We present a relatively simple method to estimate tropical cyclone (TC) surface wind structure (34-, 50-, and 64-kt wind radii) and intensity [maximum wind speed (MWS)] from wind fields acquired from the L -band SMAP radiometer and C -band Sentinel-1A/B and RADARSAT-2 synthetic aperture radar (SAR) between 2015 and 2020. The radiometer and SAR-derived wind radii and MWS are systematically compared with the best-track estimates. The root-mean-square errors (RMSEs) of R34, R50, and R64 are 31.2, 21.8, and 17.0 nmi (1 nmi = 1.852 km) for radiometer, and 21.7, 16.5, and 16.3 nmi for SAR, respectively. These error values are smaller than the averaged best-track uncertainty estimates for the three wind radii. Compared with the best-track reports, the bias and RMSE for the MWS estimates are −0.2 m/s and 5.8 m/s for radiometer, and 4.4 m/s and 9.1 m/s for SAR, respectively. These results are for the wind speeds in the range of 17–80 m/s. For the two typical TCs (Lionrock and Noru) in the Northwest Pacific Ocean, our results show that a combination of the radiometer and SAR wind data acquired within a very short time interval has the potential to simultaneously obtain reasonable measurements of the wind radii and intensity parameters. Moreover, for a TC with a long lifecycle, such as Typhoon Noru, we demonstrate that the high-resolution and multitemporal synergistic observations from SAR and radiometer are valuable for studying fine-scale features of the wind field and characteristics of wind asymmetry associated with intensity change, as well as the evolution of TC surface wind structure and intensity.

中文翻译：

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利用星载辐射计和合成孔径雷达估算热带气旋的风结构和强度

我们提出了一种相对简单的方法来估计热带气旋（TC）地表风的结构（34、50和64kt的风半径）和强度（最大风速（MWS）），这些风场来自于 大号 波段SMAP辐射计和 C -2015年至2020年之间的Sentinel-1A / B波段和RADARSAT-2合成孔径雷达（SAR）。将辐射计和SAR得出的风半径和MWS与最佳轨道估算值进行了系统比较。对于辐射计，R34，R50和R64的均方根误差（RMSE）为31.2、21.8和17.0 nmi（1 nmi = 1.852 km），对于SAR分别为21.7、16.5和16.3 nmi。这些误差值小于三个风半径的平均最佳航迹不确定性估计值。与最佳跟踪报告相比，MWS估计值的偏差和RMSE辐射计分别为-0.2 m / s和5.8 m / s，SAR分别为4.4 m / s和9.1 m / s。这些结果是针对17-80 m / s范围内的风速。对于西北太平洋的两个典型TC（Lionrock和Noru），我们的结果表明，在很短的时间间隔内获得的辐射计和SAR风数据的组合有可能同时获得风半径和强度参数的合理测量值。此外，对于寿命长的TC（例如台风Noru），我们证明了SAR和辐射计的高分辨率和多时相协同观测对于研究风场的精细尺度特征以及与强度相关的风不对称特征非常有价值。变化，以及TC地面风的结构和强度的演变。