounted for 2--15% (average 8%) of WSOC which comprised 29--55% (average 40%) of TC. Dry depositions of total diacids over the northern and southern Pacific Ocean were estimated to be 256--1907 ¿g m-2 yr-1 (average 735; n = 4) and 22--396 ¿g m-2 yr-1 (average 134; n = 14), respectively, whereas the air-to-sea flux of oxalic acid was 18--1351 ¿g m-2 yr-1 (average 466 ¿g m-2 yr-1) and 7.5--275 ¿g m-2 yr-1 (average 75 ¿g m-2 yr-1) in the Northern and Southern Hemispheres. We observed that the concentration ratios of diacid-C/WSOC, azelaic acid (C9)/ω-oxononanoic acid, maleic acid (iC4 cis)/fumaric (iC4 trans) acid and succinic acid (C4)/total diacids were correlated with air temperature. These findings showed that the intensity of photochemical oxidation reactions and thus the variation in sunlight intensity characterized here by air temperature, significantly control the molecular distribution of water-soluble organic compounds during the long-range transport of anthropogenic and/or biogenic higher molecular weight organic compounds.