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1.
《海洋预报》2017,(3)
利用在北太平洋海域(120°E~100°W,10°~60°N;)19a间(1993—2011年)识别追踪出的中尺度涡,结合该区域内的Argo浮标资料,初步探索了北太平洋不同区域之间涡旋垂直温度结构的差异性。通过对比北太平洋4个小区域(副热带逆流区域、黑潮延伸体区域、亲潮区域、东部加利福尼亚沿岸区域)内的涡旋发现:每个区域内气旋涡和反气旋涡的垂直温度结构具有很大的相似性,但不同区域之间则略有差异。其中黑潮延伸体区域跟其它区域的中尺度涡垂直温度结构有较大差别,该区域内中尺度涡温度异常值明显大于其它区域,冷暖核的深度比其它区域要深,并且从100~600 m的深度上都有较大的温度异常。 相似文献
2.
本文使用基于热成风速度的涡旋识别拓展方法,通过海表面温度数据对黑潮延伸体区域50~100 km涡旋进行研究,发现50~100 km涡旋主要分布在黑潮延伸体流轴两侧,气旋涡和反气旋涡的寿命、半径分布具有一致性。气旋涡多出现在35°N以北,反气旋涡在35°N以南比较集中,与尺度较小的中尺度涡旋分布特征较为相似。冬夏两季涡旋地理分布存在一定差异,主要与不同季节该区域海表温度梯度及风应力旋度的变化有关。35°N以南50~100 km涡旋数量的季节性变化与风速大小的季节性变化存在明显的正相关性。35°N以南50~100 km涡旋三倍半径内风速异常和风应力旋度归一化表明,气旋涡对应风速负异常而反气旋涡对应风速正异常,反气旋涡的产生依赖于风应力负旋度,气旋涡的生成与风应力正旋度有关。 相似文献
3.
基于1993—2017年从卫星高度计资料中识别出来的中尺度涡轨迹数据集,对冬、夏季孟加拉湾涡旋的源地和性质进行了研究。研究表明孟加拉湾西部、安达曼海和孟加拉湾通往赤道的出口处的中尺度涡旋活动呈现显著的季节性差异。安达曼海在冬、夏季从北往南中尺度涡旋分别以“反气旋涡-气旋涡-反气旋涡”和“气旋涡-反气旋涡-气旋涡”的格局分布。不同源区涡旋的季节性生长过程有明显差异。孟加拉湾西部的涡旋在夏季生长迅速但消散缓慢,斯里兰卡冷涡生长缓慢但消散迅速。不同源区涡旋半径和振幅大小有不同的特征。孟加拉湾西部,无论冬、夏季,反气旋涡的振幅、半径都比气旋涡大;夏季季风漂流区,气旋涡半径比反气旋涡小但是振幅比反气旋涡大;安达曼海内无论冬、夏季都是最北侧聚集区涡旋的半径和振幅最大。孟加拉湾内生命史为30~40 d的涡旋数量最多,生命史在100 d以上的涡旋主要分布在孟加拉湾西部。 相似文献
4.
基于1993-2014年高度计数据的西北太平洋中尺度涡识别和特征分析 总被引：4，自引：4，他引：0
本文利用22年的AVISO卫星高度计融合数据,基于WA涡旋自动识别方法对西北太平洋的中尺度涡进行了识别追踪,并统计分析了研究区域中尺度涡的空间分布特征、运动属性以及季节和年际变化。研究结果表明:22年间共追踪到生命周期超过30 d的气旋涡3 841个,反气旋涡2 836个,气旋涡数量多于反气旋涡。涡旋大部分向西移动,西向传播的涡旋分布在整个研究区域,而东向传播的涡旋则集中在黑潮及其延伸区。涡旋主要存在15°~30°N的纬度带间;分别而言,气旋涡主要分布在研究区域的北部和南部,而反气旋涡主要分布在副热带逆流区。30°~35°N之间的黑潮延伸区具有明显更高的涡动能和涡振幅,与同纬度区域相比这里的涡旋半径也较高。在季节和年际变化上,春季出现的中尺度涡最多,夏季最少;对涡旋的月生成数目与ENSO指数MEI比较发现,西北太平洋涡旋活动变化并不直接与ENSO现象相关。 相似文献
5.
采用AVISO提供的中尺度涡最新数据集,分析了孟加拉湾1993—2016年中尺度涡的总体特征和季节变化。结果表明:研究期间在孟加拉湾共有822个气旋涡,731个反气旋涡,主要分布在湾北部(15°N以北海域)和安达曼海。涡旋生命周期以28～59 d为主,平均振幅为7. 5 cm,平均半径为119. 6 km。在纬度变化上,涡旋振幅随纬度的增加有两个峰值,分别位于6°～9°N和15°～20°N之间,而涡旋半径随纬度增加而减少。涡旋的振幅、半径在随生命周期演变过程中生长过程较慢,消散过程较快。气旋涡和反气旋涡主要是向西移动,且均以向赤道方向偏移为主。在季节变化上,孟加拉湾较长生命周期(60 d以上)的中尺度涡具有明显的季节变化,春季生成的涡旋数量最多,冬季次之,夏季最少。通过合成分析得出风应力旋度是孟加拉湾中尺度涡季节变化的主要原因,而沿岸Kelvin波激发的西传Rossby波对涡旋的产生也有一定影响。涡动能分析表明,涡动能的高值区主要位于海盆的西边界和斯里兰卡东部海域,同时,在冬季、春季海盆的西边界和夏季、秋季海盆的北部涡旋活动较多的区域对应着较大的涡动能。 相似文献
6.
本文使用基于热成风速度的涡旋识别拓展方法,通过海表面温度数据对黑潮延伸体区域50-100公里涡旋进行研究,发现50-100公里涡旋主要分布在黑潮延伸体流轴两侧,气旋涡和反气旋涡的寿命、半径分布具有一致性。气旋涡多出现在35°N以北,反气旋涡在35°N以南比较集中,与尺度较小的中尺度涡旋分布特征较为相似。冬夏两季涡旋地理分布存在一定差异,主要与不同季节该区域海表温度梯度及风应力旋度的变化有关。35°N以南50-100公里涡旋数量的季节性变化与风速大小的季节性变化存在明显的正相关性。35°N以南50-100公里涡旋三倍半径内风速异常和风应力旋度归一化表明,气旋涡对应风速负异常而反气旋涡对应风速正异常,反气旋涡的产生依赖于风应力负旋度,气旋涡的生成与风应力正旋度有关。 相似文献
7.
黑潮延伸体邻近区域中尺度涡特征统计分析 总被引：7，自引：3，他引：4
本文利用20年的卫星高度计资料,对黑潮延伸体邻近海区(25°—45°N,135°E—175°W)中尺度涡的统计特征以及季节变化进行了统计研究。基于涡旋自动识别方法,共识别出本区域3006个气旋涡轨迹和2887个反气旋涡轨迹,其平均周期分别为9.99周和11.00周,平均半径分别为69.5km和71.8km。长生命周期涡旋的平均半径、涡度、涡动能(EKE)和涡旋能量密度(EI)在生命周期内大致都经历了增大-基本保持不变-减小这三个阶段。绝大多数涡旋沿纬线向西移动,经向移动距离较小,气旋涡和反气旋涡在西向传播过程中都具有明显的向南(赤道)偏离趋势。涡旋的生成数量与总数量均在春夏季达到最多,且这一时期涡旋的平均涡度、EKE、EI处于较高水平。 相似文献
8.
基于1993-2012年Aviso海面高度异常资料识别中尺度涡,计算南海海域涡动能比,并结合涡旋移动轨迹对气旋涡、反气旋涡的时空分布特征进行分析。结果表明,涡动能比能直观刻画区域涡旋活跃程度,结合涡旋移动轨迹后能有效反映涡旋演变过程。冬季季风期,南海中尺度涡最为活跃,反气旋涡、气旋涡交错分布在南海东部。台湾岛西南反气旋涡大多向西北方向移动,少数在气旋涡作用下向西南方向移动。越南东部涡旋呈偶极子分布,夏秋季北部是气旋涡,南部是反气旋涡,冬季北部是反气旋涡,南部是气旋涡。 相似文献
9.
本研究通过OW（Okubo Weiss）参数和闭合等值线相结合的方法自动识别西北太平洋（0°—45°N,120°—180°E）中尺度涡并跟踪后续中尺度涡,分析了不同寿命中尺度涡的季节变化、年际变化、数量特征以及动力学参数等。研究发现,不同寿命中尺度涡的数量高峰时间在不同程度上晚于气象上最冷月份约1~3个月。与其他寿命中尺度涡不同,中等寿命中尺度涡的气旋涡（33.9 cm/s）比中等寿命中尺度涡的反气旋涡（16.9 cm/s）旋转得更快,季节变化最为显著。冬季更适于西北太平洋中尺度涡的发生与发展,并且在寿命上,更易发展为中等寿命涡旋。不同寿命中尺度涡的月数量变化都存在3个明显的周期性变化（第一主周期、第二主周期、第三主周期）,根据不同主周期的时间尺度长短,它们的影响因子分别可能是太阳辐射、ENSO现象、季节变化。从地理分布看,不同寿命中尺度涡高频区分布并不完全一致。从涡旋平均振幅地理分布看,中等寿命中尺度涡在高频区拥有最大的涡旋平均振幅（15~25 cm）,短寿命中尺度涡次之（15~20 cm）,长寿命中尺度涡的平均振幅最小（10~16 cm）。从涡旋半径地理分布看,长寿命中尺度涡仅在副热带逆流区有较大的平均半径（20~30 km）,中等、短寿命中尺度涡在研究区域北部均有着较大的平均半径（30~45 km）。从动力学参数看,西北太平洋中尺度涡的动力学参数在寿命中期并非是最高值,约在寿命的前三分之一达到第一个高值,然后小幅下降,保持稳定,直到寿命的后三分之一小幅上升,达到第二个高值,然后迅速下降直至数值为零。 相似文献
10.
南印度洋中尺度涡统计特征及三维合成结构研究 总被引：2，自引：2，他引：0
南印度洋是海洋中尺度涡的多发区域。本文利用卫星高度计资料及Argo浮标资料,对南印度洋（10°~35°S, 50°~120°E）区域中尺度涡的分布、表观特征等进行了统计分析,采用合成方法,构建了该区域中尺度涡的三维温盐结构。结果表明,涡旋频率呈明显的纬向带状分布,在18°~30°S存在一个明显的涡旋频率带状高值区;涡旋半径具有由南至北逐渐增大的趋势;长周期涡旋在其生命周期内,半径、涡动能、涡能量密度、涡度等性质均经历了先增大而后减小的过程;涡旋以西向运动为主,在经向上移动距离较小,长周期气旋（反气旋）涡具有明显的偏向极地（赤道）移动的倾向;涡旋平均移动速度为5.9 cm/s,速度大小大致沿纬向呈带状分布。在混合层以下,气旋涡（反气旋涡）内部分别呈现明显的温度负（正）异常,且分别存在两个位温负（正）异常的冷（暖）核结构;气旋涡（反气旋涡）整体上呈现"正-负"（"负-正"）上下层相反的盐度异常结构。中尺度涡对温盐的平均影响深度可达1 000×104 Pa以上。 相似文献
11.
综述东海和琉球群岛以东海域若干气旋型和反气旋型涡旋的研究.对东海陆架、200m以浅海域,主要讨论了东海西南部反气旋涡、济州岛西南气旋式涡和长江口东北气旋式冷涡.东海两侧和陆坡附近出现了各种不同尺度的涡旋,其动力原因之一是与东海黑潮弯曲现象有很大关系,其次也与地形、琉球群岛存在等有关.东海黑潮有两种类型弯曲:黑潮锋弯曲和黑潮路径弯曲.黑潮第一种弯曲出现了锋面涡旋,评述了锋面涡旋的存在时间尺度与空间尺度和结构等;也指出了黑潮第二种弯曲,即路径弯曲时在其两侧出现了中尺度气旋式和反气旋涡,讨论了它们的变化的特性.特别讨论了冲绳北段黑潮弯曲路径和中尺度涡的相互作用,着重指出,当气旋式涡在冲绳海槽北段成长,并充分地发展,其周期约在1~3个月时,它的空间尺度成长到约为200km(此尺度相当于冲绳海槽的纬向尺度)时,黑潮路径从北段转移到南段.也分析了东海黑潮流量和其附近中尺度涡的相互作用.最后指出在琉球群岛以东、以南海域,经常出现各种不同的中尺度反气旋式和气旋式涡,讨论了它们在时间与空间尺度上变化的特征. 相似文献
12.
《African Journal of Marine Science》2013,35(3):343-350
This paper describes the westward movement of a cyclonic eddy across the Mozambique Channel and the subsequent south-westward propagation of the eddy along the east coast of South Africa and its interaction with the shelf. A hydrographic survey on 13 September 2006 off Nine-mile Reef (NMR), Sodwana Bay, showed a well-developed Agulhas Current along the continental shelf inshore of a cyclonic eddy flanked by two anti-cyclonic eddies, further offshore. A satellite-tracked drifter and complementary altimetry data confirmed the dimensions of the eddy and tracked its movement towards the coast. Shelf-edge upwelling was measured at NMR by an underwater temperature recorder (UTR) when the cyclonic eddy first came into contact with the shelf and again when the cyclonic eddy interacted with the leading edge of the anti-cyclonic eddy moving onto the shelf. Further shelf–eddy interactions off Aliwal Shoal, south of Durban, and consequent upwelling were similarly caused by the same cyclonic eddy as it progressed south-westward along the east coast. Analysis of UTR data between 2004 and 2006 indicated that between two and five cyclonic eddies impact the shelf off NMR per year. 相似文献
13.
利用南海20 a逐日海流再分析资料对南海海域中尺度涡进行时空特征分析。经过数据处理、涡漩识别、统计分析等方法,对南海海域中尺度涡空间分布、时间分布、生命周期、空间尺度、移动路径、移动速度、影响频率等特征进行分析,对南海中尺度涡进行全面详细的解读。研究发现:涡旋出现位置跟南海200 m等深线较一致。大部分涡旋周期都集中在30 d以内,直径大都在100~300 km,主要向西南方向移动,速率在15~20 cm/s的涡旋比例最高。反气旋式中尺度涡影响频率要大于气旋式中尺度涡的影响频率,主要影响区域大致在200 m等深线以内海域。 相似文献
14.
Zooplankton community structure in a cyclonic and mode-water eddy in the Sargasso Sea 总被引：1，自引：0，他引：1
Bethany R. Eden Deborah K. Steinberg Sarah A. Goldthwait Dennis J. McGillicuddy Jr. 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(10):1757-1776
Mesoscale eddies are important suppliers of nutrients to the surface waters of oligotrophic gyres, but little is known about the biological response, particularly that of higher trophic levels, to these physical perturbations. During the summers of 2004 and 2005, we followed the development of a cyclonic eddy and an anti-cyclonic mode-water eddy in the Sargasso Sea. Zooplankton (>150 μm) were collected across both eddies in 9 discrete depth intervals between 0 and 700 m. Comparison of the abundance of major taxa of mesozooplankton in the upper 150 m at eddy center and outside the eddies (day and night) indicated that the cyclone and mode-water eddy supported similar mesozooplankton communities, with several taxa significantly higher in abundance inside than outside the eddies, when compared with the Bermuda Atlantic Time-series Study site as representative of mean conditions. In both eddies copepod peak abundance occurred in the 50-100 m depth interval, coincident with the chlorophyll a maximum, suggesting elevated food concentration in the eddies may have influenced zooplankton vertical distribution. The two eddies differed in the strength of diel vertical migration of zooplankton, as indicated by the ratio of night:day abundance in the epipelagic zone, which was higher at the center of the mode-water eddy for most taxa. Over the sampling interval of 1-2 months, abundance of the three most common taxa (copepods, chaetognaths, and ostracods) decreased in the cyclone and increased in the mode-water eddy. This further supports previous findings that over the sampling period the cyclone was in a decay phase, while the mode-water eddy was sustaining nutrient fluxes and high phytoplankton concentrations. A more detailed analysis of community structure in the mode-water eddy indicated the 0-700 m integrated abundance of doliolids was significantly higher inside the mode-water eddy than outside. The presence of a mesopelagic (200-700 m) layer of lepadid barnacle cyprids in this eddy highlights the potential of eddies to transport and disperse biota. We conclude that when compared with average ambient conditions (as measured at BATS), mesoscale eddies can influence zooplankton behavior and alter zooplankton community structure which can affect food-web interactions and biogeochemical cycling in the open ocean. 相似文献
15.
The statistical characteristics and vertical thermohaline properties of mesoscale eddies in the Bay of Bengal are studied from the view of satellite altimetry data and Argo profiles. Eddy propagation preferences in different lifetimes, eddy evolution process, and geographical distribution of eddy kinetic properties are analyzed in this area. Eddies exist principally in the western Bay of Bengal, and most of them propagate westward. There is a clear southward(equatorward) preference for eddies with long lifetimes, especially for cyclones. Moreover, the eddies in different areas of the bay show different north-southward preferences. Evolution of eddy kinetic properties with lifetime shows that eddies have the significant three-stage feature: the growth period in the former one-fifth lifetime, the stable period in the middle two-fifth to four-fifth lifetime, and the dying period in the last one-fifth lifetime. Large-amplitude and high-intensity eddies occur only in the relatively confined regions of highly unstable currents, such as the East Indian Coastal Current and eastern Sri Lanka. Based on Argo profile data and climatology data, the eddy synthesis method was used to construct three-dimensional temperature and salt structures of eddies in this area. The mean temperature anomaly is negative/positive to the cyclonic/anticyclonic eddies in the upper 300×10~4 Pa, and below this depth, the anomaly becomes weak. The salinity structures of positive anomalies inside cyclonic eddies and negative anomalies inside anticyclonic eddies in the Bay of Bengal are not consistent with other regions. Due to the special characteristics of the water mass in the bay, especially under the control of the low-salinity Bay of Bengal water at the surface and the Indian equatorial water in the deep ocean, the salinity of seawater shows a monotonic increase with depth. For regional varieties of temperature and salinity structures, as the eddies move westward, the temperature anomaly induced by the eddies increases, the effecting depth of the eddies deepens, and the salinity structures are more affected by inflows. In the north-south direction, the salinity structures of the eddies are associated with the local water masses, which comprise lowsalinity water in the northern bay due to the inflow of freshwater from rivers and salty water in the southern bay due to the invasion of Arabian Sea high-salinity water from the north Indian Ocean. 相似文献
16.
On the basis of hydrographic data obtained from 12 June to 6 July, 1998, the three-dimensional structure of circulation in
the South China Sea (SCS) is computed using a three-dimensional diagnostic model. The combination of sea surface height anomaly
from altimeter data and numerical results provides a consistent circulation pattern for the SCS, and the main circulation
features can be summarized as follows: In the northern SCS there are a cyclonic eddy C1 near Dongsha Islands and an anti-cyclonic
eddy W1 west of Luzon Island. In the central SCS a strong anti-cyclonic eddy W3 and a cyclonic eddy C3 compose a quasi-dipole
southeast of Vietnam. A coastal northward jet is present at the western boundary near the Vietnam coast above 300 m level.
This northward coastal jet flows northward and turns eastward at about 14°N, and then flows southeastward into the area between
eddies W3 and C3. In the southern SCS the current is weaker. The most important dynamic mechanism underlying the circulation
in the SCS is the joint effect of the baroclinicity and relief (JEBAR), and the second dynamical mechanism is the interaction
between the wind stress and relief (IBWSR). Comparison of the characters of circulation in the SCS during summer 2000 with
that during summer 1998 reveals no obvious variability of the main characteristics. 相似文献
17.
Three dimensional diagnostic modeling study of the South China Sea circulation before onset of summer monsoon in 1998 总被引：1，自引：0，他引：1
The wind data from NCEP and hydrographic data obtained from April 22–May 24, 1998 have been used to compute the circulation
in the South China Sea (SCS) using three dimensional diagnostic models. The main numerical results with SSHA derived from
T/P altimeter are as follows: most of intruded Kuroshio bypasses. However, a part of Kuroshio intrudes westward above 300
m levels. This intruded westward flow is narrowly confined to the continental slope south of China, in agreement with the
findings of Qu et al. (2000). The basin-scale cyclonic gyre dominates in the northern SCS and consists of two cyclonic eddies, C2 and C3, above
300 m levels. However, it is separated into two parts by an anti-cyclonic eddy, W4, below 300 m. The basin-scale anti-cyclonic
gyre dominates in the central SCS and consists of three anti-cyclonic eddies, W1, W2 and W3, above 300 m levels. However,
below 300 m it consists of the anti-cyclonic eddies W1, W2 and W4 and extends northward to near 20°N. A northward coastal
jet is present near the coast of Vietnam at depths above 300 m, and develops northward further to about a distance of 3°15′
N than that in cruise 2. The most important dynamical mechanism is due to the joint effect of the baroclinity and relief.
The second dynamical mechanism is due to the interaction between the wind stress and relief. The topography effect is more
important than the β effect. The Sverdrup relation cannot be satisfied in the SCS. 相似文献
18.
The role of meso-scale eddies in mixed layer deepening and mode water formation in the western North Pacific 总被引：3，自引：1，他引：2
Shinya Kouketsu Hiroyuki Tomita Eitarou Oka Shigeki Hosoda Taiyo Kobayashi Kanako Sato 《Journal of Oceanography》2012,68(1):63-77
Distributions of mixed layer depths around the centers of anti-cyclonic and cyclonic eddies in the North Pacific Ocean were
composited by using satellite-derived sea surface height anomaly data and Argo profiling float data. The composite distributions
showed that in late winter, deeper mixed layers were more (less) frequently observed inside the cores of the anti-cyclonic
(cyclonic) eddies than outside. This relationship was the clearest in the region of 140°E–160°W and 35°N–40°N, where the temperature
and salinity of the deep mixed layers were similar to those of the lighter variety of central mode water (L-CMW). A simple
one-dimensional bulk mixed layer model showed that both strong sea-surface heat and momentum fluxes and weak preexisting stratification
contributed to formation of the deep mixed layer. These conditions were associated with the anti-cyclonic eddies, suggesting
that these eddies are important in the formation of mode waters, particularly L-CMW. 相似文献
19.
2000年8月南海中部与南部海洋温、盐与环流特征 总被引：13，自引：2，他引：11
根据2000年8—9月份南海中部与南部航次的温、盐资料,采用P—矢量诊断方法,结合ADCP测流资料和同期伪风应力资料以及TOPEX／Poseidon高度计资料,研究了2000年夏季风持续强迫之后南海大尺度环流与中尺度涡旋的空间结构。结果表明,南海夏季温度和盐度水平分布随深度有显著的变化：中层(250—400m左右)温、盐水平分布与其它各层的温度和盐度分布相比有很大的差异。用诊断方法计算得到的环流场与用TOPEX／Poseidon海面高度计资料计算得到的地转流场比较一致,即流场内部有多个中尺度的涡旋,主要有越南东南外海反气旋涡、中沙群岛东南反气旋涡以及南沙群岛东北角的气旋涡等,这说明南海中部与南部盛夏环流具有较强的地转分量和显著的多涡结构,并且这些中尺度涡在垂向上存在速度场的切变。 相似文献
20.
The transition zone of the Canary Current upwelling region 总被引：2，自引：0，他引：2
E. D. Barton J. Arístegui P. Tett M. Cantn J. García-Braun S. Hernndez-Len L. Nykjaer C. Almeida J. Almunia S. Ballesteros G. Basterretxea J. Escnez L. García-Weill A. Hernndez-Guerra F. Lpez-Laatzen R. Molina M. F. Montero E. Navarro-Prez J. M. Rodríguez K. van Lenning H. Vlez K. Wild 《Progress in Oceanography》1998,41(4):455-504
Like all the major upwelling regions, the Canary Current is characterised by intense mesoscale structure in the transition zone between the cool, nutrient-rich waters of the coastal upwelling regime and the warmer, oligotrophic waters of the open ocean. The Canary Island archipelago, which straddles the transition, introduces a second source of variability by perturbing the general southwestward flow of both ocean currents and Trade winds. The combined effects of the flow disturbance and the eddying and meandering of the boundary between upwelled and oceanic waters produce a complex pattern of regional variability. On the basis of historical data and a series of interdisciplinary field studies, the principal features of the region are described. These include a prominent upwelling filament originating near 28°N off the African coast, cyclonic and anti-cyclonic eddies downstream of the archipelago, and warm wake regions protected from the Trade winds by the high volcanic peaks of the islands. The filament is shown to be a recurrent feature, apparently arising from the interaction of a topographically trapped cyclonic eddy with the outer edge of the coastal upwelling zone. Its role in the transport and exchange of biogenic material, including fish larvae, is considered. Strong cyclonic eddies, observed throughout the year, drift slowly southwestward from Gran Canaria. One sampled in late summer was characterised by large vertical isopycnal displacements, apparent surface divergence and strong upwelling, producing a fourfold increase in chlorophyll concentrations over background values. Such intense eddies can be responsible for a major contribution to the vertical flux of nitrogen. The lee region of Gran Canaria is shown to be a location of strong pycnocline deformation resulting from Ekman pumping on the wind shear boundaries, which may contribute to the eddy formation process. 相似文献