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排序方式: 共有78条查询结果,搜索用时 265 毫秒
61.
为改善非规则天线阵列综合孔径辐射计反演图像质量,提出了基于系统函数优化的亮温反演方法。通过优化非规则天线阵列的系统函数,消除单元天线非规则排列对系统性能的影响,并在优化过程中引入正则化,稳定反演图像。为补偿正则化引起的反演图像质量损失,在反演算法中引入了迭代运算。仿真结果表明:所提出的反演算法能有效改善非规则天线阵列综合孔径辐射计的亮温反演图像质量,可应用于基于小卫星编队的分布式综合孔径遥感图像反演中,并能为基于小卫星编队的分布式综合孔径阵列优化提供理论基础。 相似文献
62.
为验证镜像综合孔径微波辐射成像的原理,设计了V波段镜像综合孔径辐射成像原理实验系统(MAS-V),介绍了系统组成及原理并进行了电暖器辐射成像及空间分辨率实验,电暖器热辐射部分清晰可见,且轮廓与光学图像结果一致。实验结果表明:镜像综合孔径微波辐射成像的原理正确。对于相同的天线阵列,镜像综合孔径的空间分辨率优于常规综合孔径,约为其2倍。若增大反射板与天线阵列的距离,镜像综合孔径的空间分辨率将进一步提高。研究结果为镜像综合孔径微波辐射成像方法应用于静止轨道大气遥感提供了参考。 相似文献
63.
Eliana Vieira Clara Lázaro M. Joana Fernandes 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(5):1737-1753
Due to the presence of water vapour and cloud liquid water in the atmosphere, the wet component of the troposphere is responsible for a delay in the propagation of the altimeter signals, the Wet Path Delay (WPD). The high space–time variability of the water vapour distribution makes the modelling of WPD difficult, its effect still being one of the main error sources in satellite altimetry applications, e.g. in the estimation of Mean Sea Level (MSL). The understanding and the quantification of the WPD variability on various spatial and temporal scales are the main purposes of this study, in view to improve the MSL error budget. The dominant timescales of WPD variability and its correlation with Sea Level Anomaly (SLA) are examined. In these analyses, the atmospheric reanalysis ERA-Interim model from the European Centre for Medium-Range Weather Forecasts (ECMWF) is used to derive a global dataset of daily grids of WPD, spanning a 28-year period from January 1988 to December 2015. The Seasonal-Trend decomposition procedure based on Loess (STL) is used to extract precise WPD annual and interannual signals. Linear trends have been derived from the interannual time series and the contribution of each STL component was mapped globally, allowing the understanding of the WPD variability in spatial terms. The correlation between SLA and WPD is mapped and decomposed into seasons using monthly mean grids, for a period of 21-years, from January 1993 to December 2013.Aiming at inspecting the sensitivity of the results to the used data set, the WPD temporal analysis is extended to the data set provided by the Special Sensor Microwave Imager (SSM/I) and SSM/I Sounder (SSM/IS) Sensors. The WPD from SSM/I(S) is compared against those from the ERA-Interim and from the National Centers for Environmental Prediction (NCEP).Results show that climate phenomena, especially the El Niño Southern Oscillation (ENSO) are the cause for this high variability, since they affect the water vapour and temperature. The observed trends from ERA-Interim, computed globally and over ocean regions only, allow concluding that WPD is increasing with time by approximately 0.1?mm per year, and the maximum trends are observed for the Pacific North and Indian Oceans. High correlation between WPD and SLA is found over the western tropical Pacific.The comparison between WPD from SSM/I(S) and from ERA-Interim and NCEP, allows concluding that the trends computed using only the SSM/I(S) measurement points are substantially larger. 相似文献
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65.
冰云探测对气候预测有重要价值,但因冰云粒子的影响,传统气象观测方法很难有效观测气候。太赫兹波的信号带宽较宽、波束较窄,在冰云探测上比使用微波毫米波更具优势。太赫兹冰云探测仪作为被动接收设备,具有体积小、功耗小的特点,与成本低、研发周期短、可以实现组网观测的Cubesat卫星平台有较高的契合度。以冰云探测为背景,分析太赫兹冰云探测仪系统指标,设计874GHz接收机系统的链路。在确保接收机系统性能的同时注重简化链路,减少体积功耗,以适应Cubesat平台,并结合工程经验在链路设计时采取预留增益余量、加入隔离器增强匹配等措施保证工程上的可实现性。最后对接收机链路进行ADS仿真,仿真结果能够满足冰云探测仪对接收机指标的需求。 相似文献
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基于V isual Basic编程,设计了卫星精密测定轨中的实时气象采集与对流层延迟估算系统。利用实时采集ZQZ-A型自动气象站的温度、相对湿度、大气压等气象要素,采用Saastamoinen模型进行估算天顶方向对流层静力延迟和湿延迟,同时采用地基双波段微波辐射计测量大气水汽总量和云液态水总量,进而估算更高精度的湿延迟,在其有效时与模型计算的静力延迟相加,得到天顶方向总延迟;无效时采用模型计算的总延迟。最后将其投影到卫星方向得到总延迟。实际应用表明,设计的对流层延迟估算系统人机界面友好,具有易用性,能实时、稳定地为卫星精密测定轨提供服务。 相似文献
69.
Among many scientific objectives of lunar exploration, investigations on lunar soil become more and more attractive to the scientists duo to the existence of abundant 3He and ilmenite in the lunar soil and their possible utilization. Although the soil composition determination on the lunar surface is available by visible light spectrometer, γ/X-ray spectrometer etc, the evaluations on the total reserves of 3He and ilmenite in the lunar deep and on the thickness of the lunar soil are still impossible so far. In this paper, the authors first give a rough analysis of the microwave brightness temperature images of the lunar disc observed using the NRAO 12 Meter Telescope and Siberian Solar Radio Telescope; then introduce our researches on the microwave dielectric properties of lunar soil simulators; finally, discuss some basic relations between the microwave brightness temperature and lunar soil properties. 相似文献
70.
提出了一种基于相位补偿的二维干涉综合孔径辐射计近场成像算法.从干涉综合孔径辐射计的成像原理和近场应用情况出发,分析了快速傅里叶变换(FFT,Fast Fourier Transform)反演算法在近场条件下存在的问题,并采用相位补偿的方法,提出了一种近场数值反演算法.对点目标用FFT算法和近场成像算法进行了成像仿真,仿真结果表明近场成像算法比FFT算法具有更高的空间分辨率.用一套8mm波段二元干涉综合孔径辐射计对人工双点源场景进行了成像实验,实验结果证明了该近场算法的有效性. 相似文献