首页 >  2009, Vol. 13, Issue (2) : 190-196

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10.11834/jrs.20090236

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一种消除全极化微波辐射计顺/逆风向遥感模糊性的新方案——星上定标和扫描机制设计的有关考虑
中国科学院空间科学与应用研究中心,北京,100190
摘要:

从观测方式的角度出发,讨论消除全极化微波辐射计遥感风向(顺风/逆风)模糊性的具体实施方案,提出合理进行星上定标和对地观测的设计思想.在研究全极化辐射计星上外定标方法的基础上,依据消除海面风向反演模糊性的算法,提出一种采用侧视扫描的机制,设计了在星上实现全极化微波辐射计对同一面元进行前、后两次扫描的具体方案,给出了一种在扫描周期内合理分配观测方位角和定标单元的方法.模拟结果表明,采用这种机制可以有效消除全极化辐射计风向反演存在的顺/逆风180°模糊,使风向反演精度大大提高.同时,考虑到卫星上空间资源的限制,单侧扫描刈幅宽度还能够达到760km以上,能够满足在较短的时间内覆盖全球的时间分辨率的要求.

Removing upwind/downwind ambiguity of ocean wind direction by polarimetric microwave radiometer: scheme design on on-orbit calibration and scanning geometry
Abstract:

Polarimetricmicrowave radiometer, a new type of remote sensor, canmeasure notonly the first two Stokes parameters, butalso the third and the fourth Stokes parameter of ocean surface radiation. Thus it opens a new field of microwave remote sensing on wind vectors. There is wind direction ambiguity in actually retrieved oceanic wind field using fully polarimetric radiometerdata becausewind direction signals inTvandThare very small comparing with other geophysical parameters, whileT3andT4are basically two order smaller than those ofhorizontaland verticalpolarization,and meanwhile there are calibration errors in each Stokesparameters. In thispaper, wededicate to improve the calibration accuracy by designing a fully onboard calibratorand reasonably allocating time forcalibration and observation during one scan cycle. The theory of polarimetricmicrowave radiometer calibration is given and the actual considerations of the on board fully polarimetric calibration standard are demonstrated. An original idea of calibrating polarimetric radiometer on satellite is presented. The relation between scan mode and wind direction retrieval error is analyzed. A new scanning geometry to remove thesewind direction ambiguous solutions is devised andmodeled. Simulation results show this kind of scanning geometry can removewind direction ambiguity effectively. The accuracy ofwind direction retrieval can be improved to15°. On the otherhand, due to the limited space on satellite, the swath of a single side scan can reach above 760 kilometers.

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