The eastern extent of the Barents–Kara ice sheet during the Last Glacial Maximum based on seismic-reflection data from the eastern Kara Sea     

Leonid Polyak  Frank Niessen  Valery Gataullin  & Valery Gainanov 《Polar research》2008,27(2):162-174

We present sub-bottom profiling (sparker and Parasound) results from the eastern Kara Sea, on the Eurasian Arctic margin, which enable the identification of the Last Glacial Maximum (LGM) ice extent. The analysed profiles show that glacigenic diamicton is ubiquitous at the seafloor, east of about 95°E and 78°N. The eastern margin of this diamicton is expressed in a conspicuous morainic ridge at the entrance to the Vilkitsky Strait, and to the south the diamicton projection aligns with the LGM limit mapped at the north-western Taymyr. The bottom of the Voronin Trough further north is also covered with diamicton and has numerous erosional bedforms, indicating a streamlined flow of grounded ice along the trough. Accurate dating of the diamicton is not attainable, but the correlation of pre-diamict sediments to well-dated sections in the Laptev Sea, and available ¹⁴C ages from sediments on top of the diamicton, indicate its LGM age. These results support the palaeogeographic reconstruction that assumes the extension of the LGM Barents–Kara ice sheet as far east as Taymyr. This configuration implies that LGM ice blocked the drainage of the Ob and Yenisey rivers on the Kara shelf. This inference is consistent with the presence of large (>100 km wide) lenses of basin infill adjacent to the southern margin of the diamicton. However, the limited distribution of the eastern Kara ice lobe, not extending on Severnaya Zemlya, suggests that the ice was fairly thin and short-lived: insufficient for the accumulation of the gigantic proglacial lakes that occurred during earlier glaciations.  相似文献   

Shallow water body data processing based on the seismic oceanography     

LIU Huaishan  HU Yi  YIN Yanxin  WANG Linfei  TONG Siyou  MA Hai 《中国海洋大学学报(英文版)》2013,12(3):319-326

Physical properties of sea water,such as salinity,temperature,density and acoustic velocity,could be demarcated through degradation of energy caused by water absorption,attenuation and other factors.To overcome the challenging difficulties in the quick monitoring of these physical properties,we have explored the high resolution marine seismic survey to instantly characterize them.Based on the unique wavefield propagating in the sea water,we have developed a new approach to suppress the noise caused by the shallow sea water disturbance and obtain useful information for estimating the sea water structure.This approach improves seismic data with high signal-to-noise ratio and resolution.The seismic reflection imaging can map the sea water structure acoustically.Combined with the knowledge of local water body structure profile over years,the instant model for predicting the sea water properties could be built using the seismic data acquired from the specially designed high precision marine seismic acquisition.This model can also be updated with instant observation and the complete data processing system.The present study has the potential value to many applications,such as 3D sea water monitoring,engineering evaluation,geological disaster assessment and environmental assessment.  相似文献   

Upper crustal structure under Jingtai–Hezuo profile in Northeastern Tibet from topography-dependent eikonal traveltime tomography          下载免费PDF全文

Ting Ma  Zhongjie Zhang  Peng Wang  Yingkang Li 《地震科学（英文版）》2014,27(2):137-148

The Northeastern Tibetan plateau records Caledonian Qilian orogeny and Cenozoic reactivation by continental collision between the Indian and Asian plates. In order to provide the constraint on the Qilian orogenic mechanism and the expansion of the plateau, wide-angle seismic data was acquired along a 430 km-long profile between Jingtai and Hezuo. There is strong height variation along the profile, which is dealt by topography flattening scheme in our crustal velocity structure reconstruction. We herein present the upper crustal P-wave velocity structure model resulting from the interpretation of first arrival dataset from topography-dependent eikonal traveltime tomography. With topography flattening scheme to process real topography along the profile, the evenness of ray coverage times of the image area (upper crust) is improved, which provides upper crustal velocity model comparable to the classic traveltime tomography (with model expansion scheme to process irregular surface). The upper crustal velocity model shows zoning character which matches with the tectonic division of the Qaidam-Kunlun-West Qinling belt, the Central and Northern Qilian, and the Alax blocks along the profile. The resultant upper crustal P-wave velocity model is expected to provide important base for linkage between the mapped surface geology and deep structure or geodynamics in Northeastern Tibet.  相似文献   

Meso-scale circulation at the intermediate-depth east of Mindanao observed by Argo profiling floats   总被引：1，自引：0，他引：1  

ZHOU Hui  YUAN DongLiang  GUO PeiFang  SHI MaoChong & ZHANG QiLong Key Laboratory of Ocean Circulation  Wave Studies  Chinese Academy of Sciences  Qingdao  China  Physical Oceanography Laboratory  Ocean University of China  Qingdao 《中国科学:地球科学(英文版)》2010,(3)

The meso-scale circulation at the intermediate depth east of Mindanao is studied using Argo profiling floats observations. The trajectories and the parking-depth velocities of Argo floats show that the intermediate-depth circulation east of Mindanao contains significant meso-scale features that are highly variable both in space and in time. Both cyclonic and anticyclonic eddies at the intermediate depth (1000–2000 m) are indicated by the trajectories east of Mindanao. The mean tangential velocities of these eddies are about 10 cm/s at 2000 m and over 20 cm/s at 1000 m, which indicates that the geostrophic calculation may contain large errors due to the vigorous eddy activity at the reference levels. The analyses also suggest that these eddies might play an important role in mass and vorticity balances of the intermediate-depth circulation east of Mindanao.  相似文献   

Fishery analysis using gradient-dependent optimal interpolation     

Chunling Zhang  Danyang Wang  Zhenfeng Wang 《海洋学报(英文版)》2022,41(2):116-126

The current lack of high-precision information on subsurface seawater is a constraint in fishery research. Based on Argo temperature and salinity profiles, this study applied the gradient-dependent optimal interpolation to reconstruct daily subsurface oceanic environmental information according to fishery dates and locations. The relationship between subsurface information and matching yellowfin tuna(YFT) in the western and central Pacific Ocean(WCPO) was examined using catch data from January 1...  相似文献   

应用Argo资料分析西北太平洋冬、夏季水团   总被引：1，自引：0，他引：1  

孙朝辉  许建平  刘增宏  童明荣  朱伯康 《海洋通报(英文版)》2008,10(2):1-13

应用Argo剖面浮标观测的温、盐度资料，分析了西北太平洋海域冬、夏季的温、盐度分布、水团结构及其分布。首先采用T-S点聚图法分析了该海域水团分布的基本情况，由点聚分析结果可知，该海域至少存在6种以上水团；再用模糊聚类软化法对水团作进一步划分，分别计算了该海域6至11类水团的F和△F值，结果表明，冬、夏季的△F值都以划分为8类时为最大，这与大洋水团的稳定性是一致的，因此，该海域冬、夏季水团以划分为8类最佳，它们分别是北太平洋热带表层水、北太平洋次表层水、北太平洋中层水、北太平洋副热带模态水、北太平洋深层水和赤道表层水，以及南太平洋次表层水和南太平洋中层水。  相似文献   

国际Argo计划执行现状剖析   总被引：1，自引：0，他引：1  

朱伯康  许建平 《海洋技术学报》2008,27(4)

国际Argo计划自2000年实施以来,世界上25个国家和团体已经在全球海洋中布放了5000余个Argo浮标,其中在海上正常工作的浮标已经超过3000个。这标志着全球Argo实时海洋观测网已经全面建成。文中将系统介绍国际Argo计划主要成员国在浮标布放、回收和Argo资料管理等方面所作出的贡献,以帮助读者对这21世纪的重大国际海洋观测计划有一较全面、深入的了解。  相似文献   

Mixed layer depth climatology of the North Pacific based on Argo observations   总被引：2，自引：1，他引：1  

Yuko Ohno  Naoto Iwasaka  Fumiaki Kobashi  Yoshiko Sato 《Journal of Oceanography》2009,65(1):1-16

A monthly mean climatology of the mixed layer depth (MLD) in the North Pacific has been produced by using Argo observations. The optimum method and parameter for evaluating the MLD from the Argo data are statistically determined. The MLD and its properties from each density profile were calculated with the method and parameter. The monthly mean climatology of the MLD is computed on a 2° × 2° grid with more than 30 profiles for each grid. Two bands of deep mixed layer with more than 200 m depth are found to the north and south of the Kuroshio Extension in the winter climatology, which cannot be reproduced in some previous climatologies. Early shoaling of the winter mixed layer between 20–30°N, which has been pointed out by previous studies, is also well recognized. A notable feature suggested by our climatology is that the deepest mixed layer tends to occur about one month before the mixed layer density peaks in the middle latitudes, especially in the western region, while they tend to coincide with each other in higher latitudes.  相似文献   

Argo floats revealing bimodality of large-scale mid-depth circulation in the North Atlantic   总被引：1，自引：1，他引：0  

CHU Peter C  IVANOV Leonid M  MELNICHENKO Oleg V  LI Rongfeng 《海洋学报(英文版)》2008,27(2):1-10

Analysis of Argo float trajectories at 1 000 m and temperature at 950 m in the North Atlantic between November 2003 and January 2005 demonstrates the existence of two different circulation modes with fast transition between them. Each mode has a pair of cyclonic - anticyclonic gyres. The difference is the location of the cyclonic gyre. The cyclonic gyre stretches from southeast to northwest in the first mode and from the southwest to the northeast in the second mode. The observed modes strongly affect the heat and salt transport in the North Atlantic. In particular, the second mode slows down the westward transport of the warm and saline water from the Mediterranean Sea.  相似文献   

Accuracy of the deep convection intensity from a limited number of casts     

《Dynamics of Atmospheres and Oceans》2020

Deep convection is one of the key components of the Atlantic Meridional Overturning Circulation. The intensity of deep convection (DC) is traditionally estimated as the maximum mixed layer depth (MMLD). In this study, we developed a criterion of the minimum number of casts needed for obtaining the MMLD in the Greenland Sea with a pre-defined accuracy. The criterion depends on convection intensity.For gridded datasets, we introduce a complementary measure for the DC intensity: the area of the region with the mixed layer depth over a predefined value (800 m for the Greenland Sea, notated as S₈₀₀). For a weak or a moderate DC, variations of its intensity is more clear from variations of the MMLD (cluster 1 in the MMLD - S₈₀₀ parameter space). Then the MMLD can be obtained with the 25 % accuracy for at minimum 40 casts during winter. For a well developed DC (cluster 2), variations of the DC intensity are better accessed from variations of S₈₀₀ and minimum 10 casts are required.In the central Greenland Sea, the number of casts is sufficient for obtaining the interannual variations of the convection intensity only since 1986. If only Argo floats are available, minimum 4 floats should simultaneously operate in the Greenland Sea gyre during winter to reach the abovementioned accuracy. Up to present, the number of floats has been insufficient during most of the winters.  相似文献