Interannual variation of the upper portion of the Japan Sea Proper Water and its probable cause

Abstract

The long-term variation of water properties in the upper portion of the Japan Sea Proper Water (UJSPW) is examined on the basis of hydrographic data at PM10, located on the northwestern Japan Sea, and at PM05, in the Yamato Basin, taken from 1965 through 1982. At PM10, located at the southern boundary of the UJSPW formation region, dissolved oxygen fluctuations on the UJSPW core showed negative correlation with phosphate variations, but showed no significant correlation with salinity variations. At PM05 water properties fluctuated with smaller amplitudes than those at PM10 except for salinity. Dissolved oxygen variations at PM10 lead those at PM05 by 12-15 months, suggesting that the UJSPW near PM10 circulates into the Yamato Basin spending 12-15 months. Increases of dissolved oxygen contents in summer on relevant isopycnal surfaces at PM10 occurred after cold and/or windy winters except for two of eight; this suggests that larger volume of the UJSPW is formed in severe winter. Rough estimations of the formation rate and existing volume of the UJSPW are made on the basis of a climatological dataset; 1.5 × 10 4 km 3 yr -1 and 27.3 × 10 4 km 3 , respectively. The ventilation time of the UJSPW, 18.2 years, is about one tenth or less of residence time for the entire Japan Sea Proper Water. This indicates that the UJSPW is renewed about ten times as quick as the deeper water.

Possible source of advected water mass and residence times in the multi‐structured Sea of Japan using rare earth elements

“…Then, τ is estimated to be ≈15 years for Water Mass III and ≈38 years for Water Mass II (Figure 4). The results compare favorably with earlier estimates for some of the water masses: 18.2 years for Water Mass III on the σ 1 of 32.03 kg m −3 , corresponding to an average water depth of 375 m, by Senjyu and Sudo [1996]; 2.1 years in a water mass shallower than 200 m by Yanagi [2002], and 120 years in water deeper than 2000 m reported by Chen et al [1995]. Together with these previous estimates, the volume‐weighted average residence time of JSPW in the central Japan Basin is calculated to be >86 years (Figure 4), assuming τ > 120 years for the oldest water mass (characterized by low DO) in the depth range of 1500–2000 m. This estimate of τ > 86 years in JSPW is improved over previous estimates by taking into account more explicitly the multiple vertical strata in the Japan Basin; this result is in agreement with those of Watanabe et al [1991] (100 years) and Yanagi [2002] (90 years).…”

Simulation of eddy-driven deep circulation in the East/Japan Sea by using a three-layer model with wind, throughflow and deep water formation forcings

“…3). DWF in the middle layer as applied in this study is supported by observations in the East/Japan Sea (Gamo et al, 2001;Kim et al, 2004;Senjyu and Sudo, 1996;Seung and Yoon, 1995). Deep water formation is replaced with eddy formation in this study.…”

“…The volume and maximum formation area of newly formed deep water are about 0.1 Sv and 3.14 × 10 4 km 2 in this model, respectively. Maximum formation area in the model is similar to the observation (3.0 × 10 4 km 2 ), and the volume of newly formed deep water amounts to about 20% of the volume (0.48 Sv) estimated from hydrographic observation in the East/Japan Sea (Senjyu and Sudo, 1996). Six experiments were carried out, as summarized in Table 1.…”

Changes in seawater N : P ratios in the northwestern Pacific Ocean in response to increasing atmospheric N deposition: Results from the East (Japan) Sea

“…Since this sea is fully closed below the 100 m layer, the horizontal water advection can be neglected in this mass balance. The N and P fluxes from the deep to surface layers through physical mixing are calculated to be 3.5 3 10 11 mol N yr 21 and 0.26 3 10 11 mol P yr 21 by multiplying the vertical water exchange rate of 15 3 10 12 m 3 yr 21 through 200 m (Senjyu and Sudo 1996) by the average nutrient concentrations in the deep sea observed from 2001 to 2009 (23 6 2 mmol L 21 for N and 1.8 6 0.2 mmol L 21 for P). Since the vertical input terms (F organic export ) will be balanced by the vertical output terms (F mixing ), under steady state conditions (I (y) 5 I (y21) ), in the deep layer, the N and P fluxes from the surface to deep layers through physical mixing are calculated to be 1.2 3 10 11 mol N yr 21 and 0.12 3 10 11 mol P yr 21 , respectively.…”