CryoSat-2 SARIn模式二级产品在内陆水域的偏差分析
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摘要
对比青藏高原及天山地区所有湖泊内CryoSat-2基线C版本二级产品(SIR_SIN_L2I)和ICESat测高结果发现,它们之间存在一个多达几十米的系统性偏差,这种偏差限制了多源测高数据的联合研究,必须加以消除。从一级数据出发,利用经典的重跟踪方法重新获得湖面高程,能很好地消除这个偏差。研究发现,当前的二级产品在生成过程中使用了错误的窗口延迟参数,从而导致该系统性偏差。因此,CryoSat-2的SARIn模式二级产品不能直接用于多源数据的联合分析,需要对一级数据重跟踪或直接在二级数据上加一个偏差改正。
We obtain lake elevations on the Tibetan plateau and Tianshan using CryoSat-2 baseline C level 2 products(SIR_SIN_L2 I) in SARIn mode and with ICESat level 2 products, finding a bias of tens of meters between them. The bias must be removed before joint analysis of multi-mission data. Using classic waveform retracking method, the new elevation measurements are obtained from CryoSat-2 L1 b products in SARIn mode. Results show that waveform retracking can remove the bias. We find that the bias is caused by a wrong window delay that is used during the production of the SARIn level 2 products. We conclude that current CryoSat-2 baseline C level 2 products in SARIn mode cannot be directly used in joint analysis of multi-mission data, and either waveform retracking or a bias correction should be added to level 2 products.
We obtain lake elevations on the Tibetan plateau and Tianshan using CryoSat-2 baseline C level 2 products(SIR_SIN_L2 I) in SARIn mode and with ICESat level 2 products, finding a bias of tens of meters between them. The bias must be removed before joint analysis of multi-mission data. Using classic waveform retracking method, the new elevation measurements are obtained from CryoSat-2 L1 b products in SARIn mode. Results show that waveform retracking can remove the bias. We find that the bias is caused by a wrong window delay that is used during the production of the SARIn level 2 products. We conclude that current CryoSat-2 baseline C level 2 products in SARIn mode cannot be directly used in joint analysis of multi-mission data, and either waveform retracking or a bias correction should be added to level 2 products.
引文
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[23] Mcmillan M,Corr H,Shepherd A,et al.Three-Dimensional Mapping by CryoSat-2 of Subglacial Lake Volume Changes[J].Geophysical Research Letters,2013,40(16):4 321-4 327
[2] Wang F,Bamber J L,Cheng X.Accuracy and Performance of CryoSat-2 SARIn Mode Data over Antarctica[J].IEEE Geoscience & Remote Sensing Letters,2015,12(7):1 516-1 520
[3] 褚永海,李建成,姜卫平,等.利用Jason-1数据监测呼伦湖水位变化[J].大地测量与地球动力学,2005,25(4):11-16(Chu Yonghai,Li Jiancheng,Jiang Weiping,et al.Monitoring of Water Level Variations of Hulun Lake with Jason-1 Altimetric Data[J].Journal of Geodesy and Geodynamics,2005,25(4):11-16)
[4] Song C Q,Ye Q H,Sheng Y W,et al.Combined ICESat and CryoSat-2 Altimetry for Accessing Water Level Dynamics of Tibetan Lakes over 2003-2014[J].Water,2015,7(9):4 685-4 700
[5] Jiang L G,Nielsen K,Andersen O B,et al.CryoSat-2 Radar Altimetry for Monitoring Freshwater Resources of China[J].Remote Sensing of Environment,2017,200:125-139
[6] Nielsen K,Stenseng L,Andersen O B,et al.The Performance and Potentials of the CryoSat-2 SAR and SARIn Modes for Lake Level Estimation[J].Water,2017,9(6):1-13
[7] Bouzinac C.CryoSat Product Handbook[Z].ESA,2015
[8] Jensen J R.Angle Measurement with a Phase Monopulse Radar Altimeter[J].IEEE Transactions on Antennas & Propagation,1999,47(4):715-724
[9] Fricker H A,Borsa A,Minster B,et al.Assessment of ICESat Performance at the Salar de Uyuni,Bolivia[J].Geophysical Research Letters,2005,32(21)
[10] Kurtz N T,Markus T,Cavalieri D J,et al.Comparison of ICESat Data with Airborne Laser Altimeter Measurements over Arctic Sea Ice[J].IEEE Transactions on Geoscience & Remote Sensing,2008,46(7):1 913-1 924
[11] 王莉,赵尚民.ICESat/GLA14最新数据与V33数据的对比[J].干旱区地理,2016,39(5):1 104-1 110(Wang Li,Zhao Shangmin.Comparsion of the Latest and V33 ICESat/GLA14[J].Arid Land Geography,2016,39(5):1 104-1 110)
[12] 郭金运,常晓涛,孙佳龙,等.卫星雷达测高波形重定及应用[M].北京:测绘出版社,2013(Guo Jinyun,Chang Xiaotao,Sun Jialong,et al.Waveform Retracking of Satellite Radar Altimeter and Applications[M].Beijing:Surveying and Mapping Press,2013)
[13] Wingham D J,Rapley C G,Griffiths H D.New Techniques in Satellite Altimeter Tracking Systems[C].IGARSS 86 Symposium,Zurich,1986
[14] Davis C H.A Robust Threshold Retracking Algorithm for Measuring Ice-Sheet Surface Elevation Change from Satellite Radar Altimeters[J].IEEE Transactions on Geoscience & Remote Sensing,1997,35(4):974-979
[15] Martin T V,Zwally H J,Brenner A C,et al.Analysis and Retracking of Continental Ice Sheet Radar Altimeter Waveforms[J].Journal of Geophysical Research:Oceans,1983,88(C3):1 608-1 616
[16] 孙佳龙.近海雷达卫星测高数据质量改善及在南海海潮模型中的应用研究[D].青岛:山东科技大学,2011(Sun Jialong.Study of Improving the Precision of Coast Satellite Altimetry and Application to South China Sea Tide Model[D].Qingdao:Shangdong University of Science and Technology,2011)
[17] Brown G S.The Average Impulse Response of A Rough Surface and Its Applications[J].IEEE Journal of Oceanic Engineering,1977,25(1):67-74
[18] Scagliola M,Fornari M.Main Evolutions and Expected Quality Improvements in Baseline C Level 1b Products[Z].2015
[19] Galilei V G.CryoSat Ice Data Quality Status Summary[Z].ESA,2017
[20] Urban T J.The Integration and Application of Multi-Satellite Radar Altimetry[J].Dissertation Abstracts International,2000
[21] Fricker H A,Padman L.Thirty Years of Elevation Change on Antarctic Peninsula Ice Shelves from Multimission Satellite Radar Altimetry[J].Journal of Geophysical Research:Oceans,2012,117(C2)
[22] Siegfried M R,Fricker H A,Roberts M,et al.A Decade of West Antarctic Subglacial Lake Interactions from Combined ICESat and CryoSat-2 Altimetry[J].Geophysical Research Letters,2014,41(3):891-898
[23] Mcmillan M,Corr H,Shepherd A,et al.Three-Dimensional Mapping by CryoSat-2 of Subglacial Lake Volume Changes[J].Geophysical Research Letters,2013,40(16):4 321-4 327