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1.
A new three-dimensional numerical model is derived through a wave average on the primitive N-S equations, in which both the＂Coriolis-Stokes forcing＂ and the＂Stokes-Vortex force＂ are considered. Three ideal experiments are run using the new model applied to the Princeton ocean model （POM）. Numerical results show that surface waves play an important role on the mixing of the upper ocean. The mixed layer is enhanced when wave effect is considered in conjunction with small Langmuir numbers. Both surface wave breaking and Stokes production can strengthen the turbulent mixing near the surface. However, the influence of wave breaking is limited to a thin layer, but Stokes drift can affect the whole mixed layer. Furthermore, the vertical mixing coefficients clearly rise in the mixed layer, and the upper ocean mixed layer is deepened especially in the Antarctic Circumpolar Current when the model is applied to global simulations. It indicates that the surface gravity waves are indispensable in enhancing the mixing in the upper ocean, and should be accounted for in ocean general circulation models. 相似文献
2.
采用POMgcs(Princeton Ocean Model with generalized coordinate system)和MITgcm(MIT General Circulation Model)两个海洋数值模式,研究了M-Y2.0、基于固壁近似假定的M-Y2.5、基于波浪破碎作用的M-Y2.5和KPP 4种垂向混合参数化方案对模拟黄海夏季上层温度结构的影响。结果表明,M-Y2.0和基于固壁近似假定的M-Y2.5方案低估了黄海上层的湍动能,模拟的黄海夏季温度上混合层的效果与实测相比均偏浅,不能够很好地重构黄海夏季温度的垂直结构。而基于波浪破碎作用的M-Y2.5和KPP方案均可以增加海洋上层湍动能的输入量,模拟的黄海夏季温度上混合层的效果与实测较为一致。故推测黄海夏季的上层结构是受波浪混合和流场剪切等物理机制共同调节的,若通过合理的垂向混合参数化方案将这些物理机制的作用加以体现,将会较真实地模拟和重构出黄海夏季海温上层结构。 相似文献
3.
A one-dimensional mixed-layer model, including a Mellor-Yamada level 2.5 turbulence closure scheme, was implemented to investigate the dynamical and thermal structures of the ocean surface mixed layer in the northern South China Sea. The turbulent kinetic energy released through wave breaking was incorporated into the model as a source of energy at the ocean surface, and the influence of the breaking waves on the mixed layer was studied. The numerical simulations show that the simulated SST is overestimated in summer without the breaking waves. However, the cooler SST is simulated when the effect of the breaking waves is considered, the corresponding discrepancy with the observed data decreases up to 20% and the MLD calculated averagely deepens 3.8 m. Owing to the wave-enhanced turbulence mixing in the summertime, the stratification at the bottom of the mixed layer was modified and the temperature gradient spread throughout the whole thermocline compared with the concentrated distribution without wave breaking. 相似文献
4.
夏季黄海表面冷水对大气边界层及海雾的影响 总被引：3，自引：0，他引：3
海表面温度(SST)是海气界面上的1个物理量,受到海洋潮汐、海底地形等因素影响,并对海洋大气边界层有着重要的影响.夏季的黄海,由于黄海冷水团的存在和陆架锋的影响,或是潮汐混合的作用导致海水的垂直混合,使海表面温度的分布产生复杂的结构.通过对卫星观测的海表面温度数据分析,发现在夏季黄海有几个SST冷中心的存在:辽东半岛以及山东半岛的顶端、朝鲜半岛的西侧、山东半岛南侧、江苏外海和黄海南部等.本文利用一系列船舶观测资料、卫星遥感数据、再分析数据分析等,并运用数值模拟研究黄海的冷中心对其上大气的影响.在冷区之上,大气稳定度增加,抑制了近海面大气的垂直混合,使海表面风速减弱.通过对船测数据的分析,在冷区位置有海雾多发区的存在,黄海南部冷区上的海雾发生频率达到15％以上.Weather Research and Forecasting(WRF)模式的数值模拟表明,冷中心降低上空的温度,使海表面风速减弱,形成厚度达500m的逆温层,为海雾的形成创造了有利的条件.与船测数据结果所不同的是黄海南部冷中心之上的海雾发生频率可以达到30％,去掉冷区影响的试验表明冷区较冷的海表面温度最多可以使海雾的发生频率增加15％以上. 相似文献
5.
Effect of Langmuir circulation (LC) on upper ocean mixing is investigated by a two-way wave-current coupled model. Themodel is coupled of the ocean circulationmodel ROMS (regional ocean modeling system) to the surface wave model SWAN (simulating waves nearshore) via the model-coupling toolkit. The LC already certified its importance by many one-dimensional (1D) research andmechanismanalysis work. This work focuses on inducing LC’s effect in a three-dimensional (3-D) model and applying it to real field modeling. In ROMS, theMellor-Yamada turbulence closuremixing scheme is modified by including LC’s effect. The SWAN imports bathymetry, free surface and current information fromthe ROMS while exports significant wave parameters to the ROMS for Stokes wave computing every 6 s. This coupled model is applied to the South China Sea (SCS) during September 2008 cruise. The results show that LC increasing turbulence and deepening mixed layer depth (MLD) at order of O (10 m) in most of the areas, especially in the north part of SCS where most of our measurements operated. The coupled model further includes wave breaking which will bringsmore energy into water. When LC works together with wave breaking,more energy is transferred into deep layer and accelerates the MLD deepening. In the north part of the SCS, their effects aremore obvious. This is consistent with big wind event in the area of the Zhujiang River Delta. The shallow water depth as another reasonmakes themeasy to influence the oceanmixing as well. 相似文献
6.
The role of surface waves in the ocean mixed layer 总被引：7，自引：6，他引：1
Previously, most ocean circulation models have overlooked the role of the surface waves. As a result, these models have produced insufficient vertical mixing, with an under - prediction of the ,nixing layer （ML） depth and an over - prediction of the sea surface temperature （SST）, particularly during the summer season. As the ocean surface layer determines the lower boundary conditions of the atmosphere, this deficiency has severely limited the performance of the coupled ocean - atmospheric models and hence the climate studies. To overcome this shortcoming, a new parameterization for the wave effects in the ML model that will correct this systematic error of insufficient mixing. The new scheme has enabled the mixing layer to deepen, the surface excessive heating to be corrected, and an excellent agreement with observed global climatologic data. The study indicates that the surface waves are essential for ML formation, and that they are the primer drivers of the upper ocean dynamics; therefore, they are critical for climate studies. 相似文献
7.
海浪破碎对海洋上混合层中湍能量收支的影响 总被引：2，自引：1，他引：2
海浪破碎产生一向下输入的湍动能通量,在近海表处形成一湍流生成明显增加的次层,加强了海洋上混合层中的湍流垂向混合。为了研究海浪破碎对混合层中湍能量收支的影响,文中分析了海浪破碎对海洋上混合层中湍流生成的影响机制,采用垂向一维湍封闭混合模式,通过改变湍动能方程的上边界条件,引入了海浪破碎产生的湍动能通量,并分别对不同风速下海浪破碎的影响进行了数值研究,分析了混合层中湍能量收支的变化。当考虑海浪破碎影响时,近海表次层中的垂直扩散项和耗散项都有显著的增加,该次层中被耗散的湍动能占整个混合层中耗散的总的湍能量的92.0%,比无海浪破碎影响的结果增加了近1倍;由于平均流场切变减小,混合层中的湍流剪切生成减小了3.5%,形成一种存在于湍动能的耗散和垂直扩散之间的局部平衡关系。在该次层以下,局部平衡关系与壁层定律的结论一致,即湍动能的剪切生成与耗散相平衡。研究结果表明,海浪破碎在海表产生的湍动能通量影响了海洋上混合层中的各项湍能量收支间的局部平衡关系。 相似文献
8.
Effects of the surface wave-induced mixing on circulation in an isopycnal-coordinate oceanic circulation model 总被引：1，自引：1，他引：0
The influence of the nonbreaking surface wave-induced mixing under the mixed layer on the oceanic circulation was investigated using an isopycnal-coordinate oceanic circulation model. The effect of the wave-induced mixing within the mixed layer was eliminated via a bulk mixed layer model. The results show that the wave-induced mixing can penetrate through the mixed layer and into the oceanic interior. The wave-induced mixing under the mixed layer has an important effect on the distribution of temperature of the upper ocean at middle and high latitudes in summer, especially the structure of the seasonal thermocline. Moreover, the wave-induced mixing can affect the oceanic circulation, such as western boundary currents and the North Equatorial Currents through changes of sea surface height associated with the variation of the thermal structure of the upper ocean. 相似文献
9.
黄海潮生陆架锋的数值模拟研究 总被引：5，自引：2，他引：3
采用海洋三维热结构及环流模式,模拟了黄海在Ｍ２潮流混合作用下,夏季温度的分布和变化特征。从数值研究的角度,对黄海陆架水域的海洋锋现象,诸如苏北浅滩外、山东半岛东端、大连、木浦水域的锋面以及锋面沿岸一侧的表层冷水区的成因及分布进行了探讨,模拟结果再现了黄海陆架锋的潮生性质。 相似文献
10.
风生近惯性内波破碎引起的跨等密度面混合在海洋内部混合中起重要作用。然而其参数化对海洋模式的模拟影响仍有待进一步认识。本文给出的是在模块化海洋模式（MOM）中海洋表面边界层以下引入一个考虑风驱动近惯性内波破碎引起的跨等密度面混合参数化方案的研究工作。模拟结果显示，该方案有效改善MOM4模拟的上层1 000 m以上的温盐偏差，特别是在北太平洋和北大西洋的通风地区。数值试验表明，风生近惯性内波破碎有可能是维持海洋通风过程的重要机制之一，它使得海洋通风区的位温变冷，盐度变淡，整层等位密面加深。维持的通风过程使得北太平洋副极地大涡的影响延伸到副热带大涡。从而模拟的北太平洋中层水源头及其副热带大涡东侧的温盐更接近观测实际。同时，模拟的北大西洋经圈翻转环流强度也更为合理。 相似文献
11.
《Ocean Modelling》2004,6(1):83-100
A series of vertical mixing schemes implemented in a circumpolar coupled ice–ocean model of the BRIOS family is validated against observations of hydrography and sea ice coverage in the Weddell Sea. Assessed parameterizations include the Richardson number-dependent Pacanowski–Philander scheme, the Mellor–Yamada turbulent closure scheme, the K-profile parameterization, a bulk mixed layer model and the ocean penetrative plume scheme (OPPS). Combinations of the Pacanowski–Philander parameterization or the OPPS with a simple diagnostic model depending on the Monin–Obukhov length yield particularly good results. In contrast, experiments using a constant diffusivity and the traditional convective adjustment cannot reproduce the observations. An underestimation of wind-driven mixing in summer leads to an accumulation of salt in the winter water layer, inducing deep convection in the central Weddell Sea and a homogenization of the water column. Large upward heat fluxes in these simulations lead to the formation of unrealistic, large polynyas in the central Weddell Sea after only a few years of integration. Furthermore, spurious open-ocean convection affects the basin-scale circulation and leads to a significant overestimation of meridional overturning rates. We conclude that an adequate parameterization of both wind-induced mixing and buoyancy-driven convection is crucial for realistic simulations of processes in seasonally ice-covered seas. 相似文献
12.
The role of wave breaking (WB) in the ocean dynamics in the Bohai Sea, China under typhoon condition is systematically investigated utilizing a coupled wave-current model. The influences of WB on ocean dynamics and processes (mixing coefficient, temperature, mixed layer depth, and current) during the entire typhoon period (including the pre-typhoon, during-typhoon and after-typhoon stages) are comprehensively detected and discussed. Experimental results show that WB greatly enhances the turbulent mixing at about top 10 m depth under typhoon condition, the increase can be up to 10 times that of the normal weather. At the same time, WB generally strengthens the sea surface cooling by ~1.2°C at the during-typhoon stage, about 3 times that in normal weather. The mixed layer depth, is rapidly increased by ~1.6–3.6 m during typhoon due to WB, particularly, the deepening is stronger in the region from 120.5°E to 121.0°E on account of close to the typhoon eye. In addition, WB renders the current speed more uniformly within the entire depth in the Bohai Sea, the change in speed is ~0.2 m/s, whereas the alternation in current vector is generally opposite to the wind direction except for the typhoon eye region, reflecting that WB has an inhibitory effect on the typhoon-forced current change. The effects of WB on vertical mixing coefficient response to the typhoon rapidly, while the impacts of WB on temperature, and mixed layer depth present hysteretic responses to typhoon. Finally, the mechanisms and distribution characteristics of WB-induced mixing and tidal mixing are compared under typhoon condition. 相似文献
13.
Assimilation of sea surface temperature in the Northwest Pacific Ocean and its marginal seas using the ensemble Kalman filter 总被引：2，自引：0，他引：2
Gwang-Ho Seo Byoung-Ju Choi Yang-Ki Cho Young Ho Kim Sangil Kim 《Ocean Science Journal》2010,45(4):225-242
Satellite-borne sea surface temperature (SST) data were assimilated with the ensemble Kalman filter (EnKF) in a Northwest Pacific Ocean circulation model to examine the effect of data assimilation. The model domain included the northwestern part of the Pacific Ocean and its marginal seas, such as the Yellow Sea and East/Japan Sea. The performance of the data assimilation was evaluated by comparing the simulated ocean state with that observed. Spatially averaged root-mean-squared errors in the SST and sea surface height (SSH) decreased by 0.44 °C and 4 cm, respectively, by the assimilation. The results of the numerical experiments substantiated the effectiveness of the SST assimilation via the EnKF for all marginal seas, as well as the Kuroshio region. The benefit of the data assimilation depended on the characteristics of each marginal sea. The variation of the SST in the East/Japan Sea and the Kuroshio extension (KE) region were improved 34% and those in the Yellow Sea 12.5%. The variation of the SSH was improved approximately 36% in the KE region. This large improvement was achieved in the deep-water regions because assimilation of SST data corrected the separation point of the western boundary currents, such as the Kuroshio and the East Korea Warm Current, and the associated horizontal surface currents. The SST assimilation via the EnKF also improved the subsurface temperature profiles. The effectiveness of SST assimilation was seasonally dependent, with the improvement being relatively larger in winter than in summer, which was related to the seasonal variation of the vertical mixing and stratification in the ocean surface layer. 相似文献
14.
潮致混合对海洋环流的调整起着重要作用。陆架环流的数值模拟中如果不考虑潮汐作用，往往不能得到与观测相符的垂向温盐结构。本文基于调和分析方法，建立了一套潮致混合参数化方案。该方案通过对垂向混合系数进行调和分析，从而得到随时间变化的潮致混合系数。将该方案用于黄海冷水团数值模拟的结果显示，其能够得到与在数值模式开边界直接加入潮汐强迫相当的冷水团温盐结构。和直接引入潮汐强迫相比，这一潮致混合参数化方案的优势在于，它能够大大节省数值模拟计算机时，因此有望显著提高大规模高分辨率的海洋环流及气候模式的模拟能力和计算效率。 相似文献
15.
在大洋环流模型中对应于惯性内波破碎的垂直混合的一个参数化方案 总被引：1，自引：0，他引：1
Based on the theoretical spectral model of inertial internal wave breaking(fine structure) proposed previously, in which the effects of the horizontal Coriolis frequency component f-tilde on a potential isopycnal are taken into account, a parameterization scheme of vertical mixing in the stably stratified interior below the surface mixed layer in the ocean general circulation model(OGCM) is put forward preliminarily in this paper. Besides turbulence, the impact of sub-mesoscale oceanic processes(including inertial internal wave breaking product) on oceanic interior mixing is emphasized. We suggest that adding the inertial internal wave breaking mixing scheme(F-scheme for short) put forward in this paper to the turbulence mixing scheme of Canuto et al.( T-scheme for short) in the OGCM, except the region from 15°S to 15°N. The numerical results of F-scheme by using WOA09 data and an OGCM(LICOM, LASG/IAP climate system ocean model) over the global ocean are given. A notable improvement in the simulation of salinity and temperature over the global ocean is attained by using T-scheme adding F-scheme, especially in the mid- and high-latitude regions in the simulation of the intermediate water and deep water. We conjecture that the inertial internal wave breaking mixing and inertial forcing of wind might be one of important mechanisms maintaining the ventilation process. The modeling strength of the Atlantic meridional overturning circulation(AMOC) by using T-scheme adding F-scheme may be more reasonable than that by using T-scheme alone, though the physical processes need to be further studied, and the overflow parameterization needs to be incorporated. A shortcoming in F-scheme is that in this paper the error of simulated salinity and temperature by using T-scheme adding F-scheme is larger than that by using T-scheme alone in the subsurface layer. 相似文献
16.
湍流扩散过程导致的硝酸盐垂向输运对海水表层的浮游植物生长和初级生产力的大小有着重要影响。本文基于2018年夏季黄、东海水文环境、硝酸盐浓度和湍动能耗散率的同步、原位数据，分析了海域温度、盐度和硝酸盐的空间分布特征，结果表明营养盐含量丰富的黄海冷水团、长江冲淡水、东海北部底层混合水与黑潮次表层水是影响研究海域硝酸盐分布的主要水团。利用垂向湍扩散硝酸盐通量公式，计算了三个选定断面上的硝酸盐垂向扩散通量，其高值区与湍流扩散系数的高值区的位置基本一致。针对存在明显硝酸盐跃层的站位，计算得到跨硝酸盐跃层的垂向通量FND的范围在-9.78—36.60mmol/（m2·d）之间，在黄海冷水团区，夏季温跃层限制了该区营养盐向近表层的湍流垂向扩散；东海北部底层混合水区，湍流垂向扩散向上层补充了大量硝酸盐，促进了跃层之上浮游植物的生长；黑潮次表层水影响海区，夏季中层水体混合较弱，跨跃层的垂向通量也普遍偏低。开展硝酸盐垂向扩散通量的计算与分析，对进一步明确营养盐的输运机制有着重要研究意义。 相似文献
17.
基于海浪模式WAVEWATCH Ⅲ模拟北太平洋海浪要素,结合NDBC浮标资料进行验证,发现模拟出的有效波高与浮标测量值具有很好的一致性。基于改进型白冠覆盖率耗散模型,利用海浪模式模拟出的有效波高、有效波周期和摩擦速度等海浪要素计算出单位面积水柱内因海浪破碎产生的湍动能通量。通过改变环流模式sbPOM湍动能方程的上边界条件,引入海浪破碎产生的湍动能通量,并探究海浪破碎对北太平洋海表面温度模拟的影响。研究表明,由于海浪破碎的引入,环流模式sbPOM对北太平洋海表面温度模拟的准确程度得到提升,这为大气模式提供一个准确的北太平洋下边界条件具有重要意义。 相似文献
18.
Intercomparison of three South China Sea circulation models 总被引：1，自引：1，他引：1
1IntroductionTheSouthChinaSeaisthelargesttropicalmarginaldeepsealocatingbetweenthewesternPacificOceanandtheeasternIndianOcean.AsapartofAsia-Australiamaritimecontinent,monsoonisaprimaryfactorforcingtheSouthChinaSeaCurrent(SCSC)variation.Drivenbynortheasterlymonsooninwinterandsouth-westerlymonsooninsummer,respectively,theSCSCbehavesacyclonicgyreandananticy-clonicgyre,correspondingly(Wyrtki,1961;Xuetal.,1982).Owingtotheshortageandexpen-sivenessofdirectobservationsintheSCS,fur-therunder… 相似文献
19.
海浪搅拌混合对北太平洋海表面温度模拟的影响 总被引：1，自引：1，他引：0
利用NCEP再分析风场驱动WAVEWATCH III海浪模式对北太平洋海域的海浪过程进行模拟,利用浮标观测资料对模拟出的海浪要素有效波高进行验证,发现他们之间具有很好的一致性。基于模式输出的有效波高等波浪要素,利用特征波参数化理论,在海洋环流模式中引入海浪搅拌混合作用,分析其对北太平洋海表面温度模拟的影响,初步数值模拟结果表明,sbPOM模式在考虑海浪搅拌混合作用以后,模拟精度进一步提升,这对提供一个准确的大气模式下边界条件具有重要作用。 相似文献
20.
根据北黄海夏季断面1976~2015年历年8月监测资料,采用时空分析等方法,研究了北黄海夏季断面溶解氧含量和表观耗氧量年际变化时空模态.溶解氧含量与表观耗氧量年际变化分别有3种主要时空模态,第一、二模态是近底层水体低氧、贫氧年际变化的主要影响分量,第三模态是混合层水体高氧、富氧年际变化主要影响分量.生物活性组分(BAC)耗-生氧与海洋环流输送增减氧过程是夏季溶解氧含量与表观耗氧量年际变化主要影响因素,温跃层强度年际变化不是主要影响因素.2001年后,表层月海气氧通量年际变化由氧汇分布为主转变为氧源分布,表层溶解氧含量增大以及生物活性组分生氧作用增强年际变化是这种转变的原因.北黄海夏季断面年平均溶解氧含量、表观耗氧量空间分布相似性较低,夏季断面年平均温度、盐度以及沉积物需氧、风生环流是年平均溶解氧含量、表观耗氧量分布的主要影响因素.生物活性组分耗-生氧过程是断面各层月平均溶解氧含量、表观耗氧量年际变化主要影响因素,温度变化是次要因素.由于断面水体低氧幅度与贫氧面积显著线性增大,与30多年前比较,黄海溶解氧含量、表观耗氧量场季节变化空间分布与时间形态已经发生改变. 相似文献