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大气波导是对流层中一种异常大气折射结构，它改变了电磁波的正常传播特性，严重影响了电子设备使用。目前对于大气波导的探测手段还比较单一，无法实现全类型大气波导的探测。针对这一现状，本文基于转动拉曼大气温度探测和振动拉曼大气湿度探测的原理，结合蒸发、表面和悬空波导的诊断方法，构建了全类型大气波导诊断模型。利用拉曼激光雷达新技术，实现了全类型大气波导的监测诊断。通过对比拉曼激光雷达和无线电探空仪测量数据，得到：拉曼激光雷达测量的大气温度廓线平均误差为0.535℃，温度误差小于1℃的概率为82.5%；水汽混合比廓线平均误差为0.121 7 g/kg，水汽混合比误差小于1 g/kg的概率为90%，基于拉曼激光雷达的悬空波导高度、厚度、强度诊断准确率分别为94.8%、85.8%和60%；此外，基于拉曼激光雷达的连续探测数据，可以进一步分析大气波导特征量随时间的变化规律。 相似文献
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张吟 《数字海洋与水下攻防》2023,6(4):450-457
阐述了机载激光雷达水下探测的原理与发展,包括激光雷达水下探测原理和激光雷达水下探测发展历程。对主要机载激光雷达水下探测系统进行了详细的分析,包括主流机载激光雷达测深系统及其发展趋势。在浅水小目标探测关键技术方面,对高功率密度激光器技术、高性能水下光学系统、大视场快速成像技术、小目标自主识别与精确定位技术和轻小型化技术等进行了剖析和总结。为进一步推进激光雷达水下高精度目标探测技术的发展提供参考和依据。 相似文献
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多普勒激光测风雷达是近年来方兴未艾的 1种全新的大气风场探测手段。但是激光测风雷达直接测量的是视线方向上的激光反射光的频移 (视线风速 )。在这个基础上 ,激光雷达还必须能够获得多方位的风速数据才能够反演出风场。这就需要相应的光学扫描系统 ,它在保证发射、接收视场重叠的前提下 ,控制激光束投射到指定的方向 ,使激光雷达获得不同视线角度的风速数据。本文介绍的激光雷达测风系统中的光学扫描部分实现了上述要求 ,在水平旋转和俯仰控制上的精度都达到了<0 .5°。完全能够满足激光测风系统的实用需要。 相似文献
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为了解决拍岸区水雷探测的问题，以无人机为载体的条纹管成像蓝绿激光雷达可以用来扫描、识别水雷，蓝绿激光成像雷达白天和夜晚均可以稳定成像，机载探测方式相对于水下、水面等传统探测方式效率也可以提高，机载激光雷达可由小型船舶、小型汽车等多平台携带使用。 相似文献
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《海洋气象学报》2019,(4)
2019年3月,利用相干多普勒测风激光雷达首次在辽东湾西部绥中地区进行了风廓线测量试验。根据研究区域海岸线走向采用风向的十六分位法定义局地海风和陆风,分析和提取海陆风特征验证了多普勒测风激光雷达在春季季风间断期间观测海陆风的可行性,并计算和分析了大气边界层湍流能量的变化以及回流水平变化等特性。结果表明:1)绥中地区春季存在明显的海陆风环流特征,测风激光雷达观测海陆风出现的时间与地面自动气象站观测的数据较为一致,符合海陆风日的定义。2)海陆风日发生时,水平局地回流指数(RF)较小,1. 2 km以下的RF值小于0. 5,使得污染物循环累积,较易形成雾霾天气;但是海风时大气边界层的高度可达1 km以上,有利于低层大气污染物向高层扩散,减轻低层大气污染。研究结果为该地边界层参数化方案的设计和污染的防治提供了参考依据。 相似文献
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西北太平洋的低云云顶高度(cloud top height,CTH)是气候研究和气象灾害监测中的重要参数。研究中常用卫星数据获得大范围、连续变化的低云云顶高度,但其与实际的低云云顶高度存在较大的偏差。因此,基于低云云顶一般在低层逆温层底这一观测现象,提出一种利用 FY-4A 卫星大气垂直廓线数据反演低云云顶高度的方法(称为“逆温法”),并尝试用于西北太平洋低云云顶高度反演研究。利用星载激光雷达 CALIPSO(Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation)探测的低云云顶高度,检验 FY-4A 卫星的云顶高度产品(CTHAGRI)和“逆温法”反演的低云云顶高度结果(CTHGIIRS ),表明两者均显著偏低,与 CALIPSO 探测的云顶高度差分别为 -0. 49 km和-0. 27 km,相较而言,“逆温法”反演的低云云顶高度更接近 CALIPSO 的探测结果,优于FY-4A卫星的云顶高度产品。 相似文献
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We have performed a simulation of the convectively induced ascent of the gas–dust cloud formed during the atmospheric passage and explosion of the Chelyabinsk meteoroid. The acceleration, velocity, and rise of the gas–dust cloud have been described as functions of time and altitude. The time of dust settling in the atmosphere has been estimated. The results of calculations are in a close agreement with the observational data. 相似文献
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A numerical algorithm for modeling the vertical propagation and breaking of nonlinear acoustic-gravity waves (AGWs) from the Earth’s surface to the upper atmosphere is described in brief. Monochromatic variations in the vertical velocity at the Earth’s surface are used as an AGW source in the model. The algorithm for solving atmospheric hydrodynamic equations is based on three-dimensional finite-difference analogues of fundamental conservation laws. This approach selects physically correct generalized solutions to hydrodynamic equations. A numerical simulation is carried out in an altitude region from the Earth’s surface to 500 km. Vertical profiles of the background temperature, density, and coefficients of molecular viscosity and heat conduction are taken from the standard atmosphere models. Calculations are made for different amplitudes of lower-boundary wave forcing. The AGW amplitudes increase with altitude, and waves may break in the middle and upper atmosphere. 相似文献
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Microwave remote sensing has become the primary means for sea-ice research, and has been supported by a great deal of field experiments and theoretical studies regarding sea-ice microwave scattering. However, these studies have been barely carried in the Bohai Sea. The sea-ice microwave scattering mechanism was first developed for the thin sea ice with slight roughness in the Bohai Sea in the winter of 2012, and included the backscattering coefficients which were measured on the different conditions of three bands(L, C and X), two polarizations(HH and VV), and incident angles of 20° to 60°, using a ground-based scatterometer and the synchronous physical parameters of the sea-ice temperature, density, thickness, salinity, and so on. The theoretical model of the sea-ice electromagnetic scattering is obtained based on these physical parameters. The research regarding the sea-ice microwave scattering mechanism is carried out through two means, which includes the comparison between the field microwave scattering data and the simulation results of the theoretical model, as well as the feature analysis of the four components of the sea-ice electromagnetic scattering. It is revealed that the sea-ice microwave scattering data and the theoretical simulation results vary in the same trend with the incident angles. Also, there is a visible variant in the sensitivity of every component to the different bands.For example, the C and X bands are sensitive to the top surface, the X band is sensitive to the scatterers, and the L and C bands are sensitive to the bottom surface, and so on. It is suggested that the features of the sea-ice surfaces and scatterers can be retrieved by the further research in the future. This experiment can provide an experimental and theoretical foundation for research regarding the sea-ice microwave scattering characteristics in the Bohai Sea. 相似文献
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Sound from an airborne source travels to a receiver beneath the sea surface via a geometric path that is most simply described using ray theory, where the atmosphere and the sea are assumed to be isospeed sound propagation media separated by a planar surface (the air-sea interface). This theoretical approach leads to the development of a time-frequency model for the signal received by a single underwater acoustic sensor and a time-delay model for the signals received by a pair of spatially separated underwater acoustic sensors. The validity of these models is verified using spatially averaged experimental data recorded from a linear array of hydrophones during various transits of a turboprop aircraft. The same approach is used to solve the inverse time-frequency problem, that is, estimation of the aircraft's speed, altitude, and propeller blade rate given the observed variation with time of the instantaneous frequency of the received signal. Similarly, the inverse time-delay problem is considered whereby the speed and altitude of the aircraft are estimated using the differential time-of-arrival information from each of two adjacent pairs of widely spaced hydrophones (with one hydrophone being common to each pair). It is found that the solutions to each of the inverse problems provide reliable estimates of the speed and altitude of the aircraft, with the inverse time-frequency method also providing an estimate that closely matches the actual propeller blade rate 相似文献
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Atmospheric correction of Landsat data for the retrieval of sea surface temperature in coastal waters 总被引：1，自引：0，他引：1
1IntroductionRemote sensingis an effective approach for esti-mation of the sea surface temperature(SST),andadvanced very high resolution radiometer(AVHRR)and moderate resolution imaging spectroradiometer(MODIS)thermal infared(TIR)data are widelyused in th… 相似文献
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The relay propagation of Gaussian--Schell-model in turbulent atmosphere along a slant path is studied in this paper. Based on the extended Huygens--Fresnel principle and a quadratic approximation, an analytical formula of average intensity for Gaussian--Schell-model beams in turbulent atmosphere along a slant path is derived, and some special cases are discussed. From the study and the comparison with the direct propagation, we can see that the relay propagation has an advantage over the direct propagation. When the altitude of the target is low, the peak intensity of relay propagation is much larger than that of direct propagation. However, because of the limitation of the relay system aperture for relay propagation and the variation of coherence length for direct propagation, the difference in peak intensity between the two propagations decreases with the increase of the target altitude. 相似文献
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多普勒天气雷达和L-波段探空雷达在探测中尺度天气方面,各有长处.前者具有较高的时空分辨率,缺点是需要反演.后者数据直接且要素多,但为局地数据,存在代表性的问题.利用多普勒雷达反演风廓线和300 m分辨率的探空数据相结合,可以很好的解释2006年8月26日发生在青岛的一次对流性暴雨过程的演变.在这次过程中,300 m分辨率的探空数据捕捉到了2 km左右高度上的冷平流信息,而多普勒雷达反演数据显示,温度平流对于对流的发生发展和消亡起着非常重要的作用.而且,多普勒雷达反演数据还揭示,在天气尺度影响系统仍然存在的背景下,冷平流的持续作用,引起了青岛上空大气状态的变化,导致整个降水过程结束. 相似文献