共查询到20条相似文献，搜索用时 671 毫秒
1.
D. M. Ermakov E. A. Sharkov I. V. Pokrovskaya A. P. Chernushich 《Izvestiya Atmospheric and Oceanic Physics》2013,49(9):974-985
The trajectory characteristics and the intensity evolution of the Alberto tropical cyclone (TC) in the integral water-vapor field are analyzed in detail using a software-algorithmic complex designed for constructing highly detailed global radio-thermal fields of the ocean-atmosphere system based on microwave satellite measurements. This complex was developed by the authors earlier and allows one to obtain global animated radio-thermal fields with a time step of 1.5 h and a spatial resolution of 0.2°. Special attention is paid to the problem of revealing the energy sources of three consecutive intensifications of this TC. The analysis of satellite data with the use of the animation method developed by the authors shows for the first time that these sources are regions with an increased (exceeding the critical level) integral water-vapor content located in different geographical areas lying along the complex trajectory of the TC with a variable intensity. The first region was located in the equatorial intertropical convergence zone, the second was located above the Gulf Stream water area, and the third resided in the area affected by the Azores High. 相似文献
2.
Very Large Eddy Simulation of Cavitation from Inception to Sheet/Cloud Regimes by A Multiscale Model
The cavitating flow in different regimes has the intricate flow structure with multiple time and space scales. The present work develops a multiscale model by coupling the volume of fluid(VOF) method and a discrete bubble model(DBM), to simulate the cavitating flow in a convergent-divergent test section. The Schnerr-Sauer cavitation model is used to calculate the mass transfer rate to obtain the macroscale phase structure, and the simplified Rayleigh-Plesset equation is applied to simulate the growing and collapsing of discrete bubbles. An algorithm for bridging between the macroscale cavities and microscale bubbles is also developed to achieve the multiscale simulation. For the flow field, the very large eddy simulation(VLES) approach is applied. Conditions from inception to sheet/cloud cavitation regimes are taken into account and simulations are conducted. Compared with the experimental observations, it is shown that the cavitation inception, bubble clouds formation and glass cavity generation are all well represented, indicating that the proposed VOF-DBM model is a promising approach to accurately and comprehensively reveal the multiscale phase field induced by cavitation. 相似文献
3.
A classification of sea ice in the Arctic by age (multiyear; first-year; and first-year deformed ice, nilas, etc.) is developed based on the Bayesian approach using satellite radar data and taking into account regional peculiarities of these types of ice for different sectors of the Arctic. Estimations of a priori probabilities for each ice type, which are required for the use of the Bayesian classification, are obtained by the analysis of ice charts in the Arctic seas developed at the AARI in 2008–2013 using satellite data. A posterior probabilities are estimated visually by an expert. Types of sea ice distinguished by the expert on satellite images make it possible to create sample values of the radar-scattering cross section (RSCS). Examples of the proposed Bayesian classification of ice in the Laptev Sea according to Envisat satellite data are given. 相似文献
4.
D. M. Ermakov E. A. Sharkov A. P. Chernushich 《Izvestiya Atmospheric and Oceanic Physics》2017,53(9):973-978
This paper is focused on the development of a methodological basis for the authors’ approach to the processing of large volumes of satellite radiothermal data, which is known as satellite radiothermovision. A closed scheme for calculating the latent heat flux (and other integral characteristics of the dynamics of geophysical fields) through arbitrary contours (boundaries) has been constructed and mathematically described. The opportunity for working with static, as well as movable and deformable boundaries of arbitrary shape, has been provided. The computational scheme was tested using the example of calculations of the atmospheric advection of the latent heat from the North Atlantics to the Arctic in 2014. Preliminary analysis of the results showed a high potential of the approach when applying it to the study of a wide range of synoptic and climatically significant atmospheric processes of the Earth. Some areas for the further development of the satellite radiothermovision approach are briefly discussed. It is noted that expanding the analysis of the available satellite data to as much data as possible is of considerable importance. Among the immediate prospects is the analysis of large arrays of data already accumulated and processed in terms of the satellite radiothermovision ideology, which are partially presented and continuously updated on a specialized geoportal. 相似文献
5.
Recent studies, both based on remote sensed data and coupled models, showed a reduction of biological productivity due to vigorous horizontal stirring in upwelling areas. In order to better understand this phenomenon, we consider a system of oceanic flow from the Benguela area coupled with a simple biogeochemical model of Nutrient-Phyto-Zooplankton (NPZ) type. For the flow three different surface velocity fields are considered: one derived from satellite altimetry data, and the other two from a regional numerical model at two different spatial resolutions. We compute horizontal particle dispersion in terms of Lyapunov exponents, and analyzed their correlations with phytoplankton concentrations. Our modeling approach confirms that in the south Benguela there is a reduction of biological activity when stirring is increased. Two-dimensional offshore advection and latitudinal difference in primary production, also mediated by the flow, seem to be the dominant processes involved. We estimate that mesoscale processes are responsible for 30–50% of the offshore fluxes of biological tracers. In the northern area, other factors not taken into account in our simulation are influencing the ecosystem. We suggest explanations for these results in the context of studies performed in other eastern boundary upwelling areas. 相似文献
6.
《Coastal Engineering》1999,38(3):143-166
Two different concepts are applicable to model the nearshore morphodynamics. The first one takes into account only final consequences of acting mechanisms and is aimed at the prediction of long-term trends in beach development. Another approach implies the modelling of the whole suite of elementary processes responsible for changes in nearshore bottom topography during a given storm, and it is the approach used in the present work. A coastal area model complex is proposed that allows to reproduce the local morphological changes due to both the natural processes and the influence of coastal structures, such as a groin, a detached breakwater and a navigable channel (underwater trough). Consisting of a traditional series of basic components, the model differs from other ones in essential aspects concerning the treatment of transport mechanisms. In particular, the determination of wave-induced near-bed mean flow is based on the hypothesis that the direction and magnitude of bottom drift depend on difference between the actual rate of energy dissipation and its threshold value marking the flow reversal point. This hypothesis is shown to explain a general trend of cross-shore mean flow distributions observed in the nearshore region. Besides, the influence of the wave breaking process on sediment suspension is taken into account and the contribution of the swash zone to total sediment transport is included. Examples of computed morphological response are represented to demonstrate the model capability. A satisfactory agreement of computations with available data is pointed out. 相似文献
7.
A theoretical analysis of the principal oceanic ring parameters (tangential and angular velocities, shape function, horizontal and vertical scale of the ring) is described. The theoretical model consists of a reduced gravity model of the lens-like vortices with solid body rotation. The application of this approach is tested by comparison with data from the North Brazil Current Rings Experiment and remote sensing data. Specifically, we used the data corresponding to the surfaceintensified North Brazil Current ring (R-3) surveyed in February–March 1999, using direct velocity and hydrographical measurements. The theoretical model was used for evaluating the geometrical structure of the surface-intensified rings that produce remarkable signals in satellite data. The principal ring parameters from the model were compared with those from satellite data (altimetry and drifter information), which were estimated by using the method of minimization of the multivariable objective functions. Although the proposed model is linear in its conception, a good agreement was observed between the model and the primary characteristics of the observed rings. The model, however, allows for improvement in its assumptions, since its application is rather limited to intense ocean rings. 相似文献
8.
The authors propose to treat the structure of the sea surface images from the ocean color scanners (OCS) as a complex integrated
indication of the state of the marine environment. Supposedly, such an approach will make current the information on the water
environment processes hidden in the spectral-radiance patterns of arbitrary shapes. They are typical of inland seas, straits,
and other transition areas but attract no attention due to recognition difficulties. The authors give preliminary estimates
of the repeatability of mesoscale structures found from data of the OCSs SeaWiFS and MODIS for the period of 1998–2007 in
the oceanologically diverse Caspian Sea regions. The authors’ approach is shown to be useful for studying the long-term variability
of marine aquatic areas from the satellite data archives. 相似文献
9.
Two methods for the investigation of suspended particulate matter (SPM) transport in the North Sea are presented: numerical modeling and remote sensing by satellite. The principles and the main components of the two methods are outlined. The numerical model uses a particle tracer method for the simulation of advective transport. It takes into account the interaction with the sediment bed (deposition, erosion). Remote sensing uses data of the Coastal Zone Colour Scanner (CZCS). The physical background of remote sensing is outlined and an inverse modeling procedure for evaluation of the satellite images is described. Data obtained with the two methods are compared with each other and with ship measured data which shows the strong and the weak points of each method. The combined use of field measurements, satellite observations, numerical modeling and specific in situ process studies is recommended as the most effective way to investigate SPM transport 相似文献
10.
ATOVS反演数据在大气中尺度模式MM5中的同化试验 总被引：1，自引：1，他引：0
基于中国海洋大学卫星地面站接收到的NOAA系列卫星数据,利用1种神经网络反演方法获取大气温度、湿度及风矢量垂直廓线数据。以2004年第14号台风"云娜"为例,在中尺度气象模式MM5中运用松弛逼近法对这些反演数据进行了一系列同化试验。结果表明:仅同化温度与湿度的效果比同时同化风矢量、温度与湿度的效果好;台风的路径与强度有所改善,不采用人造涡旋方案时同化效果相对采用人造涡旋方案时更能体现出改进作用。 相似文献
11.
Ya. A. Virolainen Yu. M. Timofeyev A. V. Poberovsky 《Izvestiya Atmospheric and Oceanic Physics》2013,49(9):993-1001
Ozone total column (OTC) measurements made in 2009–2012 near St. Petersburg by a Fourier Transform Infrared (FTIR) spectrometer (Peterhof, St. Petersburg State University (SPbSU)), an M-124 filter ozonometer, and a Dobson spectrophotometer (Voeikovo, MGO), as well as measurements made by a spectrometer ozone monitoring instrument (OMI) (onboard the AURA satellite) have been analyzed and compared. Comparisons have been performed both between ensembles of ground-based measurement data, as well as between ground-based and satellite data. It has been shown that the standard deviation for all devices is 2.5–4.5%; here, the FTIR and Dobson instruments measuring the direct sun are in better agreement with OMI than the M-124 ozonometer measuring the zenith-scattered solar radiation as well. A seasonal cycle in discrepancy with amplitude of 1.5% has been detected between two series of OTC measurements made by M-124 and OMI instruments for a total of 850 days. In fall and winter, the ground-based measurements underestimate the OTC values in comparison with satellite data; in spring and summer, the situation is reversed: ground-based data overestimate the OTC values. Also, it has been revealed that FTIR measurements systematically overestimate the OTC values in comparison with other instruments: from 1.4% (for Dobson) to 3.4% (for OMI). Taking into account the spatial and temporal discrepancy of independent ensembles of measurements and an analysis of standard deviations between ground-based and satellite measurement data, the FTIR spectrometer (SPbSU) can be recommended for OTC satellite data validation. 相似文献
12.
Coral reefs are an sensitive-to-environment complex marine ecosystem. The ecosystem of corals is rich in biodiversity. Remote sensing offers a powerful tool for categorizing coral reefs and is the most cost-effective approach for the large-scale reef survey. The Dongsha Atoll, more than 300 km2 with an average depth of 10 m, is located at the northern continental margin of the South China Sea. It has been abused by destructive fishing during recent decades. Three satellite imageries (Quickbird2, ETM and SPOT5) are used to evaluate the capabilities of SPOT5 imagery to provide data that are useful for categorizing the current distribution of coral reefs therein. During the data processing, unsupervised classification functions are adopted for ETM and SPOT5 data, while the supervised classification method is used for Quickbird2. The classes are (or not) merged into coral reef, and then will be operated by vectorization, simplification, and topological analysis. There are 1 331 coral reefs larger than 100 m2 with a detection limit of 3×3 pixels at the multi-band data of Quickbird2, which is taken as the comparison baseline. The results extracted from SPOT5 and ETM images are less in number and area than those from the Quickbird2 image, whereas the results from SPOT5 data are better than those of ETM data at the silty lagoon due to its higher resolution. SPOT5 XS band 2 fails to distinguish the deep substrate inside the atoll compared with ETM data because of its poor penetration capability. Only SPOT XS band 1 cannot be used to differentiate coral reef from sand bottom. Merging the SPOT5 multi-bands data with the spatial resolution of SPOT5 pan-data and referring to ETM imagery are expected to provide an optimal satellite-based approach for mapping of coral reefs. 相似文献
13.
X. San Liang 《海洋学报(英文版)》2008,27(Z1):74-92
This paper summarizes the recent development of a portable self-contained system to unravel the intricate multiscale dynamical processes from real oceanic flows, which are in nature highly nonlinear and intermittent in space and time. Of particular focus are the interactions among largescale, mesoscale, and suhmesoscale processes. We first introduce the concept of scale window, and an orthogonal subspace decomposition technigue called multiscale window transform (MWT). Established on MWT is a rig- orous formalism of multiscale transport, perfect transfer, and multiscale conversion, which makes a new methodology, multi- scale energy and vortieity analysis (MS-EVA). A direct application of the MS-EVA is the development of a novel localized in- stability analysis, generalizing the classical notion of hydrodynamic instability to finite amplitude processes on irregularly varia- ble domains. The theory is consistent with the analytical solutions of Eady' s model and Kuo' s model, the benchmark models of baroclinic instability and barotropic instability; it is further validated with a vortex shedding control problem. We have put it to application with a variety of complicated real ocean problems, which would be otherwise very difficult, if not impossible, to tackle. Briefly shown in this paper include the dynamical studies of a highly variable open ocean front, and a complex coastal o- cean circulation. In the former, it is found that underlying the frontal meandering is a convective instability followed by an abso- lute instability, and correspondingly a rapid spatially amplifying mode locked into a temporally growing mode; in the latter, we see a real ocean example of how upwelling can be driven by winds through nonlinear instability, and how winds may excite the ocean via an avenue which is distinct/y different from the classical paradigms. This system is mathematically rigorous, physically robust, and practically straightforward. 相似文献
14.
Methods for processing satellite data on ice features that pose a threat to the safety of offshore operations in the Arctic seas are considered. They are divided into interactive, automated, and automatic methods. The methods are illustrated by examples of archival satellite data on the Russian Arctic sector. Radar and optical data have been used as the satellite information source. It is shown that the successful satellite monitoring of dangerous ice features requires the optimal combination of satellite observations at various stages that provide for a synergistic approach to the data assimilation of different spectral bands obtained using different spacecraft. 相似文献
15.
大洋中涌浪普遍存在且对大气-海洋之间的物理过程有较大影响,但目前对涌浪的耗散过程研究尚不充分。总结了关于涌浪传播和耗散的观测事实,着重指出利用遥感数据推进相关研究的可能性;同时分析可能的物理机制,并论述其在海浪模式中的应用及不足。通过梳理大洋涌浪耗散的研究进展,为今后开展涌浪相关研究提供依据。 相似文献
16.
17.
The HY-1A satellite is the first oceanic satellite of China. During the winter of 2002～2003, the data of the HY-1A were applied to the sea ice monitoring and forecasting for the Bohai Sea of China for the first time. The sea ice retrieval system of the HY-1A has been constructed. It receives 1B data from the satellite, outputs sea ice images and provides digital products of ice concentration, ice thickness and ice edge, which can be used as important information for sea ice monitoring and the initial fields of the numeric sea ice forecast and as one of the reference data for the sea ice forecasting verification. The sea ice retrieval system of the satellite is described, including its processes, methods and parameters. The retrieving results and their application to the sea ice monitoring and forecasting for the Bohai Sea are also discussed. 相似文献
18.
The paper summarizes the results of the long-term complex satellite monitoring of the Black and Baltic seas. Data from synthetic aperture radars (SARs) constitute the experimental basis for the investigation of satellite. In addition to radar data, the data of the visible and infrared bands from MODIS Terra/Aqua, MERIS Envisat, Landsat series sensors are used. The features of the manifestation of hydrodynamic processes, submesoscale eddies in particular, in satellite radar and optical images in a period of intense phytoplankton bloom are discussed. A relationship is established between the intensity and duration of the phytoplankton bloom in the regions of observation and the frequency of the appearance of long-lasting wakes behind moving ships in SAR images. These wakes appear as long narrow bright bands of enhanced backscattered signal extending for tens and sometimes hundreds of kilometers. It is proposed to consider the wakes of this type as indicators of the areas and duration of intense phytoplankton bloom. Satellite observations over the Black and Baltic Seas conducted for more than ten years have shown that long-lasting ship wakes are influenced by powerful jet streams, such as those associated with the passage of eddies that leads to shifts and deformations. By comparing the true route of a ship with its wake in the satellite image, it is possible to obtain detailed information about the parameters of currents. 相似文献
19.
A new approach to assessing the risk of the impact of the thermokarst process on engineering constructions is considered; the approach is based on satellite observation data and methods of the mathematical morphology of landscape. The equations for risk assessment are derived for linear and areal constructions for processes with the Poisson distribution of free-form thermokarst sites. Testing areas with thermokarst lakes have been digitized and theoretical assumptions and empirical data are examined for agreement between them. 相似文献
20.
The HY-1A satellite is the first oceanic satellite of China. During the winter of 2002-2003, the data of the HY-1A were applied to the sea ice monitoring and forecasting for the Bohai Sea of China for the fhst time. The sea ice retrieval system of the HY-1A has been constructed. It receives 1B data from the satellite, outputs sea ice images and provides digital products of ice concentration, ice thickness and ice edge, which can be used as important information for sea ice monitoring and the initial fields of the numeric sea ice forecast and as one of the reference data for the sea ice forecasting verification. The sea ice retrieval system of the satellite is described, including its processes, methods and parameters. The retrieving results and their application to the sea ice monitoring and forecasting for the Bohai Sea are also discussed. 相似文献