共查询到20条相似文献，搜索用时 46 毫秒
1.
Using available wind wave spectra data, we consider the applicability conditions of the tangent plane (Kirchhoff) method and the small perturbations and diffusion (Rayleigh) method to construct microwave diagrams of sea surface scattering (quasi-mirror forward scattering). We take into account the peculiarities of Earth sensing from orbit, the closeness of viewing of a mirror point to the Brewster angle, and the possibility of simultaneous formation of wide-capture radar images for the coaxial and collinear polarization components of a reflected signal. It is concluded that, taking into account the approximations made, it is possible to creat panorama small- and mesoscale images of the field of wind wave slopes for a coverage area on the order of 2000 km. Then, based on earlier engineering design studies, we present three possible modifications of “tandem” space radar designed to efficiently solve certain oceanological and applied problems. 相似文献
2.
We consider the influence of the sea surface state on the backscattered radar cross section and the accuracy of the wind speed retrieval from the scatterometer data. We used a joint set of radars and buoys to determine the type of sea waves. Three types of sea waves were distinguished: developing wind waves, fully developed wind waves, and mixed sea. It is shown that the retrieval error of the near surface wind speed using a one-parameter algorithm is minimal in the case of fully developed wind waves. We compared these data with the results of radio-altimeter data analysis and showed that in both cases underestimation of the retrieval wind speed exists for developing wind waves and overestimation occurs for mixed sea. A variety of swell parameters (length of the dominating wave, swell height, swell age) significantly influence the backscattered radar cross section, leading to a growth in the mean square error of the retrieved wind speed during vertical sounding (radio-altimeter data), and only slightly influence the mean square error of the scatterometer data (medium incidence angles). It is necessary to include the information about the parameters of sea waves in the algorithms and take into account the regional wave properties to increase the accuracy of wind speed retrieval. 相似文献
3.
I. N. Ivanova O. N. Mel’nikova T. A. Nivina K. V. Pokazeev 《Izvestiya Atmospheric and Oceanic Physics》2006,42(5):646-652
The air-flow velocity field near the water surface is studied in the zone of wind-wave intensification. Caused by a periodic separation of eddies, a nonzero time-averaged value of the wind velocity in the near-water streamline is detected at the leading slope of the wave. The distribution of pressure along the wave with allowance for the vertical velocity shear and disturbances produced by eddies and a periodic deceleration of the viscous layer was calculated with the aid of the Cauchy-Lagrange integral. This procedure made it possible to calculate the growth rate of the wave amplitude, whose value was found to be close to its experimental value at the initial stage of acceleration. 相似文献
4.
台风风剖面信息是直观反映与台风中心不同距离的各点与平均风速关系的曲线,它是确定各级台风风圈范围的重要基础。本文利用HY-2A微波散射计海面风场资料,结合Holland风场模型提出了一种新的台风风剖面信息提取方法,并选取2012–2017年期间16期典型台风进行应用。结果表明:34 kt与50 kt风圈半径的平均均方根误差为37.6 km与18.3 km,该方法具有较好的适用性和精度。本研究对于描述台风结构特征及潜在的破坏力和台风可能的影响范围具有一定的现实意义。 相似文献
5.
We present a model of the processes of development in the ecosystem of the coastal zone of the sea constructed by the method
of adaptive balance of causes (ABC-method). The model contains nine variables (phyto- and zooplankton, fish larvae, fishes, oxygen, carbon dioxide, salinity,
biogenic elements, and detritus) affected by the solar radiation, surface wind, sea temperature, and river discharge. The
equations of the model contain control agents governing the dependences of the elements of the food chain on the vitally important
resources and environmental conditions. The scenarios of the processes of development are constructed for the simulated annual
courses of external actions. The possibility of management of fish resources by regulating the flows of biogenic elements
and detritus with river discharge is discussed. A mechanism of management based on the monitoring of the concentration of
dissolved oxygen in seawater is proposed. The numerical experiments show that the ABC-model of the processes of development in the ecosystem of the coastal zone of the sea makes it possible to simulate the scenarios
of regulation of the flows of biogenic elements and detritus into the sea with an aim of preservation of of fish resources.
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 36–49, January–February, 2009. 相似文献
6.
I. E. Timchenko A. A. Primalenny V. D. Yarin E. F. Vasechkina E. M. Igumnova 《Physical Oceanography》2001,11(4):367-378
We use many-year archival observations of hydrologic and hydrobiologic state of the Sea of Azov for the identification of
the structure of a model of its ecosystem. The ecosystem model, supplemented with expert estimates of bioresource consumption
(fish reserve), contamination level, and possible ecologic fines for violation of the sea natural state, is formalized by
the method of system dynamics. Hereat, the major part of influence functions is found in terms of observational data with
application of self-organization algorithms. We also present the results of simulated experiments with the model of the ecosystem,
which enable us to analyse scenarios of its behaviour under the influence of various external factors (wind, river discharge,
water exchange with the Black Sea, etc.).
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
7.
We show that the parameters of primary radar images obtained from theSich-1 satellite depend on the mode of survey and that the time dependence of the coefficient of correction of amplification in
the channel of formation of radar signals is nonlinear. We propose to process radar images of the sea surface by using the
so-called Bragg normalization of signals, which enables one to get a physically correct dependence of specific effective scattering
surface on the elevation angle. We also consider a procedure of determination of the dependence of specific effective scattering
surface of the sea on the wind velocity on the basis of the data accumulated by the side-looking radar of theSich-1 satellite.
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
8.
Yu. I. Troitskaya D. A. Sergeev O. S. Ermakova G. N. Balandina 《Izvestiya Atmospheric and Oceanic Physics》2010,46(1):109-120
In this paper, the results of a laboratory experiment on investigating the wind-velocity field over a water surface using
the PIV method are described. The use of a rapid CCD-camera made it possible to perform a detailed study of the eddy structure
of airflow. We have measured the velocity fields over a flat plate by wind waves and waves induced by a wave generator. The
model of a turbulent boundary layer over a rough surface was directly verified. It has been shown that the wind-velocity profiles
over waves obtained by averaging the instantaneous fields over the ensemble of samples and horizontal coordinate are satisfactorily
consistent with the profiles calculated within the frameworks of the model of wind flow over rough water surface. 相似文献
9.
E. M. Volodin S. V. Kostrykin A. G. Ryaboshapko 《Izvestiya Atmospheric and Oceanic Physics》2011,47(4):430-438
An atmosphere-ocean general circulation model including the atmospheric chemistry and carbon cycle was used to perform numerical experiments to simulate the consequences of geoengineering. Out of the five emission scenarios considered here, the scenario where the injection of sulfur compounds occurs near the equator at an altitude between 22 and 24 km can be considered the most efficient in the sense of a maximum decrease in globally averaged surface temperature. We consider the equilibrium distribution of the sulfate aerosol and changes in temperature at the Earth’s surface and at different altitudes, in precipitation, in ozone concentration, and in primary plant productivity caused by geoengineering. 相似文献
10.
渤海悬浮颗粒物三维输运模式的研究 Ⅱ.模拟结果 总被引：6，自引：4，他引：6
利用本文Ⅰ给出的悬浮物输运的三维动力数值模式，在渤海中进行了两种情形下的模拟。首先模拟了黄河排出的细颗粒物在渤海中的运动，结果表明，这些颗粒物大部分将滞留在渤海内，而且其分布与气象条件有密切关系。另外对大风情况下悬浮物的输运进行了模拟，结果显示，大风到来时海水中的悬浮物浓度急剧上升，海底侵蚀增强，而风停止时，悬浮物浓度经过一段时间延迟后，会恢复到正常状态。这与实际观测的趋势是一致的，表明用本模式研究悬浮物的输运是可行的。 相似文献
11.
This paper introduces a new method to estimate the long-term regional hurricane wind and storm surge hazard. The output is a relatively small set of hurricane scenarios that together represent the regional hazard. For each scenario, the method produces a hazard-consistent annual occurrence probability, and wind speeds and surge levels throughout the study area. These scenarios can be used for subsequent evacuation or loss estimation modeling. This optimization-based probabilistic scenario (OPS) method involves first simulating tens of thousands of candidate hurricane scenarios with wind speeds and approximate surge depths. A mixed-integer linear optimization is then used to select a subset of scenarios and assign hazard-consistent annual occurrence probabilities to each. Finally, a surge model is used to estimate accurate surge depths for the reduced set of events. The method considers the correlation between winds and surge depths and the spatial correlations of each; it is computationally efficient; and it makes explicit the tradeoff between the number of scenarios selected and the errors introduced by using a reduced set of events. A case study for Eastern North Carolina is presented in which a final set of 97 hurricanes provides unbiased results with errors small enough for many practical uses. 相似文献
12.
G. Michelacci 《Ocean Engineering》1983,10(3):171-180
A stochastic model is reported for the rolling motion due to wind gusts having a non-uniform Poisson distribution and a constant amplitude.This paper is an improvement on a previous one where the external exciting term due to wind was au niform Poisson process.The statistics of the rolling motion amplitude process which is non-stationary are obtained and used for deriving a majorizing function for the probability of capsizing.The resulting inequality is used for a small cargo ship. 相似文献
13.
C.G. Simionato A. Berasategui V.L. Meccia M. Acha H. Mianzan 《Estuarine, Coastal and Shelf Science》2008
The Río de la Plata Estuary presents a strong bottom salinity front located over a submerged shoal. Apparently favored by retention processes, it is a spawning ground for several coastal fishes. This estuary is very shallow and essentially wind driven and, moreover, in time scales relevant to biota, estuarine circulation is wind dominated and highly variable. Two intriguing questions are, therefore, how this system can favor retention and what the involved mechanisms are. This paper qualitatively explores mechanisms involved in the estuary where retention is favored applying numerical simulations in which neutral particles – simulating fish eggs and early larvae – are released along the bottom frontal zone and tracked for different wind conditions. Results suggest that retentive features can be a consequence of estuarine response to natural wind variability acting over bathymetric features. For winds from most directions, particles either remain trapped near their launching position or move northeastward to southwestward along the shoal. As alternation of winds that favor along-shoal motion is the dominant feature of wind variability in the region, a retentive scenario results from prevailing wind variability. Additionally, winds that tend to export particles with a poor chance of being restored to the front are neither frequent nor persistent. Results show, therefore, that physical forcing alone might generate a retentive scenario at the inner part of this estuary. The physical retention mechanism is more effective for bottom than for surface launched particles. Wind statistics indicate that the proposed mechanism has different implications for retention along the seasons. Spring is the most favorable season, followed by summer, when particles would have a larger propensity to reach the southern area of the estuary (Samborombón Bay). Fall and winter are increasingly less favorable. All these features are consistent with patterns observed in the region in organisms having different life history traits. 相似文献
14.
On the basis of data of measurements carried out on an oceanographic platform, we study the variability of statistical characteristics of the modulus of slopes of the sea surface under various hydrometeorological situations. We show that the law of distribution of the modulus of slopes of the sea surface depends on the velocity of the wind and note that the empirical distribution differs considerably from the approximation proposed by Longuet-Higgins for it by the results of analysis of a Gauss random moving surface. The possible reasons for the difference in model and empirical distributions are discussed. 相似文献
15.
A. V. Glazunov 《Izvestiya Atmospheric and Oceanic Physics》2006,42(3):282-299
The neutrally stratified boundary layer over a smooth rough surface is consider. The turbulent flow is simulated using a finite-difference eddy-resolving model of the atmospheric boundary layer (ABL). The model includes different turbulence closure schemes and numerical approximations for advection components of the momentum balance equation. We investigate the quality of reproduction of spectral characteristics of the turbulent flow and the model’s capabilities to reproduce the observed profile of mean wind velocity near the rough surface. It is shown that the best result is obtained by coupling a numerical scheme of higher order of accuracy with a mixed closure scheme based on an adaptive estimation of the mixing length for subgrid-scale fluctuations. Here, we are able to reproduce the asymptotics of the fluctuation spectrum of the longitudinal component of wind velocity near the surface and within the boundary layer as well as the logarithmic profile of mean velocity near the surface. 相似文献
16.
海气动量通量研究综述 总被引：1，自引：0，他引：1
海气界面动量通量也称为风应力,是海流和表面海浪的主要驱动力,是海洋从大气获得动量的重要途径。因此,合理可靠的海洋表面风应力的参数化对于海洋、大气和波浪以及气候模式的准确预报都具有非常重要的科学意义和实用价值。对风应力拖曳系数的参数化是风应力参数化的主要内容。近来的观测发现,风应力拖曳系数随着风速的增加出现了先增后减的趋势,同时还与海面的波浪状态以及海流有关。基于观测或理论分析,目前已经得到了一系列的风应力拖曳系数计算方法或公式,有的考虑了海浪的作用,有的没有,但这些方案大都是适合中低风速,在高风速下的适用性还有待检验。本文回顾了目前在海气动量通量观测和参数化方面的研究进展,并建议应增加高风速下风速、海流以及海浪等的同步观测,以进一步完善风应力参数化方案。 相似文献
17.
The main features of a bistatic quasi-mirror radar of the sea surface are considered in an approximation of quasi-mirror scattering from isotropic surface waves. Surface-wave scattering plots determining the energetics and width of the view area of airspace radars are constructed under horizontal polarization and surface-radiating ray fall angles that are away from the nadir. We consider the factors determining the form of the “flare track”: projections of the difference-wave vector in the lateral and transversal directions; the rates of tilt of the wind waves; and the finite radius of the Earth’s curvature, which is important for ocean sounding from space. The resolution with respect to an axis of horizontal length is the worst at the mirror point; however, in most of the wide viewing area, this resolution is only a few times lower than the resolution of a conventional (monostatic) radar for the same width of the signal spectrum. We also consider the conditions for synthesizing the directional diagrams of a receiving antenna when there are two viewing areas that are not separated with respect to the slant range, as well as the influence that surface nonstationarity has on the synthetic aperture radar focusing. 相似文献
18.
利用IPCC-AR4气候模式诊断与比较计划(PCMDI)20C3M试验和A1B情景试验模拟数据,研究了在温室气体排放情景下,北太平洋海表面温度的变化及其对太平洋风应力旋度变化的响应。结果表明,温室气体中等排放A1B情景与20C3M情景相比,北太平洋年平均海表面温度表现为一致增温的趋势,且最大的增温中心位于黑潮及其延伸体区。与20C3M试验相比,CO2增加情景下北太平洋中部东风加强,增加向北的Ekman输送,使得北太平洋内区增温。风应力旋度零线也向北略有移动,导致黑潮延伸体向北移动并得到加强,从而引起延伸体区较强增温。风应力旋度零线的纬度附近产生的Rossby波,向西传播到黑潮延伸体区,进一步加强黑潮延伸体区的温度异常。海洋对北太平洋风应力场变化的局地响应及延迟响应,使黑潮延伸体海域海表面增温远大于周围海区。 相似文献
19.
Particle tracking experiments on a model of the Okhotsk Sea: Toward oil spill simulation 总被引：2，自引：1，他引：1
Particle tracking experiments were conducted for the Sea of Okhotsk using a three-dimensional ocean circulation model, as
a step toward the simulation of oil spills. The model’s reproducibility is first examined in detail. Comparison with surface
drifter and moored ADCP data shows that the model successfully reproduces the velocity field over the shelves, particularly
in the weak stratification period. This is because the current variability is simply determined by integration of the alongshore
component of the wind stress over the coast from which arrested topographic waves propagate. Good agreement even in the ice-covered
period implies that the neglect of sea ice in the model is not a problem for reproduction of the current over the shelves.
Good agreement also supports the correction of ECMWF wind speed by a factor of 1.25. A series of particle tracking experiments
was carried out to examine the case of particles released from the Sakhalin oil field at depths of 0 m and 15 m. Regardless
of the deployment month and year, most particles at depth 15 m are transported southward along the Sakhalin coast, in accordance
with the abrupt intensification of the East Sakhalin Current in October, finally arriving offshore of Hokkaido in November–January.
Particles at the surface, which are affected by wind drift in addition to the ocean current, show larger yearly variability.
In years when the offshoreward-wind dominates, the particles would be advected out of the mainstream of the current and would
not be transported offshore of Hokkaido. 相似文献
20.
JIANG Bo WEI Yongliang DING Jie ZHANG Rong LIU Yuxin WANG Xiaoyong FANG Yizhou 《海洋湖沼学报（英文）》2019,(5):1510-1522
Studies on climate change typically consider temperature and precipitation over extended periods but less so the wind. We used the Cross-Calibrated Multi-Platform (CCMP) 24-year wind fi eld data set to investigate the trends of wind energy over the South China Sea during 1988-2011. The results reveal a clear trend of increase in wind power density for each of three base statistics (i.e., mean, 90 th percentile and 99 th percentile) in all seasons and for annual means. The trends of wind power density showed obvious temporal and spatial variations. The magnitude of the trends was greatest in winter, intermediate in spring, and smallest in summer and autumn. A greater trend of increase was found in the northern areas of the South China Sea than in southern parts. The magnitude of the annual and seasonal trends over the South China Sea was larger in extreme high events (i.e., 90 th and 99 th percentiles) compared to the mean conditions. Sea surface temperature showed a negative correlation with the variability of wind power density over the majority of the South China Sea in all seasons and annual means, except for winter (41.7%). 相似文献