共查询到20条相似文献，搜索用时 15 毫秒
1.
The influence of both spatial and temporal temperature inhomogeneities of the underlying surface on the temperature field in an unstably stratified atmospheric surface layer is considered. The methods of correlation and spectral analyses are proposed to estimate statistical characteristics of surface-air temperature fluctuations caused by both turbulent mixing and inhomogeneities in the temperature of the underlying surface. Analysis of experimental data obtained from measurements in the atmospheric surface layer yields estimates for the contribution made by the time-dependent thermal properties of the underlying surface to the total variance of air-temperature fluctuations. It is shown that the additional air-temperature fluctuations generated by surface-temperature inhomogeneities and unrelated to shear flow may reach 70% and 30% of the total variance of measured fluctuations under variable cloudiness and clear skies, respectively. For the height z = 2 m within the wave-number range 2 × 10?3 rad m?1 < k < 0.1 rad m?1, the contribution made by a spatial surface-temperature inhomogeneity to the variance of air-temperature fluctuations does not exceed 10% of the total variance. Correlation and spectral analyses of experimental data make it possible to isolate the spectra of properly turbulent fluctuations from the measured fluctuations and thus to obtain more accurate values of the universal function of similarity theory for temperature in the range of small wave numbers beyond the inertial range. 相似文献
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2015年4月7-30日,在浙江省舟山近海海域开展了“嵊山-朱家尖”小型阵列变频高频地波雷达系统的海上比测试验,通过雷达观测数据与定点ADCP海流资料的比对检验了地波雷达表层流探测性能。径向流比对结果显示,测点与雷达法向夹角越小,距离雷达距离越近,径向流比测结果越好,雷达探测的结果越可靠。嵊山站径向流与ADCP观测结果的各站总体平均误差为7.98 cm/s,平均均方根误差为15.34 cm/s,平均相关系数为0.89,朱家尖站径向流与ADCP观测结果的各站总体平均误差为6.24 cm/s,平均均方根误差为12.36 cm/s,平均相关系数为0.81。根据矢量流比对结果显示,矢量流速与ADCP观测结果的各站总体平均误差为4.82 cm/s,平均均方根误差为15.03 cm/s,平均相关系数为0.44。设置在嵊山、朱家尖两个雷达站双站探测的核心区域（两个雷达站连线的中垂线上,并且与两个雷达站构成一个近似直角三角形）的站点比测结果更加理想,当流速大于0.25 m/s时,对于核心区域平均后的流向均方根误差为24.9°。 相似文献
3.
Kern E. Kenyon 《Journal of Oceanography》1991,47(2):45-48
The cyclostrophic balance (pressure forcevs. force centrifugal force) is shown to be satisfied for all fluid particles in surface gravity waves with sinusoidal form and
circular particle orbits. Consequences of the cyclostrophic balance are 1) that the normal dispersion relation for deep water
hold and 2) that the orbital radius decrease with increasing depth at the usual exponential rate, from which it follows that
the wave pressure and particle speed also decrease with depth exponentially. In addition, the cyclostrophic and hydrostatic
balances together predict wave breaking at the crests for amplitudes exceeding one divided by the wave number. In contrast
to the traditional perturbation method, based on irrotational flow, the cyclostrophic method does not demand that the amplitude
be much less than a wave length and does not require an infinite wave train. 相似文献
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连续台风对海表温度和海表高度的影响 总被引：1，自引：0，他引：1
利用多卫星观测资料,分析了2008年9月3个连续台风前后的海表温度(SST)和海表高度距平(SSHA)的时空变化特征,并探讨了影响其变化的主要因子。结果表明:(1)3个台风引起了强烈的上升流(1×10-5~150×10-5 m/s),海表显著降温(1~6 ℃),海表高度也有不同程度降低(10~50 cm);(2)台风引起的SST最大降温中心与SSHA负值或中尺度冷涡的区域中心十分吻合,同时台风使得先前存在的海洋中尺度冷涡得到加强;(3)同一区域台风对SST影响程度大小受台风的强度、移动速度以及台风对海面强迫时间等因素控制;(4)在原先SSHA为正值的海域,3个台风连续强迫下使得局地洋面形成一个SSHA为负值的中尺度涡,这与单一"打转"台风强迫海洋生成中尺度涡的现象不同。因此,对于西北太平洋海域而言,频发的台风在中尺度涡生消演变过程中的影响应不容忽视。 相似文献
6.
《Ocean Modelling》2011,39(3-4):267-279
Near-surface enhancement of turbulent mixing and vertical mixing coefficient for temperature owing to the effect of surface wave breaking is investigated using a two-dimensional (2-D) ocean circulation model with a tidal boundary condition in an idealized shelf sea. On the basis of the 2-D simulation, the effect of surface wave breaking on surface boundary layer deepening in the Yellow Sea in summer is studied utilizing a 3-D ocean circulation model. A well-mixed temperature surface layer in the Yellow Sea can be successfully reconstructed when the effect of surface wave breaking is considered. The diagnostic analysis of the turbulent kinetic energy equation shows that turbulent mixing is enhanced greatly in the Yellow Sea in summer by surface wave breaking. In addition, the diagnostic analysis of momentum budget and temperature budget also show that surface wave breaking has an evident contribution to the turbulent mixing in the surface boundary layer. We therefore conclude that surface wave breaking is an important factor in determining the depth of the surface boundary layer of temperature in the Yellow Sea in summer. 相似文献
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An analytical model including the boundary-layer effect is developed to find the steady drift induced by the non-linear effect of the surface-wave motion. The analytical result is compared with the experimental results obtained from a wave tank. Results show a qualitative agreement. A semi-empirical formula which predicts drift velocity of a contaminant layer on the free surface is introduced and its validity is investigated. 相似文献
9.
Aquatic surface microlayer contamination in chesapeake bay 总被引：1，自引：0，他引：1
John T. Hardy Eric A. Crecelius Liam D. Antrim Steven L. Kiesser Virginia L. Broadhurst 《Marine Chemistry》1990,28(4)
The aquatic surface microlayer (SMIC), 50 μm thick, serves as a concentration point for metal and organic contaminants that have low water solubility or are associated with floatable particles. Also, the eggs and larvae of many fish and shellfish species float on, or come in contact with, the water surface throughout their early development. The objectives of this study were (1) to determine the present degree of aquatic surface microlayer pollution at selected sites in Chesapeake Bay, and (2) to provide a preliminary evaluation of sources contributing to any observed contamination.Twelve stations located in urban bays, major rivers, and the north central bay were sampled three times, each at 5-day intervals during May 1986. Samples of 1.4–4.1 each were collected from the upper 30–60-μm water surface (surface microlayer, SMIC) using a Teflon-coated rotating drum microlayer sampler. One sample of subsurface water was collected in the central bay.At all stations, concentrations of metals, alkanes, and aromatic hydrocarbons in the SMIC were high compared with one bulk-water sample and with typical concentrations in water of Chesapeake Bay and elsewhere. SMIC contamination varied greatly among the three sampling times, but high mean contaminant levels (total polycyclic aromatic hydrocarbons, 1.9–6.2 μg 1−1; Pb, 4.9–24 μg 1−1; Cu, 4–16 μg 1−1; and Zn, 34–59 μg 1−1) were found at the upper Potomac and northern bay sites. Three separate areas were identified on the basis of relative concentrations of different aromatic hydrocarbons in SMIC samples - the northern bay, the Potomac River, and the cleaner southern and eastern portions of the sampling area.Suspected sources of surface contamination include gasoline and diesel fuel combustion, coal combustion, and petroleum product releases. Concentrations of metals and hydrocarbons, at approximately half the stations sampled, are sufficient to pose a threat to the reproductive stages of some fish and shellfish. Sampling and analysis of the surface microlayer provides a sensitive tool for source identification and monitoring of potentially harmful aquatic pollution. 相似文献
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采用阳极溶出伏安法(ASV)对1999年10月采自浙江省三门湾健跳港表层海水中溶解态铅的形态进行了分析,结果表明:海水中游离态铅的浓度为2.2 nmol/dm3,有机配位态则可分为两类,即PbL1和PbL2;两类有机配位体条件稳定常数的对数(logKpcobnLd1,pb2 和logKpcobnLd2,pb2 )分别为8.4和9.1;两类有机配位体浓度(L1和L2)分别为37.4 nmol/dm3和52.7 nmol/dm3,将上述结果与以往三门湾海区研究中海洋生物急性毒性试验结果和不同介质中铅含量进行对比可知,浙江三门湾健跳港海区表层海水中溶解态铅浓度对海洋生物是安全的,但个别底栖生物物种中较高的铅含量已影响到人类的食用安全。 相似文献
11.
采用1982-2012年NOAA最优插值海表温度(第二版)数据资料和NCEP/NCAR再分析海表气温数据资料,利用均方差分析法,分析海表温度和海表气温的年际变化特征。将31年数据按照El Nin軌o/La Nin軌a事件分为a,b,c 3组,利用超前/滞后相关性分析法,将中低纬度海域海表温度异常(SSTA)与海表气温异常(SATA)做超前/滞后相关分析,得到每个格点SSTA与SATA之间相关性最显著的时间,从而确定SSTA与SATA之间的超前/滞后相关关系。研究结果表明:中纬度海域以SATA超前SSTA为主,SATA滞后SSTA主要分布在20°S-20°N的热带海域。SATA与SSTA超前/滞后天数统计结果均呈现双峰型分布,SATA超前峰值出现在10 d左右,SATA滞后峰值出现-7 d左右。El Nin軌o/La Nin軌a事件的出现,对海气超前/滞后相关关系具有一定影响。 相似文献
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于2011年10月对大亚湾坝光海域表层海水和沉积物的酸可挥发性硫化物(AVS)及相关环境因子进行了调查研究.结果显示,20个测站表层海水的AVS含量在0.039 ～0.129 mg/dm3之间,平均0.070 mg/dm3,区域分布规律不显著;12个测站的表层沉积物中均检测出AVS,其含量(干重)范围是12.8 ～ 867.7 mg/kg,平均为272.4 mg/kg,整体呈近岸较高、离岸较低的分布规律.相关性分析显示,表层水体pH值、CCOD和CDo等环境因子与CAVS相关系数的绝对值均较小,相关性特征不明显;表层沉积物中的CAVS与Eh之间的相关系数为-0.957,呈高度相关性,符合挥发性硫化物含量较高的沉积物处于较强还原状态的普遍规律;大亚湾表层沉积物中的CAVS与pH值、CTOC的相关系数分别为-0.065和0.219,相关性不显著.单因子污染指数评价结果表明,大亚湾坝光海域表层海水硫化物含量已超过所在自然保护区(一类标准)和养殖区(二类标准)所要求的水质标准,局部水体已受到污染;表层沉积物中硫化物含量符合国家一类标准,环境质量良好. 相似文献
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Sirilath J. DeSilva Ronald B. Guenther Robert T. Hudspeth 《Applied Ocean Research》1996,18(6):293-302
Oscillatory, two dimensional free-surface, irrotational flows of an incompressible fluid are treated numerically. Rather than basing the treatment on perturbation expansions, the unknown fluid domain bounded by a free surface is mapped onto a rectangular domain. This has the effect of exchanging a boundary value problem for a linear, constant coefficient Laplace equation having nonlinear boundary conditions into a nonlinear elliptic equation specified on the known rectangular domain. In the known transformed domain, compatibility conditions at the corners are derived, the boundary value problem is solved and the results are transformed back to the original domain. 相似文献
14.
Adiabatic density surface,neutral density surface,potential density surface,and mixing path* 
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下载免费PDF全文 HUANG Rui-xin 《热带海洋学报》2014,33(4):1-19
In this paper,adiabatic density surface,neutral density surface and potential density surface are compared.The adiabatic density surface is defined as the surface on which a water parcel can move adiabatically,without changing its potential temperature and salinity.For a water parcel taken at a given station and pressure level,the corresponding adiabatic density surface can be determined through simple calculations.This family of surface is neutrally buoyant in the world ocean,and different from other surfaces that are not truly neutrally buoyant.In order to explore mixing path in the ocean,a mixing ratio m is introduced,which is defined as the portion of potential temperature and salinity of a water parcel that has exchanged with the environment during a segment of migration in the ocean.Two extreme situations of mixing path in the ocean are m=0(no mixing),which is represented by the adiabatic density curve,and m=1,where the original information is completely lost through mixing.The latter is represented by the neutral density curve.The reality lies in between,namely,0m1.In the turbulent ocean,there are potentially infinite mixing paths,some of which may be identified by using different tracers(or their combinations)and different mixing criteria.Searching for mixing paths in the real ocean presents a great challenge for further research. 相似文献
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海面阻力系数的流体力学研究 总被引：1，自引：0，他引：1
利用相似理论的方法 ,把解决湍流问题的尼古拉兹曲线引入到风应力的计算中。阐明了决定海面阻力系数的关键因素是海浪的平均波高及摩擦层厚度 ,并推出了它们之间的关系式。 相似文献
16.
深圳湾表层沉积物中重金属的分布 总被引：7，自引：0，他引：7
本文在1986年4月至1989年1月间深圳湾12次环境调查资料的基础上,报道了6个调查站的表层沉积物中6种重金属元素(Cu、Pb、Zn、Cd、Cr、N(?))的含量及其时空分布特征,以及表层沉积物中重金属的含量与环境因子的相关分析结果,并且对该湾表层沉积物中重金属的污染程度作出了评价,为今后深圳湾环境质量综合评价提供了背景资料。 相似文献
17.
L. F. Chernogor 《Izvestiya Atmospheric and Oceanic Physics》2008,44(4):432-447
The results of single-type optical observations, analysis, and comparison of dynamic characteristics of the effects in the surface atmosphere that accompanied four partial solar eclipses (August 11, 1999; May 31, 2003; October 3, 2005; March 29, 2006) near the city of Kharkiv (Ukraine) are presented. The effects observed in the morning, near-noon, and afternoon hours differed markedly. During the solar eclipses, the temperature of the surface atmosphere decreased by 1.3–7.3°. It was detected that, when the maximum value of the occultation function changed from 0.24 to 0.73, the standard deviation of solar-limb displacement σ S decreased by 0.14″ and 0.68″, respectively. The time of convection development was found to be 15–16 min. The parameters of dynamic processes in the surface atmosphere have been calculated and the parameters of mechanical and thermal turbulence have been estimated from the results of measurements of the statistical characteristics of the level of solar-limb tremor with invocation of theoretical relations. The solar eclipses were accompanied by quasi-periodic processes in the atmosphere, which were most likely associated with the generation and propagation of internal gravity waves. 相似文献
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调查及综合研究了台湾海峡表层沉积物中底栖有孔虫的分布特征,调查海区根据优势种类组成可以划分出１０个底栖有孔虫动物群,其经峡东侧所划分的６个义栖有孔虫生物相有机相连。动物群的分布与现代海洋环境有密切关系,从而对台湾海峡的古地理环境研究提供了依据。 相似文献
19.
Iodine in sea water of the Pacific was determined with special interest in the relation between iodide and iodate in the surface water of the ocean. The result was discussed with reference to the mechanism of iodide formation proposed byTsunogai andSase. The concentration of iodide varies widely from the lower value than the detection limit to 0.21g at./l, while the concentration of total iodine is nearly constant and the mean value is 0.41g at./l. The vertical profile of iodide often shows the maximum in the surface layer. In the surface layer, the concentration of iodide is higher in warm water (0,10g at./l on the average) than that in cold water of lower temperature than 20° C (0.03g at/l). The highest concentration of iodide among the warm waters is found in the surface water of the equatorial area (0.13g at./l) where the biological productivity is also high. Iodide is generally more enriched in the water having higher biological activity even in the cold water. These results are considered to be compatible with the mechanism of iodide formation proposed. 相似文献
20.
An analysis of two-dimensional horizontal plane shear dispersion in steady, periodic, almost-periodic and randomly forced skewed free surface flow is presented. A two-time scale perturbation analysis of the advection-diffusion equation is used to derive the two-dimensional advection-dispersion equation and the horizontal dispersion coefficient tensor. For combinations of steady, periodic and almost-periodic flow, the time dependent dispersion coefficient tensor contains steady terms and periodic terms at frequencies associated with the forcing frequencies and their sums and differences. For combinations of steady, periodic, almost-periodic and stationary random forcings, the expected value dispersion coefficient tensor contains terms associated with the steady forcings and terms associated with the unsteady forcings represented by the spectral density functions of the unsteady forcings. Estimates of the magnitude of the expected value dispersion coefficient tensor are presented for representative estuarine and continental shelf conditions. 相似文献