共查询到19条相似文献，搜索用时 176 毫秒
1.
《热带海洋学报》2016,(5)
以2006—2013年卫星遥感海表温度资料(GHRSST SST)为基础,通过数字图像处理的边缘检测方法提取温度锋面的核心位置,分析了琼东、粤西海域海表温度锋位置及强度的季节变化和年际变化特征,并进一步结合海面高度异常资料和海面风场资料探讨了温度锋变化的可能机制。分析结果表明,琼东、粤西海域温度锋的空间分布及锋面强度存在显著的季节变化,沿岸风应力是影响该海域锋面变化的主要动力因素。夏季温度锋面主要分布于琼东沿岸的东部及南部海域近岸50m到100m等深线之间,而冬季则主要分布在琼东的东部海域和粤西沿岸20m到100m等深线之间,春秋两季为其过渡季节;锋面强度的季节变化表现为冬季最强,春季、夏季次之,秋季最弱,其冬季锋面强度平均值可达到3℃?100km–1,夏季为1.7℃?100km–1;同时,锋面核心位置及强度的分析结果表明,琼东和粤西海域温度锋也存在较强的年际变化。 相似文献
2.
基于WOA13的温盐数据资料,利用绝对梯度分析法,对太平洋赤道海区的温度、声速锋面的时空分布特征进行了分析,结果表明,3种要素的锋面均存在于一南一北两个位置。温度锋面:北赤道温度锋面全年均存在,锋面位置主要分布在7°N、水深30~200 m处,锋面随深度加深逐渐向西移动,秋季锋面分布范围最广且锋强度最大,春季锋面分布范围最小且锋强度最小。南赤道温度锋面全年存在,锋面位置主要分布在5°S、水深50~275 m处。随深度加深,锋面也逐渐向西移动且东西跨度变长。春季锋的强度最大,秋季的锋强度最弱。声速锋面:声速锋与温度锋的位置大致相同,且两者在锋轴线上同一点处的锋强度的相关系数接近于1,可见温度对声速的影响很大。此外,最大声速锋强出现在水深100 m处。 相似文献
3.
基于2000-2017年的MODIS-Terra气候态月平均海表温度数据检测了东印度洋季风带海域的温度锋,统计了各锋面每月发生的锋点数量、锋面平均强度及中心线长度,并基于2000—2017年逐年海表温度数据,研究了以恒河-雅鲁藏布江河口锋和爪哇岛锋为代表的典型温度锋面的年际变化。结果发现:在3、4月,东印度洋季风带海域的锋面最弱、数量最少;5-10月期间,5°~15°N及5°~15°S一带的温度锋出现并发展;12、1、2月最北部锋面发展并趋向成熟。研究区存在恒河-雅鲁藏布江河口锋、爪哇岛锋、Palk海峡锋、东锡兰锋及伊洛瓦底江河口锋5个温度锋,其中最北部的恒河-雅鲁藏布江河口锋全年存在,东北季风时期长度较长,强度较大,最南部的爪哇岛锋存在于4—11月,西南季风时期较强,长度和数量也处于较高水平,其余锋面主要发生于西南季风盛行时期,且强度、长度等变化相对较小。两个典型温度锋空间位置的年际变化均不大,恒河-雅鲁藏布江河口锋平均强度的年际变化较大,最大超过0.03℃/km,长度变化相对较小;爪哇岛锋平均强度的变化相对平稳,但锋点数量和中心线长度存在较大的年际变化。 相似文献
4.
采用海洋再分析结果,研究了海洋涡旋和锋面波动对台湾以东黑潮锋的影响,结果表明,Rossby波第一斜压模态形成的冷涡(暖涡),减弱(增强)台湾以东黑潮温度锋强度,减小(加大)锋的宽度.在再分析结果中,捕获到1991年1-2月台湾以东的一次黑潮锋面波动.锋面波动的波槽(波脊)到达时,该温度锋强度减弱(增强),宽度和厚度减小... 相似文献
5.
6.
本文利用近十年来获得的ＮＯＡＡ卫星红外影像，较为系统地分析了东海海洋锋（黑潮锋、对马暖流锋和浙江沿岸锋）的波动谱特征以及形态的演变。同时还利用浮标测流结果分析了锋面波动中的流态。分析结果表明：东海黑潮锋通常存在４～５个折叠波形，其波长平均约２００ｋｍ，波动随黑潮流向东北方向传播，速度约１６ｃｍ／ｓ。浙江沿岸锋的波动多呈锯齿形，其波长较短，波数多。在浙江沿岸锋波动发展过程中，其波长从开始的２０～４０ｋｍ发展成３０～６０ｋｍ，它们约以１８ｃｍ／ｓ的速度向东北方向传播。东海海洋锋波动演变形态复杂，其中黑潮锋的波动可能演变成锋面涡旋、暖丝和暖环。 相似文献
7.
在南大洋印度洋扇区中部海域,除了地形控制(凯尔盖朗高台),南极绕极流和厄加勒斯回流的汇合流进一步加强了下游的斜压剪切强度,导致涡旋能量显著增强,因此,对该海域涡旋的研究有助于了解该海域的涡旋特征以及地形与涡旋的分布关系。基于2005~2019年卫星遥感数据,对该海域涡旋特征进行统计,并对涡旋产生地分布、跨锋面涡旋的移动状况进行分析,同时结合Argo剖面数据,进一步剖析涡旋内部水文分布特征。结果表明:该海域涡旋生命周期多在20 d以内(64.25%),平均半径多在30~100 km(96.13%);平均半径与平均振幅呈正相关关系(相关系数R=0.55);生命周期越大的涡旋平均传播距离也越大。2014年开始涡旋数量明显增加,主要由短寿命涡旋(<30 d)数量增加所贡献。反之, 21世纪10年代后期年平均涡动能异常呈减小趋势。涡旋产生地随着寿命增长,逐渐从亚南极锋与南极绕极流南部边界之间的锋面区域向亚南极锋以北移动。跨锋面涡旋中,暖涡向高纬,冷涡向低纬移动,大部分具有携带水团移动的能力。由涡旋内部水文特征分析结果可知,不同极性的涡旋能够实现完全不同来源水团的远距离输送,对同一来源水团,气旋涡具有抬升作用,而反气旋涡具有压沉作用。该研究工作有助于提升对南大洋涡旋特征及变动的认识,为进一步的涡旋动力研究提供支撑。 相似文献
8.
9.
本文利用1987年1-2月中国第三次南极考察期间在南设得兰群岛邻近海域获得的STD资料,详细阐述了群岛以北海域中的一条海洋峰——大陆水边界(CWB)在表层、次表层和深层的表观特征,并给出了测区表面的地转流分布,计算了斜压变形半径Rbc.作者认为这里沿锋向海流处于地转平衡状态,且锋主要由边界流的作用所致.CWB的沿锋尺度约360km,平均宽度约30km. 相似文献
10.
利用高分辨率(1/18°)的POM(Princeton Ocean Model)模式数值模拟结果,结合观测数据分析了苏北浅滩外侧潮汐锋的季节分布特征和变化规律。研究结果表明,苏北浅滩外侧潮汐锋的季节变化特征显著,春末开始出现,夏季底层温度锋强度最大且锋区位置较稳定,锋区宽度约40 km,平均强度约0.35℃/km,秋、冬季随上层海洋湍流垂向混合的加强,潮汐锋逐渐减弱至消失不见。对比实测数据和模拟结果发现,沿34°N断面,夏季潮汐锋区附近等温线明显抬升,存在由陡峭地形和分层流体的内埃克曼效应共同作用形成的上升流现象。次表层海水出现低温冷水区,位于122.2°E附近。跨锋区断面的温度和流场分布特征同浅水区强烈的潮混合过程密切相关,斜压在锋面处产生了较强的南向流动。本研究结果促进了对苏北浅滩外侧陆架潮汐锋结构特征的认识,为研究黄海西部生态环境的动力过程影响提供参考。 相似文献
11.
Hydrographic data from the Iceland-Faeroes Ridge region, covering an area of 59°–69° north and 0°–20° west, have been subjected to a spatial data analysis. The analysis consists of the two-dimensional spectral method (2D-FFT) and the empirical eigenfunction method (EOF). Results from the two methods show good agreement indicating that the significant length scales for horizontal variability present in the data have wavelengths of approximately 339 km, 72 km and 37 km. These wavelengths relevant to the Iceland-Faeroes front are interpreted as the sizes respectively of the warm water intrusion from the south of the front with a diameter of half the wavelength (i.e.,?169 km), and the meander-like and eddy-like features. Predictions of the same frontal system have also been made using a realistic numerical model to provide hydrographic outputs similar to the observations. The hydrographic outputs from the model have been subjected to the same 2D-FFT method to establish the spatial length scale present in the model predictions. A comparison of results from a spectral data analysis between the field measurements and the model predictions shows that the model can predict the sizes of the meander-like and the eddy-like features quite accurately. However, predictions of frontal orientation, frontal slopes and size of the warm water intrusion still require further study. The work presented also demonstrates the importance of spatial statistics in oceanographic research, particularly in ocean predictability studies. 相似文献
12.
A. S. Kazmin 《Oceanology》2016,56(4):465-469
High-resolution satellite sea surface temperature measurements (PATHFINDER dataset) indicate that the fronts at the boundary of the East China Sea (Taiwan front, Kuroshio frontal zone, and South Korean coastal front) appear as a unified dominating frontal structure when climatological averaging is applied. This structure is about 1200 km in length, spreads over the continental shelf from Taiwan to the Tsushima Islands, and separates productive seawaters from the oligotrophic oceanic waters. The Kuroshio frontal zone, incorporated into this structure, reveals interannual variability with periods consistent with El Niño–Southern Oscillation (4–5 years). 相似文献
13.
-STD Data obtained from the Third Chinese National Antarctic Research Expedition from January to February 1987 in the region near the South Shetland Islands are used to investigate an oceanic front, continental water boundary (CWB), north of the South Shetland Islands. The characteristics of the CWB in surface and subsurface layers as well as deep layer are discussed respectively. The estimations of the geostrophic currents and the baroclinic deformed radius Rbc in this area show that the flow along the front is in the geostrophic equilibrium approximately, and the formation of the front is mainly due to the strong boundary current north of the South Shetland Islands. Its length along the front is estimated to be about 360 km and its width across the front is about 30 km. 相似文献
14.
To investigate the fluctuation of the Kuroshio front, moored current meters were deployed near the shelf break and on the continental slope in the East China Sea, northwest of Okinawa Island, during a period from 25 June to 22 July 1984. Two mooring arrays were deployed on the slope of about 800 m water depth (under the Kuroshio), about 30 km apart along the path of the Kuroshio. Another two arrays were set near the shelf break of about 300 m water depth. The fluctuation of current on the slope is found to have a predominant period of 11–14 days and a were length of 300–350 km, propagating toward the downstream direction of the Kuroshio with a phase velocity of about 30 cm sec?1. When the Kuroshio front approaches the shelf break and the crest of the meander covers the mooring site, the current direction moves toward the downstream direction of the Kuroshio and the water temperature increases. On the other hand, when the trough of the meander covers the mooring site, the current direction changes off-shoreward across the Kuroshio or in the upstream direction of the Kuroshio, and the water temperature decreases. Three-dimensional distributions of water temperature and salinity around the mooring site were observed with a CTD twice at 5.5 days intervals, which indicate the meanders of the front is about 180° out of phase. This coincides with a period of 11–14 days obtained with the moored current meters. Wave lengths of the dominant meander of the front in the satellite thermal images were about 350 km and 100–200 km, which also coincides with results obtained with the moored current meters. 相似文献
15.
Bin Wang Fuliang Lyu Shuang Li Jian Li Zhili Yang Li Li Xuefeng Wang Yintao Lu Taotao Yang Jingwu Wu Guozhong Sun Hongxia Ma Xiaoyong Xu 《海洋学报(英文版)》2021,40(3):84-93
High-resolution multichannel seismic data enables the discovery of a previous, undocumented submarine canyon(Huaguang Canyon) in the Qiongdongnan Basin, northwest South China Sea. The Huaguang Canyon with a NW orientation is 140 km in length, and 2.5 km to 5 km in width in its upper reach and 4.6 km to 9.5 km in width in its lower reach. The head of the Huaguang Canyon is close to the Xisha carbonate platform and its tail is adjacent to the central canyon. This buried submarine canyon is formed by gravity flows from the Xisha carbonate platform when the sea level dropped in the early stage of the late Miocene(～10.5 Ma). The internal architecture of the Huaguang Canyon is mainly characterized by high amplitude reflections, indicating that this ancient submarine canyon was filled with coarse-grained sediments. The sediment was principally scourced from the Xisha carbonate platform. In contrast to other buried large-scale submarine canyons(central canyon and Zhongjian Canyon) in the Qiongdongnan Basin, the Huaguang Canyon displays later formation time, smaller width and length, and single sediment supply. The coarse-grained deposits within Huaguang Canyon provide a good environment for reserving oil and gas, and the muddy fillings in Huaguang Canyon have been identified as regional caps. Therefore, Huaguang Canyon is potential area for future hydrocarbon exploration in the northwest South China Sea. Our results may contribute to a better understanding of the evolution of submarine canyons formed in carbonate environment. 相似文献
16.
The temporal variation of tidal-front sharpness (i.e., the maximal gradient of sea surface temperature (SST)) in Iyo-Nada,
Japan has been investigated using SST obtained by a commercial ferryboat. Tidal-front sharpness varies in time with a period
of 15 days. A numerical model approach was also adopted to investigate the temporal variation of frontal sharpness. The numerical
model, which contains a restoring term to express the tidal front reconstructed fortnightly by tides, reproduces the tidal
front accompanied by growing and/or decaying frontal waves. The amplitude of modeled frontal sharpness agrees well with the
observation. The amplitude of sharpness is much smaller than the observed value, unless frontal waves develop along the modeled
front. This therefore implies that tidal fronts are destroyed mainly due to growing frontal waves, and are restored fortnightly
at spring tides. We quantitatively evaluated the subsurface intrusion of seawater into the stratified region from the mixed
region by conducting passive-tracer experiments. We find that the cross-frontal transport with frontal waves is 4.9 times
larger than that without frontal waves. In addition, the cross-frontal transport reaches a long distance (about 25 km) because
of heton (mushroom)-type eddies developing along the front with frontal waves. 相似文献
17.
Characteristics and evolution of the Kuroshio frontal eddies and warm filaments are analyzed according to two series of satellite images (March 5 to 7, 1986 and April 14 to 16, 1988). The results show that the frontal eddies in the East China Sea are generated at the shelf break and move along the continental slope at a speed of 15 cm/s with the Kuroshio. The frontal eddies occur about every 10 d and evolve to be warm filaments a few hundred km in length and 30-40 km in width in the area west of the Yaku-shima. Meanwhile, the existence of the warm filament was also found in the area by analysing the hydrographic data in the area west of Kyushu during May 24-June 5, 1988.The Kuroshio warm filaments move westward opposite to the Kuroshio and then turn northward at the shelf break and become the main source of the warm water of the Tsushima Warm Current. A simple dynamic explanation for the process is presented in this paper. 相似文献
18.
《African Journal of Marine Science》2013,35(1):35-49
Mesoscale circulation features have been shown to play an important role in the cross-frontal mixing of upwelling cells, their frontal morphology and in their interaction with oceanic water masses. With three years of detailed thermal infra-red satellite information on the South-East Atlantic upwelling system available, it proved possible to present a preliminary study of four prevalent frontal features intrinsic to the short-term behaviour of upwelling in this area. Upwelling filaments are shown to extend between 50 and 600 km seawards of the main front and are found, as are upwelling plumes, predominantly off the recognized major upwelling cells. Frontal eddies have a range of diameters and are found distributed over the full area of upwelling and on both sides of the main upwelling front. Warm filaments of Agulhas Current origin are advected preferentially along the western border of the Agulhas Bank and follow closely the front of the southernmost upwelling cells, where they may play a catalytic role in the creation of frontal turbulence. 相似文献
19.
Microwave satellite images used for retrieving sea surface temperatures often have such distortions as noise and blurring of the thermal fronts. An image processing approach based on the Mumford-Shah model of optimal image approximation is considered for the solution to this problem. We divide images into flat areas and frontal zones, and then process these areas separately. Image fragmentation is based on automatic detection of the thermal front lines. SST enhancement in frontal zones is achieved by using image deconvolution methods. It has been shown that SST errors in high gradient areas reach 1–3 °C. The proposed approach can decrease this discrepancy. 相似文献