HY-2机载雷达高度计近岸波形重构及验证
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摘要
随着卫星测高技术的不断发展和成熟,雷达高度计作为有效载荷,被搭载于多颗卫星上。特别是随着TOPEX/POSEIDON、Jason-1/2、ERS-1/2和ENVISAT等一系列高度计卫星的发射,雷达高度计数据被广泛的应用于诸多海洋学研究。但是,卫星雷达高度计的信号在近岸由于受陆地或岛屿的影响,观测数据和数据校正量没有大洋上精确,造成了卫星雷达高度计在近岸海域测量的大部分数据不可用。因此需要对近海岸海域卫星测高数据进行波形重构,以获取准确的有效波高和海面高度,提高观测数据的利用率。
海洋二号卫星(HY-2)是我国自行研制的第一颗海洋动力环境卫星,计划在2011年8月发射,雷达高度计是其主要载荷之一。本文的研究是在“HY-2卫星地面系统建设”项目的支撑下,开展对我国自行研制的HY-2卫星雷达高度计数据波形重构算法的研究,研究工作将应用于HY-2卫星雷达高度计波形数据的处理。
本文的具体研究内容包括:
1、对国外卫星雷达高度计数据处理流程和数据分级方法进行分析,在此基础上针对HY-2卫星雷达高度计数据的特点,给出了合适的处理步骤和数据的分级方法,本文将HY-2高度计数据分为了0级、1级和2级,并分别给出了1级和2级数据产品的制作流程;
2、研究了OCOG算法、最大似然法和基于阈值的波形重构算法,并在此基础上对HY-2卫星雷达高度计的波形重构算法进行研究。由于HY-2卫星暂未发射,本文采用HY-2机载高度计校飞数据进行波形重构研究。着重研究了波形重构算法中的热噪声去除、波形归一化、上升沿起始点确定、半功率点确定、跟踪补偿量计算等。在上述研究的基础上,利用校飞数据进行了有效波高的反演;
3、将波形重构后得到的雷达高度计观测高度与GPS同步测量高度进行了比对。比对结果显示雷达高度计观测高度与GPS同步测量高度变化趋势一致;经波形重构后得到的有效波高同现场浮标测量的有效波高和Jason-1卫星同步观测的有效波高进行比对,经误差分析得RMS均小于50cm。
本文的研究成果:
比对结果证明,本研究中所使用的波形重构算法得到了比较好的效果,是适合HY-2卫星雷达高度计的波形重构算法。
With the gradual maturation of satellite altimetry, satellite radar altimeter as a payload has been carried on many satellites. Satellite radar altimeters such as TOPEX/POSEIDON, Jason-1/2, ERS-1/2 and ENVISAT etc. have become important tools for the study of ocean dynamic environment. However due to the influences of the islands or land on radar altimeter signals in the coastal area, data acquisition and correction along the coast are not as accurate as that on the ocean. And this often leads to unusable inshore data. In order to obtain accurate sea surface height (SSH) and significant wave height (SWH) and to improve the usability of acquired data, it becomes necessary to reconstruct altimeter waveform.
The first Chinese ocean dynamic environment satellite, namely HY-2 (Haiyang-2 satellite), is scheduled to launch in July 2011. The radar altimeter is an important remote sensing instrument carried on the HY-2 satellite. This study is supported by the“construction of HY-2 ground application system”and is focused on the waveform reconstruction calculation method development based on the data from HY-2 radar altimeter. Results will be applied to the processing of waveform data from HY-2 radar altimeter.
The main works in this study are as following:
1、Determined the data processing and classification method of HY-2 satellite radar altimeter based on analyzing current foreign satellite radar altimeter data processing and classification. HY-2 satellite radar altimeter data are divided into level 0, level 1 and level 2. Data processing method and flowchart of level 1B and level 2 are introduced.
2、Several commonly used radar altimeter waveform reconstruction methods are put forward in this study. Discussed the reconstruction of HY-2 radar altimeter waveform based on the above study. Since HY-2 satellite has not been launched, data of HY-2 airborne altimeter waveform are used instead. In this study we focused on the main steps involved in HY-2 radar altimeter waveform reconstruction including thermal noise elimination, normalization, starting point of rising edge calculation, half power point calculation, tracking errors compensation and etc. Significant wave height was also retrieved in this study.
3、The synchronized GPS data are used to confirm the observation height which is calculated by reconstructed altimeter waveform data. Results showed that the observation height of the two groups had the same variation trend. When comparing the SWH calculated by reconstructed radar altimeter waveform data with spot buoy data and Jason-1 satellite data, the RMS was found to be less than 50cm.
The main results in this study are as following:
The two comparisons above indicate the HY-2 radar altimeter waveform reconstruction method discussed in this thesis fits the HY-2 radar altimeter and can give good results on observation height and SWH.
海洋二号卫星(HY-2)是我国自行研制的第一颗海洋动力环境卫星,计划在2011年8月发射,雷达高度计是其主要载荷之一。本文的研究是在“HY-2卫星地面系统建设”项目的支撑下,开展对我国自行研制的HY-2卫星雷达高度计数据波形重构算法的研究,研究工作将应用于HY-2卫星雷达高度计波形数据的处理。
本文的具体研究内容包括:
1、对国外卫星雷达高度计数据处理流程和数据分级方法进行分析,在此基础上针对HY-2卫星雷达高度计数据的特点,给出了合适的处理步骤和数据的分级方法,本文将HY-2高度计数据分为了0级、1级和2级,并分别给出了1级和2级数据产品的制作流程;
2、研究了OCOG算法、最大似然法和基于阈值的波形重构算法,并在此基础上对HY-2卫星雷达高度计的波形重构算法进行研究。由于HY-2卫星暂未发射,本文采用HY-2机载高度计校飞数据进行波形重构研究。着重研究了波形重构算法中的热噪声去除、波形归一化、上升沿起始点确定、半功率点确定、跟踪补偿量计算等。在上述研究的基础上,利用校飞数据进行了有效波高的反演;
3、将波形重构后得到的雷达高度计观测高度与GPS同步测量高度进行了比对。比对结果显示雷达高度计观测高度与GPS同步测量高度变化趋势一致;经波形重构后得到的有效波高同现场浮标测量的有效波高和Jason-1卫星同步观测的有效波高进行比对,经误差分析得RMS均小于50cm。
本文的研究成果:
比对结果证明,本研究中所使用的波形重构算法得到了比较好的效果,是适合HY-2卫星雷达高度计的波形重构算法。
With the gradual maturation of satellite altimetry, satellite radar altimeter as a payload has been carried on many satellites. Satellite radar altimeters such as TOPEX/POSEIDON, Jason-1/2, ERS-1/2 and ENVISAT etc. have become important tools for the study of ocean dynamic environment. However due to the influences of the islands or land on radar altimeter signals in the coastal area, data acquisition and correction along the coast are not as accurate as that on the ocean. And this often leads to unusable inshore data. In order to obtain accurate sea surface height (SSH) and significant wave height (SWH) and to improve the usability of acquired data, it becomes necessary to reconstruct altimeter waveform.
The first Chinese ocean dynamic environment satellite, namely HY-2 (Haiyang-2 satellite), is scheduled to launch in July 2011. The radar altimeter is an important remote sensing instrument carried on the HY-2 satellite. This study is supported by the“construction of HY-2 ground application system”and is focused on the waveform reconstruction calculation method development based on the data from HY-2 radar altimeter. Results will be applied to the processing of waveform data from HY-2 radar altimeter.
The main works in this study are as following:
1、Determined the data processing and classification method of HY-2 satellite radar altimeter based on analyzing current foreign satellite radar altimeter data processing and classification. HY-2 satellite radar altimeter data are divided into level 0, level 1 and level 2. Data processing method and flowchart of level 1B and level 2 are introduced.
2、Several commonly used radar altimeter waveform reconstruction methods are put forward in this study. Discussed the reconstruction of HY-2 radar altimeter waveform based on the above study. Since HY-2 satellite has not been launched, data of HY-2 airborne altimeter waveform are used instead. In this study we focused on the main steps involved in HY-2 radar altimeter waveform reconstruction including thermal noise elimination, normalization, starting point of rising edge calculation, half power point calculation, tracking errors compensation and etc. Significant wave height was also retrieved in this study.
3、The synchronized GPS data are used to confirm the observation height which is calculated by reconstructed altimeter waveform data. Results showed that the observation height of the two groups had the same variation trend. When comparing the SWH calculated by reconstructed radar altimeter waveform data with spot buoy data and Jason-1 satellite data, the RMS was found to be less than 50cm.
The main results in this study are as following:
The two comparisons above indicate the HY-2 radar altimeter waveform reconstruction method discussed in this thesis fits the HY-2 radar altimeter and can give good results on observation height and SWH.
引文
[1] Phalippou L, Thouvenot E, Escudier P, er al. 25 years of altimeter developments at Alcatel Alenia Space. Venice, Italy: 2006.
[2] Stanley, H.R. The Geos-3 project, J. Geophys. Res., 1979(84), 3779-3783
[3] Tapley, B.D, Born, G.H, and Parke. The Seasat Altimeter and its Accuracy Assessment, J. Geophys. Res., 1982b(87), 3179-3188
[4] Bernstein, et al. SEASAT altimeter determination of ocean current variability, J. Geophys. Res., 1982(87): 3261-3268
[5] Lame, D.B., and Born, G.H. Seasat measurement system evaluation: achievements and limitations, J. Geophys. Res., 1982(87), 3175-3178
[6] Cheney, R.E., J.G. Marsh, and B.D. Beckley. Global mesoscale variability from collinear tracks of Seasat altimeter data, J. Geophys. Res., 1983(88), 4343-4354
[7] Fu, L.L. On the wave number spectrum of oceanic mesoscale variability observed by the Seasat altimetry, J. Geophys. Res., 1983(88), 4331-4341
[8] Timothy, J. U. the Integration and Application of Multi-Satellite Radar Altimetry [D], 2000.14
[9] Timothy, J. U. the Integration and Application of Multi-Satellite Radar Altimetry [D], 2000.15
[10] Fu, L.L., Christensen, C.A. et al., TOPEX/Poseidon mission overview, J. Geophys. Res.,1994(99), 24369-24381
[11]郭伟,张俊荣,张升伟,机载海洋雷达高度计工作模式及数据处理.遥感技术与应用,1995,10(4):25~36.
[12]许可,于志强,李茂堂,刘和光,中分辨率机载海洋雷达高度计信号处理方法及其实现.遥感学报,1997,l(2):101~106
[13] Brown G S. The Average Impulse Response of A Rough Sea Surface and Its Applications [J]. IEEE Trans Antannas Propag, 1977,A P225: 67274.
[14] Hayne G S.,Radar altimeter mean return waveforms from near-normal-incidence Ocean surface scattering, IEEE Trans. Antennas Propagat., 1980, AP-28: 687-692.
[15]徐莹,HY-2卫星高度计有效波高反演算法研究,硕士论文,2009
[16]王广运,王海瑛,卫星测高原理,科学出版社,1995.
[17] Etkins,R., and Epstein, E., The rise of global mean sea level as an indication of climate change,Science,vol.215,287-289,1982.
[18] Zwally, H.J., Bindschader, R.A.,Brenner,A.C.,Martin,T.V.,and Thomas,R.H., Surface elevation contours of Greenland and Antarctica ice sheets. J.Geophys.Res. 88, 1589-1596, 1983.
[19] Zwally, H.J., and Brenner,A.C.,Major, J.A.,Bindschadler,R.A.,and Marsh,J.G., Growth of Greenland ice sheet:Measurement,Science,vol.246,1587-1589,1989.
[20] Papa,F., Legresy,B., and Remy,F.,Use of the Topex-Poseidon dual-frequency radar altimeter over land surfaces, Remote Sensing of Environment, 87,136-147,2003.
[21] Legresy, B.,Papa,F., Remy,F.,et al.,ENVISAT radar altimeter measurements over continental surfaces and ice caps using the ICE-2 retracking algorithm, Remote Sensing of Environment,95,150-163,2005.
[22] Birkett,C.M.,The contribution of Topex/Poseidon to the global monitoring of climatically senstitive lakes, J.Geophys.Res.100,25,179-25,204, 1995
[23] Cazenave,A.,Bonnefond,P., and Dominh, K., Caspian sea level from Topex/Poseidon altimetry:Level now falling. Geophysical Research Letter, 24(8), 881-884,1997.
[24] Alsdorf,D.,Birkett,C.,Dunne,T.,Melack,J., and Hess,L., Water level changes in large Amazon Lake measured with spaceborn radar interferometry and altimetry, Geophysical Research Letter,28(14), 2671-2674,2001.
[25] Frappart, F.,S. Calmant, M.Cauhopé,F, Seyler and A.Cazenave, Preliminary results of ENVISAT RA-2-derived water levels validation over the Amazon basin, Remote Sensing of Environment, Volume 100(2), 252-264,2006.
[26] Mercier F. and Zanife O.Z.,Improvement of the Topex/Poseidon altimetric data processing for hydrological purposes(CASH project), Proc. of 15 years of progress in radar altimetry, Venice, Italy, 2006.
[27] Hancock, D. W.III, and D. W. Lockwood, Effects of Island in the Geosat Footprint, J. Geophys. Res., 95(C3), 2849-2855, 1990.
[28]鲍李峰,陆洋,许厚泽,浅海区域Topex/Poseidon测高卫星数据波形重构方法,地球物理学报, vol. 47, No.2,216-221,2004.
[29] A.Resti,J.Benveniste,M.Roca&G.Levrini,J.Johannessen,The Envisat Radar Altimeter System(RA-2),esa rbulletin 98 june 1999
[30] Moore R K and Williams C S.(1957).Radar terrain return at near-vertical incidence.Proc.IRE,45,220-238.
[31] Barrick, D.E., and Lipa, B. J., Analysis and interpretation of Altimeter Sea echo, Adv. Geophys.,1985,60-69
[32] Barrick D E. Remote sensing of sea state by radar, .IEEE OCEANS’72. 1972
[33] Wingham,D.J., Rapley, C.G. and Griffiths, H., New technique in satellite altimeter tracking systems,IGASS’86 Symposium Digest, Vol.1,185-190,1986.
[34] Bamber,J.L., Ice sheet alimeter processing scheme, International Journal of Remote Sensing, 15(4), 925-938, 1994.
[35]许可,姜景山,基于最大似然估计的雷达高度计跟踪处理,遥感技术与应用,第15卷,第2期,2000年6月
[36]常晓涛,李建成,郭金运等.一种多前缘多阈值的波形重构算法.地球物理学报, 2006 , 49 (6) :1629～1634
[37]李庆扬,王能超,易大义,数值分析[第四版],清华大学出版社,2001.90.
[38] Michael Anzenhofer, et al., Coastal altimetry and applications, 1999, 12, Report No.464:
[39]张有广,神舟四号高度计数据处理及功能评价,2004
[2] Stanley, H.R. The Geos-3 project, J. Geophys. Res., 1979(84), 3779-3783
[3] Tapley, B.D, Born, G.H, and Parke. The Seasat Altimeter and its Accuracy Assessment, J. Geophys. Res., 1982b(87), 3179-3188
[4] Bernstein, et al. SEASAT altimeter determination of ocean current variability, J. Geophys. Res., 1982(87): 3261-3268
[5] Lame, D.B., and Born, G.H. Seasat measurement system evaluation: achievements and limitations, J. Geophys. Res., 1982(87), 3175-3178
[6] Cheney, R.E., J.G. Marsh, and B.D. Beckley. Global mesoscale variability from collinear tracks of Seasat altimeter data, J. Geophys. Res., 1983(88), 4343-4354
[7] Fu, L.L. On the wave number spectrum of oceanic mesoscale variability observed by the Seasat altimetry, J. Geophys. Res., 1983(88), 4331-4341
[8] Timothy, J. U. the Integration and Application of Multi-Satellite Radar Altimetry [D], 2000.14
[9] Timothy, J. U. the Integration and Application of Multi-Satellite Radar Altimetry [D], 2000.15
[10] Fu, L.L., Christensen, C.A. et al., TOPEX/Poseidon mission overview, J. Geophys. Res.,1994(99), 24369-24381
[11]郭伟,张俊荣,张升伟,机载海洋雷达高度计工作模式及数据处理.遥感技术与应用,1995,10(4):25~36.
[12]许可,于志强,李茂堂,刘和光,中分辨率机载海洋雷达高度计信号处理方法及其实现.遥感学报,1997,l(2):101~106
[13] Brown G S. The Average Impulse Response of A Rough Sea Surface and Its Applications [J]. IEEE Trans Antannas Propag, 1977,A P225: 67274.
[14] Hayne G S.,Radar altimeter mean return waveforms from near-normal-incidence Ocean surface scattering, IEEE Trans. Antennas Propagat., 1980, AP-28: 687-692.
[15]徐莹,HY-2卫星高度计有效波高反演算法研究,硕士论文,2009
[16]王广运,王海瑛,卫星测高原理,科学出版社,1995.
[17] Etkins,R., and Epstein, E., The rise of global mean sea level as an indication of climate change,Science,vol.215,287-289,1982.
[18] Zwally, H.J., Bindschader, R.A.,Brenner,A.C.,Martin,T.V.,and Thomas,R.H., Surface elevation contours of Greenland and Antarctica ice sheets. J.Geophys.Res. 88, 1589-1596, 1983.
[19] Zwally, H.J., and Brenner,A.C.,Major, J.A.,Bindschadler,R.A.,and Marsh,J.G., Growth of Greenland ice sheet:Measurement,Science,vol.246,1587-1589,1989.
[20] Papa,F., Legresy,B., and Remy,F.,Use of the Topex-Poseidon dual-frequency radar altimeter over land surfaces, Remote Sensing of Environment, 87,136-147,2003.
[21] Legresy, B.,Papa,F., Remy,F.,et al.,ENVISAT radar altimeter measurements over continental surfaces and ice caps using the ICE-2 retracking algorithm, Remote Sensing of Environment,95,150-163,2005.
[22] Birkett,C.M.,The contribution of Topex/Poseidon to the global monitoring of climatically senstitive lakes, J.Geophys.Res.100,25,179-25,204, 1995
[23] Cazenave,A.,Bonnefond,P., and Dominh, K., Caspian sea level from Topex/Poseidon altimetry:Level now falling. Geophysical Research Letter, 24(8), 881-884,1997.
[24] Alsdorf,D.,Birkett,C.,Dunne,T.,Melack,J., and Hess,L., Water level changes in large Amazon Lake measured with spaceborn radar interferometry and altimetry, Geophysical Research Letter,28(14), 2671-2674,2001.
[25] Frappart, F.,S. Calmant, M.Cauhopé,F, Seyler and A.Cazenave, Preliminary results of ENVISAT RA-2-derived water levels validation over the Amazon basin, Remote Sensing of Environment, Volume 100(2), 252-264,2006.
[26] Mercier F. and Zanife O.Z.,Improvement of the Topex/Poseidon altimetric data processing for hydrological purposes(CASH project), Proc. of 15 years of progress in radar altimetry, Venice, Italy, 2006.
[27] Hancock, D. W.III, and D. W. Lockwood, Effects of Island in the Geosat Footprint, J. Geophys. Res., 95(C3), 2849-2855, 1990.
[28]鲍李峰,陆洋,许厚泽,浅海区域Topex/Poseidon测高卫星数据波形重构方法,地球物理学报, vol. 47, No.2,216-221,2004.
[29] A.Resti,J.Benveniste,M.Roca&G.Levrini,J.Johannessen,The Envisat Radar Altimeter System(RA-2),esa rbulletin 98 june 1999
[30] Moore R K and Williams C S.(1957).Radar terrain return at near-vertical incidence.Proc.IRE,45,220-238.
[31] Barrick, D.E., and Lipa, B. J., Analysis and interpretation of Altimeter Sea echo, Adv. Geophys.,1985,60-69
[32] Barrick D E. Remote sensing of sea state by radar, .IEEE OCEANS’72. 1972
[33] Wingham,D.J., Rapley, C.G. and Griffiths, H., New technique in satellite altimeter tracking systems,IGASS’86 Symposium Digest, Vol.1,185-190,1986.
[34] Bamber,J.L., Ice sheet alimeter processing scheme, International Journal of Remote Sensing, 15(4), 925-938, 1994.
[35]许可,姜景山,基于最大似然估计的雷达高度计跟踪处理,遥感技术与应用,第15卷,第2期,2000年6月
[36]常晓涛,李建成,郭金运等.一种多前缘多阈值的波形重构算法.地球物理学报, 2006 , 49 (6) :1629～1634
[37]李庆扬,王能超,易大义,数值分析[第四版],清华大学出版社,2001.90.
[38] Michael Anzenhofer, et al., Coastal altimetry and applications, 1999, 12, Report No.464:
[39]张有广,神舟四号高度计数据处理及功能评价,2004