HY-2卫星高度计电离层延迟误差与分析
发布时间：2019-03-20 19:03
【摘要】：卫星雷达高度计(Satellite radar altimeter)是海洋实时监测的一个重要工具。到目前为止,全世界已有不少国家发射了载有雷达高度计的卫星。星载雷达高度计的测高具有全天候全天时和全球范围探测能力,能时刻监测和观察海洋环境,获得包括有效波高值、风速、海表面温度等多种海洋动力环境参数,并直接为灾害性的海况预警预报提供实时监测数据;也为海洋环境保护、海洋资源开发、海洋防灾减灾、海洋科学研究以及国防建设等提供权威的支撑服务。基于这些因素,我国也于2011年发射了HY-2卫星。通过对HY-2(海洋2号)卫星工作原理的深研究,我们对星载雷达高度计测高的各个环节可能存在的误差有了深入的了解。本文主要针对国家海洋局海上环境预报中心所提供的数据,对测高过程中回波波形因素和电离层对信号的延迟误差及其修正给出了分析和研究。首先,为计算海洋海平面的高度,根据已有的模型对星载雷达高度计的回波波形进行跟踪和分析,找出影响回波波形的各种因素,利用回归分析和离散点交叉算法得出卫星轨迹的交叉点,并进行相应的标定;其次,利用几种插值算法计算各交叉点上有效波高、海洋风速和海平面高度,分析比较不同差值方法的结果得到最优差值方法;最后,针对国家海洋局海上环境预报中心所提供的数据分析了电离层延迟误差,对比了已知的几种电离层模型与自身双频改正效果,结果表明GIM模型改正效果最好,并建议在双频改正效果不理想的地方采用GIM模型改正。此外,本文用时间序列分析中滤波原理,对有效波高进行去燥处理得出信噪比较高的波形数据,利用这些数据可以进而对脉冲信号与海面作用误差即电磁偏差进行分析;电离层延迟的误差主要是由于电磁信号在电离层中传播发生折射造成的,可以通过采用双频(Ku波段和C波段)测量模式来降低电离层的影响,利用贝叶斯统计理论对这两波段(Ku波段和C波段)测高噪声进行均方差处理,使电离层延迟误差减少到厘米以内。同时,采用上述方法对T/P和JASON-1,2系列卫星数据进行处理,将所得到的结果与HY-2A卫星数据处理结果进行比较,方便寻找误差来源进而减少误差以及分析模型的优劣程度。海洋雷达测高卫星测高数据的误差分析和标定对测高数据的应用具有重要作用,随着HY-2A卫星的数据处理技术的不断改进,相应的误差分析也要随之改进,进而提高测高精度,提高卫星数据的科学应用价值。
[Abstract]:Satellite radar altimeter (Satellite radar altimeter) is an important tool for real-time ocean monitoring. So far, many countries around the world have launched satellites carrying radar altimeter. Space-borne radar altimeter with all-weather altimeter? Full-time and global detection capability to monitor and observe the marine environment at all times, and to obtain a variety of marine dynamic environmental parameters, including effective wave height, wind speed, sea surface temperature, and so on. It also directly provides real-time monitoring data for early warning and forecasting of disastrous sea conditions. It also provides authoritative support for marine environmental protection, marine resources development, marine disaster prevention and mitigation, marine scientific research and national defense construction. Based on these factors, China also launched the HY-2 satellite in 2011. Through the deep study of the working principle of the HY-2 satellite, we have a deep understanding of the possible errors in the altimeter height measurement of the spaceborne radar. Based on the data provided by the Marine Environment Forecast Center of the State Oceanic Administration, the factors of echo waveform and the delay error of ionosphere signal during altimetry and their correction are analyzed and studied in this paper. Firstly, in order to calculate the sea level height, the echo waveforms of spaceborne radar altimeter are tracked and analyzed according to the existing models, and various factors affecting the echo waveforms are found out. The intersection point of satellite trajectory is obtained by regression analysis and discrete point crossover algorithm, and the corresponding calibration is carried out. Secondly, several interpolation algorithms are used to calculate the effective wave height, ocean wind speed and sea level height at each intersection, and the optimal difference method is obtained by analyzing and comparing the results of different difference methods. Finally, the ionospheric delay error is analyzed according to the data provided by the Marine Environment Forecast Center of the State Oceanic Administration, and several known ionospheric models are compared with their own dual-frequency correction effects. The results show that the GIM model has the best correction effect. It is suggested that GIM model should be used where the effect of dual frequency correction is not satisfactory. In addition, this paper uses the filtering principle of time series analysis to dedryness the effective wave height to get the waveform data with high signal-to-noise ratio, which can be used to analyze the interaction error between pulse signal and sea surface, that is, electromagnetic deviation. The error of ionospheric delay is mainly due to the refraction of electromagnetic signal propagation in the ionosphere. The influence of ionosphere can be reduced by using dual-frequency (Ku band and C-band) measurement mode. Bayesian statistical theory is used to deal with the mean variance of the altimetry noise in these two bands (Ku band and C band), so that the error of ionospheric delay can be reduced to less than cm. At the same time, the above-mentioned methods are used to process the Tp and JASON-1,2 series of satellite data, and the results obtained are compared with those of the HY-2A satellite data processing. It is convenient to find the error source and then reduce the error and analyze the merits and demerits of the model. The error analysis and calibration of ocean radar altimetry data plays an important role in the application of altimetry data. With the continuous improvement of HY-2A satellite data processing technology, the corresponding error analysis should be improved accordingly. Furthermore, the accuracy of altimetry is improved and the scientific application value of satellite data is improved.
【学位授予单位】：河南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P715.6
[Abstract]:Satellite radar altimeter (Satellite radar altimeter) is an important tool for real-time ocean monitoring. So far, many countries around the world have launched satellites carrying radar altimeter. Space-borne radar altimeter with all-weather altimeter? Full-time and global detection capability to monitor and observe the marine environment at all times, and to obtain a variety of marine dynamic environmental parameters, including effective wave height, wind speed, sea surface temperature, and so on. It also directly provides real-time monitoring data for early warning and forecasting of disastrous sea conditions. It also provides authoritative support for marine environmental protection, marine resources development, marine disaster prevention and mitigation, marine scientific research and national defense construction. Based on these factors, China also launched the HY-2 satellite in 2011. Through the deep study of the working principle of the HY-2 satellite, we have a deep understanding of the possible errors in the altimeter height measurement of the spaceborne radar. Based on the data provided by the Marine Environment Forecast Center of the State Oceanic Administration, the factors of echo waveform and the delay error of ionosphere signal during altimetry and their correction are analyzed and studied in this paper. Firstly, in order to calculate the sea level height, the echo waveforms of spaceborne radar altimeter are tracked and analyzed according to the existing models, and various factors affecting the echo waveforms are found out. The intersection point of satellite trajectory is obtained by regression analysis and discrete point crossover algorithm, and the corresponding calibration is carried out. Secondly, several interpolation algorithms are used to calculate the effective wave height, ocean wind speed and sea level height at each intersection, and the optimal difference method is obtained by analyzing and comparing the results of different difference methods. Finally, the ionospheric delay error is analyzed according to the data provided by the Marine Environment Forecast Center of the State Oceanic Administration, and several known ionospheric models are compared with their own dual-frequency correction effects. The results show that the GIM model has the best correction effect. It is suggested that GIM model should be used where the effect of dual frequency correction is not satisfactory. In addition, this paper uses the filtering principle of time series analysis to dedryness the effective wave height to get the waveform data with high signal-to-noise ratio, which can be used to analyze the interaction error between pulse signal and sea surface, that is, electromagnetic deviation. The error of ionospheric delay is mainly due to the refraction of electromagnetic signal propagation in the ionosphere. The influence of ionosphere can be reduced by using dual-frequency (Ku band and C-band) measurement mode. Bayesian statistical theory is used to deal with the mean variance of the altimetry noise in these two bands (Ku band and C band), so that the error of ionospheric delay can be reduced to less than cm. At the same time, the above-mentioned methods are used to process the Tp and JASON-1,2 series of satellite data, and the results obtained are compared with those of the HY-2A satellite data processing. It is convenient to find the error source and then reduce the error and analyze the merits and demerits of the model. The error analysis and calibration of ocean radar altimetry data plays an important role in the application of altimetry data. With the continuous improvement of HY-2A satellite data processing technology, the corresponding error analysis should be improved accordingly. Furthermore, the accuracy of altimetry is improved and the scientific application value of satellite data is improved.
【学位授予单位】：河南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P715.6
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