The waveform data of EnviSat satellite (28°N~32°N, 121°E~125°E) from October 2002 to May 2010 is processed by waveform retracking methodology based on waveform classification. The waveforms in this region are classified into ocean, pre-peak, post-peak, quasi-specular and complex waveforms, with percentages of 89.03%, 2.95%, 0.45%, 3.31% and 4.26%, respectively. For each waveform, correspondent waveform retracking methodology is used. Meanwhile, it is founded that there exist system biases between the sea surface heights(SSH) calculated by different waveform retracking methodologies and calculate optimum threshold level of OCOG, threshold and sub-waveform retracker, with 65%, 45% and 50% respectively. The results of waveform retracking show that the waveform retracking methodology based on waveform classification are prior to any single retracker, which could improve the precision of SSH from 16.62% to 53.86%. In addition, the crossover discrepancies are smaller after using waveform retracking. Specifically, the crossover discrepancies of pass 089 and pass 411 are declined from 1 m to 25 cm or so and the other crossover discrepancies are all around 2~6 cm.
[1] DENG X. Improvement of Geodetic Parameter Estimation in Coastal Regions from Satellite Radar Altimetry[D]. Perth: Curtin University of Technology, 2004.
[2] BROWN G S. The Average Impulse Response of a Surface and Its Applications[J]. IEEE Transactions on Antennas and Propagation, 1977, 25(1): 67-74.
[3] MARTIN T V, ZWALLY H J, BRENNER A C, et al. Analysis and Retracking of Continental Ice Sheet Radar Altimeter Waveform[J]. Journal of Geophysical Research, 1983, 88(C3): 1608-1616.
[4] DAVIS C H. A Robust Threshold Retracking Algorithm for Measuring Ice-sheet Surface Elevation Change from Satellite Radar Altimeters[J]. IEEE Transactions on Geoscience and Remote Sensing, 1997, 35(4): 974-979.
[5] HWANG C, GUO J Y, DENG X X, et al. Coastal Gravity Anomalies from Retracked GeoSat/GM Altimetry: Improvement, Limitation and the Role of Airborne Gravity Data[J]. Journal of Geodesy, 2006, 80(4): 204-216.
[6] LEE H, SHUM C K, YI Y C, et al. Laurentia Crustal Motion Observed Using TOPEX/Poseidon Radar Altimetry over Land[J]. Journal of Geodynamics, 2008, 46(3-5): 182-193.
[7] WINGHAM D J, RAPLEY C G, GRIFFITHS H. New Techniques in Satellite Tracking Systems[C]//Proceedings of IGARSS' 88 Symposium. [S.l.]: IEEE, 1988: 186-193.
[8] DENG X, FEATHERSTONE W E. A Coastal Retracking System for Satellite Radar Altimeter Waveforms: Application to ERS-2 Around Australia[J]. Journal of Geophysical Research, 2006, 111(C6), doi: 10.1029/2005JC003039.
[9] WANG Haihong, YUE Yingchun, ZOU Xiancai, et al. Classification of Radar Altimeter Waveforms Based on Cluster Analysis[J]. Geomatics and Information Science of Wuhan University, 2010, 35(7): 833-836. (汪海洪, 岳迎春, 邹贤才, 等. 基于聚类分析的卫星雷达测高波形分类研究[J]. 武汉大学学报: 信息科学版, 2012, 35(7): 833-836.)
[10] GOMMENGINGER C, THIBAUT P, FENOGLIO-MARC L, et al. Retracking Altimeter Waveforms Near the Coasts[M]//VIGNUDELLI S, KOSTIANOY A G, CIPOLLINI P, et al. Coastal Altimetry. Berlin: Springer-Verlag, 2011: 61-101.
[11] PENG Fukai, SHEN Yunzhong, ZHAO Jian. Analysis of Bias Characteristics in Different Waveform Retracking Methods of Satellite Altimetry[J]. Hydrographic Surveying and Charting, 2014, 34(3): 1-4. (彭福凯, 沈云中, 赵健. 卫星测高不同波形重构方法的偏差特性分析[J]. 海洋测绘, 2014, 34(3): 1-4.)
[12] BRENNER A C, KOBLINSKY C J, BECKLEY B D. A Preliminary Estimate of Geoid-induced Variations in Repeat Orbit Satellite Altimeter Observations[J]. Journal of Geophysical Research, 1990, 95(C3): 3033-3040.
[13] BROOMHEAD D S, KING G P. Extracting Qualitative Dynamics from Experimental Data[J]. Physica D: Nonlinear Phenomena, 1986, 20(2-3): 217-236.
[14] DONG Xiaojun, HUANG Cheng. Monitoring Global Mean Sea Level Variation with TOPEX/Poseidon Altimetry[J]. Acta Geodaetica et Cartographica Sinica, 2000, 29(3): 266-272. (董晓军, 黄珹. 利用TOPEX/Poseidon卫星测高资料监测全球海平面变化[J]. 测绘学报, 2000, 29(3): 266-272.)
[15] GÓMEZ-ENRI J, CIPOLLINI P, GOMMENGINGER C, et al. Improving Coastal Altimeter Products by A New Retracking Approach[C]//Remote Sensing of the Ocean, Sea Ice, and Large Water Regions 2009. Berlin: SPIE, 2009: 1-15.
[16] GÓMEZ-ENRI J, VIGNUDELLI S, QUARTLY G D, et al. Modeling EnviSat RA-2 Waveforms in the Coastal Zone: Case Study of Calm Water Contamination[J]. IEEE Geoscience and Remote Sensing Letters, 2010, 7(3): 474-478.
[17] GUO Jinyun, GAO Yonggang, CHANG Xiaotao, et al. Optimal Threshold Algorithm of EnviSat Waveform Retracking over Coastal Sea[J]. Chinese Journal of Geophysics, 2010, 53(4): 807-814. (郭金运, 高永刚, 常晓涛, 等. 近岸海域EnviSat卫星测高波形重定的Threshold 化法算法[J]. 地球物理学报, 2010, 53(4): 807-814.)
[18] HASSANI H. Singular Spectrum Analysis: Methodology and Comparison[J]. Journal of Data Science, 2007, 5(2): 239-257.
[19] IDRIS N H, DENG X. The Retracking Technique on Multi-peak and Quasi-specular Waveforms for Jason-1 and Jason-2 Missions near the Coast[J]. Marine Geodesy, 2012, 35(S1): 217-237.
[20] JIANG Weiping. The Application of Satellite Altimetry in Geodesy[D]. Wuhan: Wuhan University, 2000. (姜卫平. 卫星测高技术在大地测量学中的应用[D]. 武汉: 武汉大学, 2000.)
[21] TSENG K H, SHUM C K, YI Y C, et al. EnviSat Altimetry Radar Waveform Retracking of Quasi-specular Echoes over the Ice-covered Qinghai Lake[J]. Terrestrial, Atmospheric and Oceanic Sciences, 2013, 24(4): 615-627.
[22] LEE H, SHUM C K, EMERY W, et al. Validation of Jason-2 Altimeter Data by Waveform Retracking over California Coastal Ocean[J]. Marine Geodesy, 2010, 33(S1): 304-316.
[23] NEREM R S. Measuring Global Mean Sea Level Variations Using TOPEX/Poseidon Altimeter Data[J]. Journal of Geophysical Research, 1995, 100(C12): 25135-25151.
[24] KNUDSEN P, BROVELLI M. Collinear and Cross-over Adjustment of GeoSat ERM and Seasat Altimeter Data in the Mediterranean Sea[J]. Surveys in Geophysics, 1993, 14(4-5): 449-459.
[25] WANG Haihong, LUO Zhicai, YANG Yuande, et al. An Adaptive Retracking Method for Coastal Altimeter Data Based on Waveform Classification[J]. Acta Geodaetica et Cartographica Sinica, 2012, 41(5): 729-734. (汪海洪, 罗志才, 杨元德, 等. 基于波形分类的近海卫星测高数据自适应重跟踪方法[J]. 测绘学报, 2012, 41(5): 729-734.)
[26] WANG Huizan, ZHANG Ren, LIU Wei, et al. Improved Interpolation Method Based on Singular Spectrum Analysis Iteration and Its Application in Missing Data Recovery[J]. Applied Mathematics and Mechanics, 2008, 29(10): 1227-1236. (王辉赞, 张韧, 刘巍, 等. 奇异谱迭代插补的改进算法及其在缺损数据恢复中的应用[J]. 应用数学和力学, 2008, 29(10): 1227-1236.)
[27] YANG Yuande. The Determination of Marine Gravity Anomalies over Antarctic Oceans from Satellite Altimetry[D]. Wuhan: Wuhan University, 2010. (杨元德. 应用卫星测高技术确定南极海域重力场研究[D]. 武汉: 武汉大学, 2010.)
[28] ZHAO Jian, SHEN Yunzhong. Assessment of Retracked EnviSat Altimetry Sea Surface Heights Near Hainan Coastal Ocean[J]. Journal of Tongji University: Natural Science, 2013, 41(11): 1726-1731. (赵健, 沈云中. 海南近海EnviSat测高波形重构海面高质量评价[J]. 同济大学学报: 自然科学版, 2013, 41(11): 1726-1731.)
[29] ZHANG Chuanyin, GUO Chunxi, CHEN Junyong, et al. EGM2008 and Its Application in Chinese Mainland[J]. Acta Geodaetica et Cartographica Sinica, 2009, 38(4): 283-289. (章传银, 郭春喜, 陈俊勇, 等. EGM2008地球重力场模型在中国大陆的适用性分析[J]. 测绘学报, 2009, 38(4): 283-289.)
