Japan Sea Intermediate Water (JSIW) is in the salinity-minimum layer present between the thermocline and deep water in the Japan Sea. Annual shipboard measurements over the past 20 years revealed that JSIW rapidly freshened in the 2010s, particularly from 2010 to 2011, from 2012 to 2013, and from 2015 to 2016. The mean rate of salinity change at σθ = 27.16 kg m−3 (σθ indicates potential density minus 1000 kg m-3) in JSIW was − 0.078 ± 0.013 per decade (mean ± standard error) from 2009 to 2016. This rate is more than twice of those observed in intermediate waters in open oceans. The Polar Front in the Japan Sea, the boundary between the subtropical and subpolar waters, considered the JSIW formation region. Using a biogeochemical tracer PO = [O2] + [PO4] × 135, it was determined that the contribution of less saline water from the south of the Polar Front increased in JSIW in the 2010s. The atmospheric and oceanic reanalysis data indicated that a large freshwater influx from the East China Sea to the Tsushima Strait in the summers contributed to the freshening in the south of the Polar Front in 2010 and 2012, whereas, a large local precipitation in the autumn freshened in the region in 2015.

中文翻译：

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2010 年代日本海中水的快速清新

日本海中层水 (JSIW) 位于日本海温跃层和深水之间的最低盐度层。过去 20 年的年度船上测量显示，JSIW 在 2010 年代迅速更新，特别是从 2010 年到 2011 年、2012 年到 2013 年和 2015 年到 2016 年。 σθ = 27.16 kg m−3 (σθ表示从 2009 年到 2016 年，JSIW 中的潜在密度减去 1000 kg m-3) 为 − 0.078 ± 0.013 每十年（平均值 ± 标准误差）。这个比率是在公海中间水域观察到的比率的两倍多。日本海的极地锋是亚热带和次极地水域之间的边界，被认为是 JSIW 形成区。使用生物地球化学示踪剂 PO = [O2] + [PO4] × 135，确定在 2010 年代，极地锋以南较少咸水的贡献在 JSIW 中有所增加。大气和海洋再分析数据表明，2010 年和 2012 年夏季东海大量淡水涌入对马海峡导致了极地锋以南地区的清新，而秋季大量的局地降水使极地锋以南地区变得清新。 2015 年在该地区。