Observation of tropical cyclones by high-resolution scatterometry
Observation of tropical cyclones by high-resolution scatterometry
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DOI：
10.1029/97jc01911
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发表时间：
1998-04-15
影响因子：
3.6
通讯作者：
Tournadre, J
中科院分区：
文献类型：
--
作者：
Quilfen, Y;Chapron, B;Tournadre, J
欧洲遥感卫星（ERS）C波段散射仪提供了热带气旋（TC）之后的表面风场的前所未有的视图。C波段的散射计测量能够穿透对流风暴云，观测地面风场，精度较高。然而，测量的分辨率（50 x50 km（2））限制了对此类中尺度事件中散射仪信号的解释。在几公里的尺度上存在的地面风的强梯度被平滑的测量功能，如风的强度和位置的最大值，和中心的位置。除了地球资源卫星系统之外，分别由喷气推进实验室和欧洲航天局设计的ADEOS和METOP卫星上的散射仪将能够以大约25 x25公里（2）的分辨率测量后向散射系数。制作了几组ERS-1轨道，对TC事件进行采样，实验分辨率为25 x25 km（2）。将分辨率提高2倍，可以比50公里分辨率更准确地定位TC中的风最大值和最小值。此外，更好的分辨率减少了占主导地位的辐射噪声的地球物理噪声（单元内风速的变化和雨的影响），从而提高了后向散射测量的清晰度。提出了在TC内获得的大风和高海况情况下的后向散射测量的全面分析，以改进对来自后向散射模型的风矢量的解释，该模型目前仅在中性条件下校准到中等风（< 20 m/s）。TOPEX-海神双频高度计的观测也用于这一目的。描述了热带气旋地面风的模式，并讨论了最大风场和辐散场的不对称性特征。
Unprecedented views of surface wind fields in tropical cyclones thereafter TCs) are provided by the European Remote Sensing Satellite (ERS) C band scatterometer. Scatterometer measurements at C band are able to penetrate convective storms clouds, observing the surface wind fields with good accuracy. However the resolution of the measurements (50x50 km(2)) limits the interpretation of the scatterometer signals in such mesoscale events. The strong gradients of the surface wind existing at scales of a few kms are smoothed in the measured features such as the intensity and location of the wind maxima, and the position of the center. Beyond the ERS systems, the scatterometers on-board the ADEOS and METOP satellites, designed by the Jet Propulsion Laboratory and by the European Space Agency, respectively, will be able to produce measurements of the backscattering coefficient at about 25x25 km(2) resolution. A few sets of ERS-1 orbits sampling TC events were produced with an experimental 25x25 km(2) resolution. Enhancing the resolution by a factor of 2 allows location of the wind maxima and minima in a TC with a much better accuracy than at 50 km resolution. In addition, a better resolution reduces the geophysical noise (variability of wind speed within the cell and effect of rain) that dominates the radiometric noise and hence improves the definition of the backscattering measurements. A comprehensive analysis of the backscattering measurements in the case of high winds and high sea states obtained within TCs is proposed in order to refine the interpretation of the wind vector derived from a backscattering model that is currently only calibrated up to moderate winds (< 20 m/s) in neutral conditions. Observations of the TOPEX-POSEIDON dual-frequency altimeter are also used for that purpose. Patterns of the surface winds in TCs are described and characteristic features concerning asymmetries in the maximum winds and in the divergence field are discussed.