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首页> 外文会议>CryoSat third user workshop >INLAND WATER SAR ALTIMETRY: NEW TECHNIQUES AND METHODS FOR THE HYDROLOGICAL E XPLOITATION OF CRYOSAT DATA
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INLAND WATER SAR ALTIMETRY: NEW TECHNIQUES AND METHODS FOR THE HYDROLOGICAL E XPLOITATION OF CRYOSAT DATA

机译：内陆水域测高：CRYOSAT数据水文电子化的新技术和方法

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摘要

The concept of SAR Altimetry has found so far itsrnimmediate application and interest among the usersrnprincipally over open ocean and coastal zone domains.rnBut a new applicative territory remains still basicallyrnunexplored: the inland water theme.rnIndeed, the SAR/SARin technology looks veryrnattractive for inland water users thanks to the resolutionrnshrinkage in along-track direction that will allow now tornmonitor more efficiently small water bodies and tornreduce the land contamination from the off-nadir landrntargets.rnFurther, with respect to the SAR mode, the SARinrnMode has the additional advantage of:rn1) a more robust on-board tracking lock systemrnand a four time longer receiving window thatrnenables the radar to follow better the very steeprntopographic reliefs without loss of tracking,rn2) the possibility to infer the echo origin’s anglernand distinguish between nadir and off-nadirrnreturn.rnThe current Delay/Doppler processing, that is actuallyrnapplied over open ocean, is suitable as well for inlandrnwater studies, provided that:rn1) a weighting function is applied in azimuthrnbefore the beam forming operation is executed,rnin order to limit the azimuth ambiguities orrn“ghosting” effect.rn2) an oversampling at least by factor 2 is appliedrnduring the range compression in order tornproperly sample the specular echoes.rnOn top of this, clearly a standard open ocean SAR Echornphysically-based model (like SAMOSA or CNES/CPPrnModel) is not always suitable for inland water studiesrnbecause of the very peaky waveforms from still waters.rnFor this scope, we developed a re-tracking scheme ablernto change and adapt the model’s waveform to specularrnwater conditions (still water) or diffusive waterrnconditions (rough water).rnIn SAR mode, thanks to the high instrumental PulsernRepetition Frequency and to an accurate Delay/DopplerrnProcessing, the real antenna beam-width (with an alongtrackrnfootprint of 16 km) can be split in a series ofrnSynthetic Doppler Beams, each one with a footprint ofrn300 meters.rnBecause these Doppler Beams are synthetic, they can bernsteered to any point of the overflown ground-track andrnhence virtually a SAR Altimeter has the potential tornprovide an altitude measurement at any desired surfacernlocation along the ground-track.rnBecause rivers and small lakes are very localizedrntargets, it seems sensible, in case of application of SARrnAltimetry over inland water domain, to steer all thernDoppler Beams exactly in the middle of the river/lake’srnwater body in order to get a water level measurementrnthe most clean and uncontaminated possible.rnA secondary option could be to over-sample thernriver/lake’s crossing, fixing surface locations along thernlake/river’s cross at a space distance lesser than 300rnmeters (the intrinsic CryoSat’s along track resolution) inrnorder to increase the number of available waterrnmeasurements at the lake/river’s cross.rnFor the first time, this concept will be attempted andrnimplemented for a series of selected rivers/lakes targets.rnThe current work is a feasibility study preparatory forrnthe data exploitation of the Sentinel-3 TopographyrnMission over inland water.
机译：到目前为止，SAR Altimetry的概念已经在用户中得到了迅速的应用和关注，特别是在开放的海洋和沿海地区。rn但是，仍然基本上没有开发出新的应用领域：内陆水域主题。实际上，SAR / SARin技术对于内陆水域非常有吸引力。用户得益于沿路径方向的收缩率rrnr收缩，这将使现在能够更有效地监测小型水体并减少低空登陆目标的土地污染。rn此外，相对于SAR模式，SARinrnMode具有以下额外优势：rn1 ）更加强大的机载跟踪锁定系统-以及更长的四倍接收窗口-使雷达能够更好地跟随非常陡峭的地形起伏而不会丢失跟踪，rn2）可以推断出回波起源的角度并区分天底和离天底回波。当前的延迟/多普勒处理，实际上是在远洋上应用，也适用于内陆水域研究，条件是：rn1）在执行波束形成操作之前对方位角应用加权函数，以限制方位角模糊度或“重影”效应。rn2）至少以2倍进行过采样在范围压缩过程中应用了波分反射，以便对镜面回波进行适当采样。在此之上，很明显，基于开放海域SAR物理模型的标准模型（如SAMOSA或CNES / CPPrn模型）并不总是适用于内陆水域研究，因为来自在此范围内，我们开发了一种重新跟踪方案，可以更改模型的波形并使之适应于镜面水条件（静止水）或扩散水条件（粗糙水）。在SAR模式下，由于仪器脉冲高，重复频率高并且精确的延迟/多普勒处理，可以将实际天线的波束宽度（沿轨迹的足迹为16 km）划分为一系列ams，每个足迹的测量距离为rn300米。由于这些多普勒波束是合成的，因此可以将其转向到溢出的地面轨道的任何点，因此SAR高度计实际上有可能在沿着地面轨道的任何所需表面位置提供高度测量。由于河流和小湖是非常局部的目标，因此，在内陆水域上应用SAR测高仪的情况下，将所有多普勒波束精确地引向河/湖水体的中部以获取水位测量值似乎是明智的。第二种选择是过分地测量河床/河道的交叉点，沿湖床/河道的交叉点固定表面位置，间距小于300毫米（固有的CryoSat沿轨道分辨率），以增加可用的数量。在湖/河两岸的水域测量。第一次，将尝试并实现这个概念为一系列选定的河流/湖泊目标而定。目前的工作是对Sentinel-3地形任务在内陆水域进行数据开发的可行性研究。

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  • 来源
    《CryoSat third user workshop》|2013年|1-7|共7页
  • 会议地点 Dresden(DE)
  • 作者

    Dinardo Salvatore; Nicolas Bercher; Bruno Manuel Lucas; Jér?me Benveniste;

  • 作者单位

    SERCO/ESRIN, Via Sciadonna 24/26, Frascati, Italy, Email: salvatore.dinardo@esa.int;

    LEGOS/CNRS, av. Edouard Belin,18, Toulouse, France, Email: nicolas.bercher@legos.obs-mip.fr;

    DEIMOS/ESRIN, Av. D. Jo?o II, Lote 1.17.01 - 10o, Lisbon, Portugal, Email: bruno.manuel.lucas@esa.int;

    ESA/ESRIN, Via Galileo Galilei, Frascati, Italy, Email: jerome.benveniste@esa.int;

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  • 正文语种 eng
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