[ACG38-P17] Optical tracer method to distinguish fresh water sources in the Pacific Arctic region
Keywords:absorption of CDOM, Pacific Arctic region, fresh water sources
We obtained salinity, TA, and aCDOM at 443 nm (aCDOM(443)) from the seven cruises of R/V Mirai conducted in the Pacific Arctic region during late summer. Fraction of sea ice melt water (fSIM) and other fresh water (fOF) were calculated from their known end-member values of salinity and TA. We identified aCDOM(443) end-member values of fSIM and fOF, which were unknown, applying a least-square method to the relationship between fresh water fraction and aCDOM(443). Thus, fSIM and fOF became retrievable from salinity and aCDOM(443) instead of TA. We also evaluated the accuracy of the optical tracer method comparing fresh water fraction values calculated from chemical and optical tracers, and obtained equivalent results to the chemical tracer method. Estimation of fresh water sources with higher frequent monitoring using aCDOM might advance the comprehension of ocean circulation and related chemical- and biological system in the Arctic.