Impacts of freshwater originating from the Changjiang discharge flowing from the East China Sea on the thermohaline circulation in the Japan Sea

1.对马海峡的盐度变化（1）根据历史观测资料，研究了对马海峡盐度的年际变化。分析表明，东、西通道的同相变化是最主要的模态。该模态与长江流量的变化有关，长江流量大时，海峡盐度在夏季有降低的趋势。建立了由降水异常估算长江流量的多元回归模型。(2)An 2004-2005年，利用停泊在对马海峡二井岛的TS测量仪进行了表层温度和盐度的观测。盐度具有明显的季节变化，每年7月中旬盐度迅速下降，8月中旬盐度最低。但2005年盐度下降速度比2004年快20天左右，最低值比2004年低1-2 psu。TS计记录表明，6 ~ 7月，海峡内有高温低盐水团的周期性通过。2.日本海的温盐环流（1）根据直接海流测量资料，对日本海的深海环流进行了研究。平均气流矢量的分布表明，沿沿着海盆外围有较强的气旋性环流。与此相反，缓慢的平均流被发现在内部区域，因为涡动占主导地位。（2）大和盆地底层水（YBBW）比日本盆地底层水（JBBW）具有更高的温度和更低的溶解氧。两个底层沃茨在大和盆地和日本盆地之间的边界附近汇合，形成一个清晰的底栖前缘。YBBW是流入大和盆地的改良JBBW。箱形模型估算出黄海黄脊湾的周转时间和垂直扩散系数分别为9.1年和3.4×10^<-3>m^<-3>s^<-1>。

1.Salinity variation in the Tsushima Strait(1)Interannual salinity variations in the Tsushima Strait were investigated based on the historical observation data. The EOF analysis revealed that the most dominant mode is the in-phase variation between the eastern and western channels. This mode correlates with the Changjiang discharge variation, and salinity in the strait tends to decrease over summer related to a large discharge of the Changjiang. The multi-regression model to estimate the Changjiang discharge from precipitation anomalies was developed.(2)An observation of surface temperature and salinity was carried out by a TS-meter moored at Futaoi Island in the Tsushima Strait in 2004-2005. Salinity shows a clear seasonal variation with a rapid decrease in mid-July and a minimum in mid-August in each year. However, salinity in 2005 decreased faster than that in 2004 by about 20 days and the minimum in 2005 was lower than that in 2004 by 1-2 psu. The TS-meter records suggest a periodic passage of water masses with a higher temperature and lower salinity in the strait in June-July.2.Thermohaline circulation in the Japan Sea(1)The abyssal circulation in the Japan Sea was investigated based on the direct current measurements. The distribution of mean flow vectors indicates relatively strong cyclonic circulations along the basin periphery. In contrast, sluggish mean flows are found in the interior region because of eddy motions dominancy.(2)The Yamato Basin Bottom Water (YBBW) exhibits higher temperature and lower dissolved oxygen than those in the Japan Basin Bottom Water (JBBW). Both bottom waters meet around the boundary between the Yamato and Japan Basins, forming a clear benthic front. The YBBW is the modified JBBW flowing into the Yamato Basin. A box-model estimated the turnover time and vertical diffusivity for the YBBW as 9.1 years and 3.4×10^<-3> m^<-3>s^<-1>, respectively.