鲁汶流是东印度洋海区低盐暖水向极传输的主要途径,不仅显著调节低纬-高纬海区间的温盐分配,也极大影响澳大利亚西岸降水,理解其在地质历史时期的变化及影响因素,对于认识区域和全球气候变化具有重要意义。本次研究将鲁汶流区采集的SO18...鲁汶流是东印度洋海区低盐暖水向极传输的主要途径,不仅显著调节低纬-高纬海区间的温盐分配,也极大影响澳大利亚西岸降水,理解其在地质历史时期的变化及影响因素,对于认识区域和全球气候变化具有重要意义。本次研究将鲁汶流区采集的SO18588孔岩芯上部63 cm沉积物作为研究材料,并以1 cm为间隔对其进行采样,共计获得63个沉积物样品。通过对这些沉积物样品进行研究,发现在SO18588站处浮游有孔虫热带表层水种Trilobatus sacculifer的相对丰度比浮游有孔虫热带-亚热带表层水种Globigerinoides ruber的相对丰度更适合被用于指示鲁汶流强度变化;之后,利用浮游有孔虫热带表层水种T.sacculifer的相对丰度,重建了32 ka B. P.以来鲁汶流的强度变化,并与已发表的古海洋和古气候学记录进行了对比。结果显示,鲁汶流强度的冰期-间冰期变化受海平面升降和类厄尔尼诺-南方涛动气候态共同调控:冰期时海平面下降,类厄尔尼诺态强化,导致鲁汶流减弱;间冰期时,海平面上升,类拉尼娜态发育,造成鲁汶流增强。9.5~0 ka B. P.期间,鲁汶流强度的持续弱化,可能归因于澳洲冬季风的减弱和早全新世类拉尼娜格局向现代类厄尔尼诺格局转变所造成的厄尔尼诺事件频发;9.5 ka B. P.左右鲁汶流强度事件性地突然减弱,可能与海平面上升所导致的卡里马塔海峡贯通、印尼穿越流表层流被抑制有关。展开更多
During the 134 （1996 1997） and the 19th （2002-2003） Chinese National Antarctica Research Expeditions, we collected 60 discrete surface seawater samples along the cruise from the Chanjiang River （Yangtze） estuary...During the 134 （1996 1997） and the 19th （2002-2003） Chinese National Antarctica Research Expeditions, we collected 60 discrete surface seawater samples along the cruise from the Chanjiang River （Yangtze） estuary （30^.59%, 122^.26＇E） through Taiwan Strait, the South China Sea, and the Eastern Indian Ocean to Prydz Bay, Antarctica （69^.10＇S, 74^.30＇E）, and analyzed them for the 226Ra specific activity. The 226Ra specific activity of the Chanjiang River estuary surface water （3.15 Bq/m3） was found to be the highest among all the surface samples because of the desorption of 226Ra from riverine particles. Between Chanjiang River estuary and 40^.S, 226Ra specific activity was found to be relatively uniform with a mean value of 1.07 Bq/m3 （n= 19, SD=0.14）, similar to that of the open ocean. From 40^.S to 65^.S, 226Ra specific activity increased intensively, then decreased moderately further southwards. Near the Antarctic shore, it increased again, to 2.31 Bq/m3. This distribution was controlled by a combination of deep water upwelling, Southern Ocean fronts, water mixing and the continental 226Ra import. In Prydz Bay and the adjacent sea area, the mean 226Ra activity value was 2.26 Bq/m3 （n=31, SD=0.28）, with a relatively higher value outside of the bay and low 226Ra activity value in the center of the bay. This was consistent with the topography and hydrological setting of the bay. In addition, we extended the study area northward to the Arctic, by combining the published Z26Ra dataset for surface water from the Bering Sea to the Japan Sea. We also discuss the 226Ra distribution of high latitude oceanic surface water and its mechanisms.展开更多
Along the downwelling coast off Western Australia, late-austral-autumn/early-austral-winter chlorophyll a blooms are observed on the continental shelf south of the Shark Bay (26° S). The late-austral-autumn/early...Along the downwelling coast off Western Australia, late-austral-autumn/early-austral-winter chlorophyll a blooms are observed on the continental shelf south of the Shark Bay (26° S). The late-austral-autumn/early-austral-winter blooms are in phase with seasonal strengthening of the Leeuwin Current and its eddy field. From satellite altimeter and ocean color data , anticyclonic eddies are found to entrain the high phytoplankton biomass waters from the shelf and transport them offshore into the oligotrophic, subtropical marine environment. The late-austral-autumn/early-austral-winter blooms are highly linked with enhanced horizontal mixing by mesoscale eddies in the region, as derived from the finite-size Lyapunov exponent (FSLE) of the surface geostrophic flow field obtained from satellite altimeter data. The pathways of cross-shelf exchanges, which are mostly driven by the mesoscale eddies, are revealed with coalescing of the FSLE of the surface geostrophic flow field and the satellite chlorophyll a images.展开更多
文摘鲁汶流是东印度洋海区低盐暖水向极传输的主要途径,不仅显著调节低纬-高纬海区间的温盐分配,也极大影响澳大利亚西岸降水,理解其在地质历史时期的变化及影响因素,对于认识区域和全球气候变化具有重要意义。本次研究将鲁汶流区采集的SO18588孔岩芯上部63 cm沉积物作为研究材料,并以1 cm为间隔对其进行采样,共计获得63个沉积物样品。通过对这些沉积物样品进行研究,发现在SO18588站处浮游有孔虫热带表层水种Trilobatus sacculifer的相对丰度比浮游有孔虫热带-亚热带表层水种Globigerinoides ruber的相对丰度更适合被用于指示鲁汶流强度变化;之后,利用浮游有孔虫热带表层水种T.sacculifer的相对丰度,重建了32 ka B. P.以来鲁汶流的强度变化,并与已发表的古海洋和古气候学记录进行了对比。结果显示,鲁汶流强度的冰期-间冰期变化受海平面升降和类厄尔尼诺-南方涛动气候态共同调控:冰期时海平面下降,类厄尔尼诺态强化,导致鲁汶流减弱;间冰期时,海平面上升,类拉尼娜态发育,造成鲁汶流增强。9.5~0 ka B. P.期间,鲁汶流强度的持续弱化,可能归因于澳洲冬季风的减弱和早全新世类拉尼娜格局向现代类厄尔尼诺格局转变所造成的厄尔尼诺事件频发;9.5 ka B. P.左右鲁汶流强度事件性地突然减弱,可能与海平面上升所导致的卡里马塔海峡贯通、印尼穿越流表层流被抑制有关。
基金Supported by the National Natural Science Foundation of China(Nos.40706033 and 40806031)COMRA Program(Nos.DYXM-115-02-1-12 and DY115-01-2-5)
文摘During the 134 （1996 1997） and the 19th （2002-2003） Chinese National Antarctica Research Expeditions, we collected 60 discrete surface seawater samples along the cruise from the Chanjiang River （Yangtze） estuary （30^.59%, 122^.26＇E） through Taiwan Strait, the South China Sea, and the Eastern Indian Ocean to Prydz Bay, Antarctica （69^.10＇S, 74^.30＇E）, and analyzed them for the 226Ra specific activity. The 226Ra specific activity of the Chanjiang River estuary surface water （3.15 Bq/m3） was found to be the highest among all the surface samples because of the desorption of 226Ra from riverine particles. Between Chanjiang River estuary and 40^.S, 226Ra specific activity was found to be relatively uniform with a mean value of 1.07 Bq/m3 （n= 19, SD=0.14）, similar to that of the open ocean. From 40^.S to 65^.S, 226Ra specific activity increased intensively, then decreased moderately further southwards. Near the Antarctic shore, it increased again, to 2.31 Bq/m3. This distribution was controlled by a combination of deep water upwelling, Southern Ocean fronts, water mixing and the continental 226Ra import. In Prydz Bay and the adjacent sea area, the mean 226Ra activity value was 2.26 Bq/m3 （n=31, SD=0.28）, with a relatively higher value outside of the bay and low 226Ra activity value in the center of the bay. This was consistent with the topography and hydrological setting of the bay. In addition, we extended the study area northward to the Arctic, by combining the published Z26Ra dataset for surface water from the Bering Sea to the Japan Sea. We also discuss the 226Ra distribution of high latitude oceanic surface water and its mechanisms.
基金supported by Strategic Research Fund for Marine Environment
文摘Along the downwelling coast off Western Australia, late-austral-autumn/early-austral-winter chlorophyll a blooms are observed on the continental shelf south of the Shark Bay (26° S). The late-austral-autumn/early-austral-winter blooms are in phase with seasonal strengthening of the Leeuwin Current and its eddy field. From satellite altimeter and ocean color data , anticyclonic eddies are found to entrain the high phytoplankton biomass waters from the shelf and transport them offshore into the oligotrophic, subtropical marine environment. The late-austral-autumn/early-austral-winter blooms are highly linked with enhanced horizontal mixing by mesoscale eddies in the region, as derived from the finite-size Lyapunov exponent (FSLE) of the surface geostrophic flow field obtained from satellite altimeter data. The pathways of cross-shelf exchanges, which are mostly driven by the mesoscale eddies, are revealed with coalescing of the FSLE of the surface geostrophic flow field and the satellite chlorophyll a images.
