Primorye Upwelling System in the northwestern Japan Sea

Transcription

1 1 st WESTPAC Workshop on Upwelling and its Dynamics in the South China Sea and Adjacent Areas, May 7-8, 2018, Putrajaya, Malaysia Primorye Upwelling System in the northwestern Japan Sea Vyacheslav Lobanov V.I.Il ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia

2 Content 1. Introduction: geography of the Japan Sea 2. Seasonal wind induced upwelling along the northwestern coast 3. Mesoscale structure, role of the eddies 4. Slope and coastal mesoscale eddies 5. Changes of oceanographic structure and primary production 6. Ventilation of shelf area by upwelling intrusion 7. Conclusion

3 Main geographic features of the area Primorye coast Japan Sea -Deep semi-isolated basin (>3500 m), narrow shelf -Strong seasonal variation of SST, SSS and stratification -Along slope current, shear, shelf waves Владивосток

4 Primorye (Liman) Current south westward boundary current of the Japan Sea (Primorye Current, North Korean Current) Danchenkov et al., 2003

5 Seasonal wind induced upwelling

6 Main geographic features of the area Winter monsoon Primorye coast Transition period Japan Sea -Deep semi-isolated basin (>3500 m), narrow shelf -Strong seasonal variation of SST, SSS and stratification -Along slope current, shear, shelf waves -Monsoon winds, coastal upwelling Summer monsoon Владивосток

7 Upwelling along Primorye Coast (seasonal phenomenon, Sept-Oct) NOAA-IR (Ladychenko, 2016) L8-IR (Dubina, 2016)

8 Surface distribution of T, S, Sigma 0 and DO

9 Upwelling index: Seasonal favorable winds Monthly mean upwelling index (based on geostrophic wind) Positive values upwelling favorable Zhabin et al., 2017) Рисунок Карта, показывающая положение районов и узлов расчетной сетки (а) и среднемесячные значения индекса апвеллинга у побережья южного (б, в), восточного (г, д) и северо-восточного (е) Приморья. Крестиками отмечены точки, для которых был рассчитан накопленный индекс апвеллинга. Положительные значения индекса соответствуют ветровым условиям, благоприятным для развития апвеллинга

10 Mesoscale Structure of Primorye Upwelling System: Local upwellings and short-term variability caused by mesoscale eddies

11 Primorye Upwelling System : simultaneous wind induced upwelling along Primorye and short term fluctuations caused by mesoscale eddies Резкие колебания температуры воды в осенний период с амплитудой сравнимой с годовым ходом C температура Изменение МВАТ с 26 августа по 23 октября (суточное осреднение) дата Изменение у м. Крас с 22 августа по 25 октября (суточное осреднение) 16 Vladivostok Nakhodka теспература дата Изменнение БК с 22 августа по 30 октября (суточное осреднение) Оказывает влияние : - морской промысел (развитие морских ежей, ламинарии и др. в период нереста) - биоразнообразие прибрежной зоны - эффективная вентиляция прибрежной зоны температура дата POI and TINRO moorings in Aug-Oct 2003

12 Mesoscale Eddies along Primorye km

13 Mesoscale Eddies along Primorye Lobanov et al., 2001; Ladychenko et al. 2011; Ladychenko, Lobanov, 2013 z H - H = f H n r z º k Ñ v n H - Hn changes of depth across the slope; f Coriolis parameter; - vorticity component; Belonenko et al., 2016; off- and on- shelf motion changes vorticity and forms a wave along the slope

14 Modelled Primorye Slope Eddies Current velocity (top) and vorticity (bottom) in the upper mixed layer by quasi-isopycnal layered model in z-coordinate system (Shapiro and Mikhailova, 2001) 2,5 km, 10 layers Ponomarev et al., 2011 Lagrangian simulations, Prants et al. 2011

15 Vertical structure of Primorye Eddy

16 Reverse flow in the NW Japan Sea on satellite infrared images, October 7, 2011 Coastal upwelling area Reverse northeastward flow Mesoscale anticyclonic eddies

17 Reverse flow- surface drifters trajectories October 4 November 4, P P 174

18 Changes of oceanographic structure and primary production during upwelling

19 SST Structure Changes on Satellite Images Eddies Upwelling Gamov direction wind speed October October 2000

20 SST Changes in Fall Season Atmospheric cooling, convection - Wind induced upwelling o C 5.0 o C Formation of coastal eddies and upwelling event off Primorye on NOAA AVHRR infrared images Slow decrease of SST on the shelf and fast drop

21 Hydrographic sections: different changes at bottom layers in the eastern and western coastal stations S1 S2 S L1 S3: Upwelling and convective mixing off Preobrazhenie (134E) S1 S2 S3 L2 Formation of coastal eddies and upwelling event off Primorye on NOAA AVHRR infrared images Changes in T, S, density and nutrients along the sections S1 and S3 over 2-3 weeks period T, o C 10 m 50 m S S S1: Intrusion of deep sea water onto the shelf of Peter the Great Bay

22 Chl-a, pco2, Nutrients Before Т/NO NO 3 SiO 4 pco 2 Chl Станция 8 Z=70 SiO pco Chl Т/NO SiO 4 NO 3 pco 2 T SiO pco Chl T Станция 9 Z=106 Chl After Т/NO Станция 58 Z=88 T SiO 4 pco 2 Chl NO 3 SiO pco Chl Т/NO SiO 4 Chl NO 20 3 T pco 2 Станция 63 Z=26 SiO pco Chl Nutrients: Before: PP was limited by low nutrients, esp. Nitrates After: Gradual increase of nutrients caused by weakened stratification and uplift of picnocline pco2 profiles: - increased production in upper layer and destruction in lower layer after upwelling Vertical profiles of T, pco2, NO3, SiO4 and Chl a for some stations before (L1) and after (L2) upwelling

23 Chl-a and Primary Production Хлорофилл, мг/м (52-58) Vladivostok 2-7 (59-63) I Before Расстояние от берега, км Preobrazhenie Olga (37-43) Хлорофилл, мг/м (2-7) II 52-58(8-11) S (12-18) S Расстояние, км Chl a content in a photic layer along the sections in situ (more increasing in the west, more increasing at the coast) Daily Primary Production in a photic layer After S ПП (мгс/м2/день)_i ПП (мгс/м2/день)_ii_a Before After before Chl a SeaWiFS data (O.Kopelevich, S.Zakharkov, E.Streikhert) after

24 Changes in water mass structure and stratification S1 S3 T, o C S1 S3 10 m m MLD, m S1 S3 before after before after before after Intrusion area, wide shelf: -Initially: well mixed -Nutrients supply -Uplift of picnocline -Convective mixing - upper lr. -Decrease MLD Upwelling area, narrow shelf: - Initially: stratified - Nutrients supply - Vertical mixing - Weakening of stratification - Increase MLD On shore intrusion wide shelf S1 Eddy Upwelling, divergence narrow shelf S3

25 Ventilation of Peter the Great Bay by advection of deep sea water onto the shelf

26 Advection of deep sea water onto the shelf of PGB Water temperature in the Amursky Bay at 5 m and 26 m from July 12 to October 5, 2005 T surf T btm Проведенные в гг. измерения течений показали, что вторжения морских вод в придонном слое достигают полуостровава Песчаный и эффективно вентилируют воды Амурского залива в осенне-зимний период 18 Sept

27 Ecological problems of Primorye shelf area: Severe hypoxia of near-bottom layer in the Amurskiy Bay Lowest oxygen concentration was 4 µmol/kg. (1.5%) N surface bottom First finding! surface bottom E Distribution of oxygen concentration (umol/kg) in Amurskiy Bay, in surface and bottom layers. August, 2007 (upper panel). August, 2008 (bottom panel). 27

28 Ecological problems of Primorye shelf area: seasonal hypoxia of Amurskiy Bay Razdolnaya River Inputs Vladivostok City Inputs Stable ice New ice formation area Winter TS convection Deep Water Intrusion Drifting ice Amurskiy Bay is semiclosed basin. It is located in the northwestern part of Peter the Great Bay. Its length is about 70 km and depth varies from 0 up to 53 m (average depth is about 15 m). Square of the bay is about 1000 km 2. Annual river-runoff is 2.5 km 3. Population around Amurskiy Bay is 300,000. Northern part of the Bay is covered by ice in winter time. 28

29 Ecological problems of Primorye shelf area: seasonal hypoxia of Amurskiy Bay Razdolnaya River Inputs Winter TS convection Vladivostok City Inputs AOU, µmol/kg a Deep Water Intrusion O2, µmol/kg b months Amurskiy Bay is semiclosed basin. It is located in the northwestern part of Peter the Great Bay. Its length is about 70 km and depth varies from 0 up to 53 m (average depth is about 15 m). Square of the bay is about 1000 km 2. Annual river-runoff is 2.5 km 3. Population around Amurskiy Bay is 300,000. Northern part of the Bay is covered by ice in winter time. 29

30 Bosfor Vostohchniy Strait Mooring seasonal formation and abrupt destruction of hypoxia Amurskiy Bay Vladivostok T Ussuriyskiy Bay Ventilation of bottom layer DO H=48 m RDCP-600 Max of hypoxia

31 Ventilation of hypoxia in the Amurskiy Bay Abrupt changes of T, S и DO along the section crossing Amurskiy and Ussuriyskiy Bays 1-7 October Hypoxic zone T S DO

32 Ventilation of hypoxia in the Amurskiy Bay Abrupt changes of T, S и DO along the section crossing Amurskiy and Ussuriyskiy Bays 1-7 October and October, 2011 Hypoxic zone T S DO T S DO

33 Abrupt decrease of water temperature in Ussuriysky Bay, caused by advection stream, Sept T, o C o C in 6 hours, 16 o C in 1 day!

34 T, o C Inter-annual Variability of the Upwelling T, o C 18 а б Рис. в Изменение придонной температуры воды (Н=21.5 м) в южной части пролива Старка ( с.ш., в.д.): а г., б 2009 г., в 2010 г..

35 Conclusion 1. Seasonal upwelling develops at the northwestern Japan Sea along Primorye coast during transition of monsoon winds (September-October period). 2. Eddy dynamics leads to intensification of cross shelf transport, formation of local upwelling areas, changes of vertical stratification and increase of primary production 3. Water mass properties and primary productions most prominent because of advection of upwelled water onto the shelf 4. Ventilation of hypoxic conditions at peter the Great Bay slope by upwelling is very important 5. Upwelling brings high salinity water onto the shelf which controls winter convection processes and slope cascading in next winter