Calibration of the CryoSat-2 Interferometer and Measurement of Across-Track Ocean Slope
Calibration of the CryoSat-2 Interferometer and Measurement of Across-Track Ocean Slope
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DOI：
10.1109/tgrs.2012.2200298
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发表时间：
2011-12
影响因子：
8.2
通讯作者：
N. Galin;D. Wingham;R. Cullen;M. Fornari;Walter H. F. Smith;S. Abdalla
中科院分区：
文献类型：
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作者：
N. Galin;D. Wingham;R. Cullen;M. Fornari;Walter H. F. Smith;S. Abdalla
本文介绍了 CryoSat-2 干涉仪的校准，其主要目的是精确测量南极和格陵兰冰盖的高度。 2010 年 6 月至 9 月期间，在一系列卫星在 -0.6° 至 0.4° 之间滚动期间，从以“SARIN”模式运行的 SIRAL“A”雷达和冗余 SIRAL“B”雷达获得了热带和中纬度海洋上空的一系列 CryoSat-2 数据采集。利用回波相对于干涉仪基线的到达角、星跟踪器确定的卫星姿态以及 EGM08 大地水准面对海洋表面跨轨道坡度的估计，我们确定了干涉仪表面坡度估计中的误差作为滚转角和海洋表面波高的函数。发现这些与理论描述非常一致。角度干涉测量的比例因子确定为 0.973 ± 0.002。我们通过将此比例因子应用于测量的相位来估计干涉仪跨轨道坡度测量的精度。将该比例因子应用于测量时，获得了海洋大地水准面的跨迹斜率，其精度在 10 公里处为 26 μrad，在 1000 km 处为 10 μrad。我们得出的结论是，该仪器的性能大大超过了精确测定大陆冰盖倾斜表面高度所需的性能。结果还表明，CryoSat-2 提供了对海洋表面瞬时矢量梯度的首次观测，并且法向入射干涉仪配置在测量海洋跨轨道坡度方面具有比之前认识到的更大的潜力。
This paper describes the calibration of the CryoSat-2 interferometer, whose principal purpose is to accurately measure the height of the Antarctic and Greenland ice sheets. A sequence of CryoSat-2 data acquisitions over the tropical and midlatitude oceans were obtained between June and September 2010, from the SIRAL “A” and redundant SIRAL “B” radars operating in their “SARIN” mode, during a sequence of satellite rolls between -0.6° and 0.4°. Using the arrival angle of the echo relative to the interferometer baseline, the attitude of the satellite determined by the star trackers, and estimates of the ocean surface across-track slope from the EGM08 geoid, we determined the errors in the interferometer estimate of surface slope as functions of the roll angle and ocean surface waveheight. These were found to be in close agreement with the theoretical description. The scale factor of the interferometric measurement of angle was determined to be 0.973 ± 0.002. We estimate the accuracy of the across-track slope measurement of the interferometer by applying this scale factor to the measured phase. In applying this scale factor to the measurements, the across-track slope of the marine geoid was obtained with an accuracy of 26 μrad at 10 km and 10 μrad at 1000 km. We conclude that the instrument performance considerably exceeds that needed for the accurate determination of height over the sloping surfaces of the continental ice sheets. The results also demonstrate that CryoSat-2 provides the first observations of the instantaneous vector gradient of the ocean surface, and that the normal-incidence interferometric configuration has a greater potential for the measurement of the ocean across-track slope than has been previously recognized.