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1.
Using a high-resolution LES numerical model, we calculated the turbulent thermal convection for high ratios of horizontal and vertical sizes of the computational domain (26: 26: 1). The natural analog of the simulated process is a planetary boundary layer (PBL) of the atmosphere growing with height in the background of stably stratified overlying air layers over a horizontally homogeneous heated surface under a weak average wind. We obtained the spectral distributions of variances of fluctuations in potential temperature and velocity components in ranges corresponding to scales from a few tens of meters to a few tens of kilometers. We found energetically significant segments of the spectrum of large-scale fluctuations in the potential temperature for which the power dependences S ～ k ?1/3 and S ～ k ?4/3 are satisfied with good accuracy. We calculated the characteristic spatial scales of horizontal fluctuations in velocity and temperature. We obtained a dependence of these scales on the height of the growing convective PBL. We discuss the characteristic features of large-scale distributions in terms of the self-similarity of the growing boundary layer behavior. 相似文献
2.
3.
The WRF-ARW regional atmosphere circulation model has been used to reproduce a few episodes of cold intrusion and the Novorossiysk bora accompanied by the formation of the mesoscale cyclonic vortex over the Black sea, which can be clearly observed from satellite images of cloudiness. It has been shown that the vortex development is associated with the specific features of air flow around the northwestern edge of the Caucasus Mountains. We have estimated the vertical vorticity associated with the alongshore horizontal gradient of temperature. We have considered the field structure of wind velocity and temperature of the axisymmetric quasi-two-dimensional vortex generated in the coastal zone and displaced seaward after separating from the coast. With the background northerly wind, the coastal cyclonic circulation is not accompanied by the vortex separation from the coast. The specific feature of the development of the cyclonic vortex is the southeastern wind with velocities of up to 10 m/s in the Caucasus coastal area from Sochi to Sukhum. 相似文献
4.
A surf zone with large breaking waves produces more spray than do offshore regions. Latent heat of spray evaporation causes change in the surrounding temperature and wind velocity, resulting in further alterations in temperature, wind velocity and heat flux. Spray in a surf zone with large breaking waves may have unignorable effect on determination of a local meteorological field because of this interconnected relationship as well as its higher population than in the open ocean. In this study, the effects of the spray latent heat on a meteorological field were investigated. The authors propose a method for estimating latent heat of spray vaporization over the ocean. The method was applied to a meso-scale meteorological model to perform numerical experiments with consideration of heat flux by spray. Although the contribution of heat flux on the ocean was as small as 2.5%, fluctuations of air temperature and wind velocity increased over time due to the effects of spray. The fluctuations are thought to cause uncertainty in weather prediction. Numerical experiments with spray provided predictions of air temperature and wind velocity near a coast line that were consistent with observational data, especially when the population of spray droplets increased by two orders of magnitude as is often observed in a coastal area. 相似文献
5.
I. P. Chunchuzov S. N. Kulichkov P. P. Firstov 《Izvestiya Atmospheric and Oceanic Physics》2013,49(3):258-270
The nonlinear propagation of acoustic pulses from a point source of an explosive character (surface explosion or volcano) throughout the atmosphere with stratified wind-velocity and temperature inhomogeneities is studied. The nonlinear distortions of acoustic pulse and its transformation into an N-wave during its propagation to the upper atmosphere are analyzed in the context of a modified Burgers’ equation which takes into account a geometric ray-tube divergence simultaneously with an increase in both nonlinear and dissipative effects with height due to a decrease in atmospheric density. The problem of reflection of a spherical N-wave from an atmospheric inhomogeneous layer with model vertical wind-velocity and temperature fluctuations having a vertical spectrum that is close to that observed within the middle atmosphere is considered. The relation between the parameters (form, length, frequency spectrum, and intensity) of signals reflected from an atmospheric inhomogeneous layer and the parameters of the atmospheric fine layered structure at reflection heights is analyzed. The theoretically predicted forms of signals reflected from stratified inhomogeneities within the stratosphere and the lower thermosphere are compared to the observed typical forms of both stratospheric and thermospheric arrivals from surface explosions and volcanoes in the zones of an acoustic shadow. 相似文献
6.
S. N. Kulichkov I. P. Chunchuzov O. I. Popov 《Izvestiya Atmospheric and Oceanic Physics》2010,46(1):60-68
The results of simulating the influence of an atmospheric fine structure on the characteristics of acoustic signals propagating
throughout the atmosphere for long distances from their sources are presented. A numerical model of an atmospheric fine inhomogeneous
structure within the height range z = 20…120 km is proposed to perform calculations. This model and its numerical parameters are based on the current notions
of the formation of an atmospheric fine structure due to internal gravity waves. The numerical calculations were performed
using the parabolic-equation method. A spatial structure of the acoustic field and the structure of an acoustic signal at
long distances from a pulsed source were calculated. It is shown that the presence of an atmospheric fine structure results
in a scattering of acoustic signals and their recording in the geometric shadow region. The results of calculations of signal
forms are in a satisfactory agreement with data on signals recorded in the geometric shadow region which is formed at a distance
of about 300 km from an experimental explosion. 相似文献
7.
We perform the experimental verification of the applicability of the theory of similarity to the wave boundary layer and the
assessment of wave-induced perturbations of the air flow depending on various conditions of stratification of the atmosphere
and the state of the sea. The measurements were carried out from a stationary platform located in the coastal part of the
Black Sea. The experimental procedure is based on the simultaneous measurements of the profile and fluctuations of the wind
speed at 5–6 levels in the 1.3–21-m layer, the elevations of the sea surface, the directions of waves and winds, and the mean
gradients of temperature and humidity of air. The structure of the boundary layer in the region of measurements depends on
the direction of the wind. For weak and moderate onshore winds (< 9 m/sec), the approximate balance is preserved between the
production and dissipation of turbulent energy in the cases of unstable and neutral stratification. On the average, the estimates
of friction velocity according to the profiles are higher than the dissipative estimates by 10% mainly due to the deficiency
of dissipation near the surface. For the offshore wind, the structure of the boundary layer abruptly changes and is determined
not by the local parameters but by strong turbulent eddies formed over the dry land. The intensity of low-frequency turbulent
fluctuations and the gradient of wind velocity near the surface in the coastal zone are 1.5–2 times higher than for the open
sea.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 3, pp. 42–61, May–June, 2007. 相似文献
8.
S. N. Kulichkov I. P. Chunchuzov G. A. Bush V. G. Perepelkin 《Izvestiya Atmospheric and Oceanic Physics》2008,44(2):175-186
The results of experiments on the physical modeling of long-range infrasonic propagation in the atmosphere are given. Such modeling is based on the possible coincidence between the forms of the vertical profiles of the effective sound speed stratification in the atmospheric boundary layer (between 0 and 600 m for the case under consideration) and in the atmosphere as a whole (from the land surface up to thermospheric heights (about 150 km)). The source of acoustic pulses was an oscillator of detonation type. Owing to the detonation of a gas mixture of air (or oxygen) and propane, this generator was capable of producing short, powerful (the maximum acoustic pressure was on the order of 30 to 60 Pa at a distance of 50 to 100 m from the oscillator), and sufficiently stable acoustic pulses with a spectral maximum at frequencies of 40 to 60 Hz and a pulsing period of 20 to 30 s. The sites of acoustic-signal recording were located at different distances (up to 6.5 km) from the source and in different azimuthal directions. The temperature and wind stratifications were monitored in real time during the experiments with an acoustic locator—a sodar—and a temperature profiler. The data on the physical modeling of long-range sound propagation in the atmosphere are analyzed to verify the physical and mathematical models of predicting acoustic fields in the inhomogeneous moving atmosphere on the basis of the parabolic equation and the method of normal waves. A satisfactory agreement between calculated and experimental data is obtained. One more task was to compare the theoretical relations between variations in the azimuths and angles of tilting of sound rays about the horizon and the parameters of anisotropic turbulence in the lower troposphere and stratosphere with the experimental data. A theoretical interpretation of the experimental results is proposed on the basis of the theory of anisotropic turbulence in the atmosphere. The theoretical and experimental results are compared, and a satisfactory agreement between these results is noted. 相似文献
9.
Seasonal Variation of Space/Time Statistics of Short-Term Sea Surface Temperature Variability in the Kuroshio Region 总被引：1，自引：0，他引：1
Spatial and temporal scales of sea surface temperature (SST) variations in the Kuroshio region have been investigated using a satellite-based one-year merged SST product. Targeting short-term variations with temporal scales of less than a year, decorrelation scales, which are defined as the e-folding scale of SST variability, have been derived as functions of regional positions and calendar months. We assumed that the autocorrelation function of SST has anisotropic Gaussian characteristics in the space-time domain. Resultant spatial and temporal decorrelation scales range from 1 to 3° and 2 to 3 days, respectively. They are strongly inhomogeneous, anisotropic and time-dependent. These characteristics are attributed to the oceanic and atmospheric disturbances. Spatial decorrelation scales are determined mainly by strong atmospheric forcing in the study region. In the area with dominant atmospheric forcing, the spatial scales are larger than those in the other regions. Those in the regions with dynamical oceanographic disturbances are as small as 1°. Signal-to-noise ratios are also large where the atmospheric forcing is strong, while they are small where the oceanic signals are active. 相似文献
10.
I. P. Chunchuzov V. G. Perepelkin O. E. Popov S. N. Kulichkov A. A. Vardanyan G. Y. Ayvazyan Kh. Z. Khachikyan 《Izvestiya Atmospheric and Oceanic Physics》2017,53(3):279-293
Results of acoustic sounding of the lower troposphere with the aid of detonation generators of acoustic pulses are given. This sounding method is based on a partial reflection of acoustic pulses with shock fronts from vertical wind-velocity and temperature gradients continuously varying with height in the troposphere and on the penetration of reflected signals into the region of acoustic shadow. Experiments on tropospheric sounding were carried out on the ground of the Barva Innovation Scientific and Technical Center (Talin, Armenia) in September 2015. In these experiments, an antihail acoustic system was first used as a generator of acoustic pulses. Experimental results have been compared with data obtained earlier in similar experiments carried out in the vicinity of Zvenigorod with the use of a special detonation generator of acoustic pulses. Due to the high resolution (in height) of the sounding method, which reaches 1 m in the stably stratified lower troposphere within a height range of 250–600 m, the vertical profiles of layered effective sound speed inhomogeneities with vertical scales from a few to a few tens of meters have been retrieved. The influence of these fluctuations on the form and amplitude of acoustic signals at a long distance from their pulsed source has been studied. 相似文献
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12.
V. F. Ivanov 《Physical Oceanography》1990,1(5):369-376
Taking into consideration stratification, the mean current velocity, and the tangential wind stress expressed in terms of air pressure fluctuations, we have derived iteration formulae and have performed computations of the amplitudinal characteristics of oceanic internal waves generated by air pressure waves of semi-diurnal and 4-day long periodicity propagating over the Tropical Atlantic Ocean. It has been demonstrated that such periodicity and wavelengths may contribute to the generation of long-amplitude internal waves, whose intensity is largely dependent on the direction of atmospheric wave propagation.Translated by Vladimir A. Puchkin. 相似文献
13.
利用 POM(Princeton Ocean Model)海洋数值模式建立渤、黄、东海冬季三维环流动力学区域模型。模型在海-气边界使用包括风应力、气压和热通量的大气驱动, 海洋边界使用西太平洋模式提供的环流和潮位驱动, 综合模拟潮波运动、温度、盐度、环流变化和水位低频波动。 模拟了 2001 年 1 月寒潮过境时黄、 渤海水位低频波动及流场变化, 分析了其对大风过程、 气压、降温的响应, 发现冬季强劲的北风和西北风都可以通过抽吸振荡在渤、 黄海诱发水位的低频波动, 东北风则由于地形影响不能诱发渤、黄海的低频波动。气压和降温只是在波动幅度上有一定的影响。波动发源于渤海和北黄海, 最大波幅可以达到 0.6 m。波动进入南黄海后有沿黄海深槽西侧传播的倾向, 波动幅度在传播过程中逐渐减小。 相似文献
14.
深海海面目标单水听器被动测距方法与验证 总被引：1，自引：1，他引：0
基于射线理论分析了在深海情况下海面声源产生声场的频率-距离干涉结构,给出了影区内声场频率-距离干涉结构的近似理论表达式,分析得到影区内声场频域干涉周期随收发距离的增加而增大、随着接收水听器深度的增加而减小。因此由单水听器记录的声场干涉结构即可实现被动声源距离估计。在南海深海实验中观测到海面宽带噪声源在声场影区形成的声场干涉结构,对实验获得声场干涉结构的处理结果验证了深海声场影区干涉结构用于被动声源距离估计的有效性。与传统的匹配场被动定位方法相比,该方法不需要已知海底声学参数和大规模的拷贝场计算。 相似文献
15.
Mapping climatic temperature changes in the ocean with acoustictomography: navigational requirements
Spiesberger J.L. Fabrikant A.L. Silivra A.A. Hurlburt H.E. 《Oceanic Engineering, IEEE Journal of》1997,22(1):128-142
In eddy-resolving hydrodynamic models, first-mode baroclinic Rossby waves linked to El Nino/Southern Oscillation are the dominant features which change basin-wide temperatures below the seasonal thermocline in the northeast Pacific at periods less than a decade. Simulations are carried out in which Rossby waves are mapped using acoustic tomography. Based on the model which propagated these waves, a Kalman filter is used to map temperature signals for a year. The modeled data are taken from a dense network of acoustic tomography sections. At 300-m depth, where the temperature perturbations associated with Rossby waves are about ±1°C, 80% to 90% of the model variance is accounted for with tomographic estimates. The corresponding standard deviations of the estimates are less than 0.1°C at 400-km resolution. About 80% of the model variance is accounted for with tomography when the navigational errors of the sources and receivers are as poor as one kilometer. Consequently, it may be unnecessary to accurately navigate actual tomographic instruments to map climate change. Modeling results are insensitive to: 1) a reduction in data due to a significant number of instruments which fail; 2) whether the instruments are mobile or fixed; 3) the detailed trajectories of mobile receivers; 4) the shape of the a priori spectrum of ocean fluctuations; 5) the corrections to the acoustic travel-time biases; and 6) the errors in the sound-speed algorithm. In basin-scale arrays, the modeled variance of acoustic travel time depends on the horizontal wavenumber of temperature as k-5.5. Because sound has little sensitivity to small wavelengths, modeled Rossby waves can be mapped in a day from a few sources and of order ten receivers. The results only depend on the model having large scales in space and time 相似文献
16.
V. N. Kozhevnikov K. B. Moiseenko B. I. Volkov 《Izvestiya Atmospheric and Oceanic Physics》2016,52(6):587-595
The dependence of orographic disturbances of the atmosphere on properties of the incident flow is studied within the semianalytic approach. Reducing the initial system of equations of hydrothermodynamics to a single equation for an associative stream function makes it possible to consider a class of solutions of a sufficiently general type when the background velocity of the wind and the Lyra’s scale vary with height. It is shown that the dependence of the solution on the indicated factors can be not only strong, but also sufficiently unexpected. In particular, with the monotonic growth in the wind velocity in the troposphere, which corresponds to conditions of a jet stream near the tropopause, disturbances at low and medium heights can acquire an almost resonant and waveguide nature. 相似文献
17.
Ｎｕｍｅｒｉｃａｌｔｅｓｔｏｆｃｏａｓｔａｌｆｒｏｎｔｏｇｅｎｅｓｉｓ￥ＳｈｅｎＳｈａｏｈｕａａｎｄＺｈｏｕＭｉｎｇｙｕ（ＲｅｃｅｉｖｅｄＦｅｂｒｕａｒｙ８，１９９３；ａｃｃｅｐｔｅｄＭａｒｃｈ３０，１９９３）Ａｂｓｔｒａｃｔ：──Ａｔｗｏ－ｄｉｍｅ... 相似文献
18.
A. S. Gurvich V. V. Vorob’ev O. V. Fedorova 《Izvestiya Atmospheric and Oceanic Physics》2006,42(4):463-473
Observation of stars from a spacecraft through the Earth’s atmosphere is a constituent part of remote sensing of the atmosphere. Recorded scintillation signals contain data on the structure of air-density irregularities induced by turbulence and internal waves. Currently, parameters of the structure in the stratosphere are determined using the procedures based on the weak-scintillation theory. However, during stellar occultation by the Earth’s atmosphere, scintillation becomes stronger as the line of sight plunges into denser air layers. This paper considers the problem of remote sensing of stratospheric irregularities under strong-scintillation conditions. The scintillation spectra are calculated in the phase-screen approximation under the assumption that the spectrum of the phase added by the screen corresponds to observations through the stratosphere. It is assumed that stratospheric irregularities of air density are generated by an ensemble of saturated internal waves whose three-dimensional spectrum contains two characteristic wave numbers corresponding to the outer and inner scales. In the calculation, no restrictions are imposed on the observed scintillation amplitude. It is shown that the effect of the scintillation amplitude on the observed scintillation spectra appears most prominent for large wave numbers corresponding to irregularities whose sizes are smaller than the inner scale. For these wave numbers, deviations from the weak-scintillation theory become appreciable if the rms relative fluctuation of light intensity exceeds 0.3. In contrast, for small wave numbers corresponding to scales exceeding the outer scale, the weak-scintillation theory remains valid to rms values as large as 2. Analysis of calculated spectra has shown that the parameters of the three-dimensional spectra of stratospheric irregularities can be retrieved under the conditions of relatively strong scintillation characterized by an rms value below 1.5–1.6. 相似文献
19.
海—气相互作用与海流、风暴潮 总被引：3，自引：4，他引：3
从方法论上说,除潮汐以外,通常在处理海洋动力学问题时,大多撇开海洋对大气的影响,强调大气对海洋的主导作用,把大气运动当作诱发海水运动的唯一原动力,视海面风场为给定条件,而后用经验或半经验公式算出海面风应力场,作为施加于海水的强迫力。因此,一个成功的海浪、海流或风暴潮的预报,除了具备反映海水运动的主要物理性能的数学模型外,还必须以客观的、准确的海面风场的数值计算和预报为前提。由于问题的复杂性,迄今为止似乎还不能说在实用上已经提供了海面风的一种足够精确的估算或预报方法。海上气象观测资料,尤其是测风资料的稀少,给海面风应力的实际计算带来不少困难。 相似文献
20.
I. P. Chunchuzov S. N. Kulichkov O. E. Popov V. G. Perepelkin 《Izvestiya Atmospheric and Oceanic Physics》2010,46(5):597-607
A wave theory of propagation of an acoustic pulse in a moving stratified atmospheric layer above the ground with a finite
impedance of an underlying ground surface is developed. The shapes of acoustic signals in a near-ground atmospheric waveguide,
which are formed due to temperature inversion and a vertical shear of the wind velocity, are calculated based on this theory.
These signals are compared with those measured during the experiments where vertical profiles of the wind velocity and temperature
in an atmospheric boundary layer have been continuously controlled using a sodar, a temperature profile meter, and acoustic
anemometers or thermometers mounted on a 56-meter-high mast. The joint action of a near-ground acoustic waveguide, the impedance
of the underlying surface, and a vertical layered structure of the boundary atmospheric layer on a signal shape far from the
acoustic source are studied. 相似文献