ABSTRACT

This work focused on the rain-induced characteristics of synthetic aperture radar (SAR) at the C- and X-bands. Six SAR images were collected in tropical cyclones: four C-band dual-polarized Sentinel-1 (S-1) images during the 2016 hurricane season and two vertical–vertical) polarized TerraSAR-X (TS-X) images of Hurricane Sandy (2012). Wind speeds were retrieved from the S-1 images at the vertical–horizontal polarization channel, and winds from the TS-X images were obtained from the Hurricane Research Division of the National Oceanic and Atmospheric Administration . Simultaneously, Tropical Rainfall Measuring Mission (TRMM) rain rates, current data from the HYbrid Coordinate Ocean Model and wave spectra simulated by the WAVEWATCH-III (WW3) model were collocated. The three-scale backscattering model was employed to simulate the normalized radar cross-section (NRCS)without considering the rain effect, yielding a 2.21-dB root mean square errorand 2.23-dB for S-1 and TS-X, respectively. The difference between model-simulated and observed NRCS was analysed using the TRMM rain rate. The results indicate a linear relationship of the difference at the X-band with the TRMM rain rate, while the difference at the C-band exhibited a ‘V’ relationship with the TRMM rain rate. It was also discovered that the difference at the X-band decreased with increasing wind speed, while the difference at the C-band increased with increasing wind speed.

摘要

这项工作的重点是在C波段和X波段由雨引起的合成孔径雷达（SAR）的特性。在热带气旋中收集了六张SAR图像：2016年飓风季节的四张C波段双极化Sentinel-1（S-1）图像，以及飓风桑迪（S-X）的两张垂直-垂直）极化TerraSAR-X（TS-X）图像。 2012）。从垂直-水平极化通道的S-1图像中检索出风速，从TS-X图像中获得的风来自美国国家海洋与大气管理局飓风研究部。同时，将热带降雨测量任务（TRMM）降雨率，来自混合坐标海洋模型的当前数据和由WAVEWATCH-III（WW3）模型模拟​​的波谱并置。在不考虑降雨影响的情况下，采用三尺度后向散射模型模拟归一化雷达横截面（NRCS），S-1和TS-X的均方根误差为2.21 dB，TS-X的均方根误差为2.23 dB。使用TRMM降雨率分析了模型模拟和观察到的NRCS之间的差异。结果表明，X波段的差值与TRMM雨率呈线性关系，而C波段的差值与TRMM雨率呈“ V”关系。还发现，随着风速的增加，X波段的差异减小，而随着风速的增加，C波段的差异增大。使用TRMM降雨率分析了模型模拟和观察到的NRCS之间的差异。结果表明，X波段的差值与TRMM雨率呈线性关系，而C波段的差值与TRMM雨率呈“ V”关系。还发现，随着风速的增加，X波段的差异减小，而随着风速的增加，C波段的差异增大。使用TRMM降雨率分析了模型模拟和观察到的NRCS之间的差异。结果表明，X波段的差值与TRMM雨率呈线性关系，而C波段的差值与TRMM雨率呈“ V”关系。还发现，随着风速的增加，X波段的差异减小，而随着风速的增加，C波段的差异增大。