Jun-Heon Jang, Kyung-Il Chang, Seung-Tae Yoon, Hanna Na. SEES/Seoul National University

Transcription

1 Jun-Heon Jang, Kyung-Il Chang, Seung-Tae Yoon, Hanna Na SEES/Seoul National University

2 North Pacific Ecosystem Status Report Japan/East Sea

3 Temperature & DO changes in the Japan Basin аномалия модальной температуры, о C аномалия модальной температуры, о C 1. февраль-апрель июнь-август Temperature anomalies for the layer from seasonal thermocline to 2 m at the standard section 41 о 3 43 o N 132 о E averaged for February-April and June-September. (Yury Zuenko) Long-term trends of potential temperature and dissolved oxygen contents of bottom water in the Japan Basin (Vyacheslav Lobanov)

4 Temperature & DO changes in the Yamato Basin m m m m DO (ml l -1 ) Time series of the vertical profiles in potential temperature and dissolved oxygen below the depth of 5 m measured in the Yamato Basin (Tomoharu Senjyu). 12m m m m

5 Upper Ocean Heat Contents (Na et al., 211)

6 2 nd CSEOF Mode Decadal mode with linear trend (Na et al., 211)

7 Hydrography & Circulation of the Ulleung Basin Mitchell et al. (25)

8 Hydrography & Circulation of the Ulleung Basin Chang et al. (22) EKWC: 1.4 Sv NKCC:.8 Sv

9 EKWC & UWE Neither EKWC nor UWE

10 Regular bimonthly hydrographic stations since 1961 National Fisheries Research & Development Institute

11 Temperature trends m m o E 129 o E 13 o E 131 o E 132 o E o E 129 o E 13 o E 131 o E 132 o E m m o E 129 o E 13 o E 131 o E 132 o E o E 129 o E 13 o E 131 o E 132 o E -.4

12 Temperature trends along sections

13 Temperature trends along sections T trend( /year)(17line) =.6112 = T trend( /year)(16line) =.6944 = T trend( /year)(15line) =.6471 = depth(m) station depth(m) station depth(m) station Distance(km) Distance(km) Distance(km) -.2 T trend( /year)(14line) = = T trend( /year)(13line) =.5852 = T trend( /year)(12line) = = Depth(m) Station Distance(km) depth(m) station Distance(km) depth(m) station Distance(km)

14 Temperature trends in Korea Strait T trend( /year)(28line) =.4495 = T trend( /year)(29line) = = depth(m) station depth(m) station Distance(km) Distance(km) -.4

15 Mean temperature & trends (line 14) T trend( /year) & Mean T(14line) = = Depth(m) Station Distance(km) -.2

16 Seasonal temperature trends Trend Feb Trend Apr Trend June o E 129 o E 13 o E 131 o E 132 o E o E 129 o E 13 o E 131 o E 132 o E o E 129 o E 13 o E 131 o E 132 o E Trend Aug Trend Oct Trend Dec o E 129 o E 13 o E 131 o E 132 o E 128 o E 129 o E 13 o E 131 o E 132 o E o E 129 o E 13 o E 131 o E 132 o E -.25

17 Basin-averaged annual mean temperature 18 Annual Mean m Mean(1987~21)= Annual Mean 2m Mean(1987~21)= Temperature( ) Temperature( ) Time(year) Time(year)

18 Decadal temperature trends m m o E 129 o E 13 o E 131 o E 132 o E o E 129 o E 13 o E 131 o E 132 o E m m o E 129 o E 13 o E 131 o E 132 o E o E 129 o E 13 o E 131 o E 132 o E -.2

19 Possible causes of subsurface cooling Changes in eddy statistics and structure Upper circulation variability Air-sea interaction (local & remote) Colder water advection (ESIW, NKCC)

20 Mean net surface heat flux (MERRA) Ulleung Basin Annual East Sea Summer Winter

21 Mean net surface heat flux (MERRA)

22 Time series at T( )at 75m mean=11.27 Range(2.7~ ) T trend( /year)(14line) = = Station Temperature( ) Depth(m) /year time T( )at 2m mean= Range(.82~ 1.8 ) Distance(km) Temperature( ) /year T mean = 2.5 C.8 C < T < 1.8 C time

23 T( )at 2m mean= Range(.82~ 1.8 ) -.621/year Temperature sections along 14-line Temperature( ) time 14line 93 2 Temperature( ) =11.92 = Station line 93 6 Temperature( ) =19.8 =.68 Station Depth(m) Depth(m) Distance(km) Distance(km) 2 4 2

24 Temperature trends excluding T > T mean ±σ m T > T mean ±σ m T > T mean ±σ o E 129 o E 13 o E 131 o E 132 o E o E 129 o E 13 o E 131 o E 132 o E m m o E 129 o E 13 o E 131 o E 132 o E o E 129 o E 13 o E 131 o E 132 o E -.2

25 Current Measurements line 14

26 Current Measurements

27 Mean currents and std ellipses Mean Currents Common period

28 Time series of low-passed currents

29 Time series of U, V, T at UB2

30 Correlation and Regression between V198 & T2

31 Observed & Estimated V

32 Observed & Estimated V Linear trends - T : -.64 /year - V : cm/s/year (8 km*5 m*.1*.1 =.4 Sv/yr)

33 Summary Data: NFRDI, 1987~21 (CTD data) Decreasing trend of subsurface temperature in the Ulleung Basin below 1 m. The cooling is pronounced in water layers occupied by the ESIW and the NKCC water. The decreasing rate is higher in summer as compared to that in other seasons. Decadal variation at 2 m, a sharp decrease before 1996 and gradual increase afterwards. Eddy variability seems little influence the decreasing trend. Temperature and north-south velocity are well correlated at the base of the continental slope. Decreasing trend of temperature accompanies with an intensification of southward flows.