Raindrop size distribution (DSD) observations during the passage of landfalling tropical cyclone Nivar by impact (JWD) and laser (LPM and PARSIVEL) disdrometers are used to unveil the DSD characteristics in the eyewall as well as the inner and outer rainbands. Disdrometer measurements collected at the same location are used to study the effect of wind, measuring principle, and hardware processing on the DSDs and, in turn, on estimated rain integral and polarimetric parameters. The concentration of raindrops of diameters between 0.7 and 1.5 mm increases with rain rate (R) in all the regions of Nivar, while the magnitude of the increase is higher in the eyewall than in the inner and outer rainbands. The DSD characteristics reveal that for a given R, relatively larger reflectivity (Z) and mass-weighted mean diameter (D_m) are found in the outer rainband, and smaller Z and D_m are found in the eyewall than in other regions of a tropical cyclone (TC). Raindrops of diameter 3 mm in size are observed frequently in inner and outer rainbands; however, they are infrequent in the eyewall at R greater than 5 mm h⁻¹. The DSDs and estimated rain integral and polarimetric parameters are distinctly different for various disdrometers at similar environmental conditions. Raindrops greater than 3 mm in size are infrequent in the JWD recordings, while they are frequent in the LPM and PARSIVEL, indicating that LPM and PARSIVEL overestimate the raindrop size when the fall path deviates from nadir due to horizontal wind. The wind effect on the recorded DSD as well as estimated rain integral and polarimetric parameters are not uniform in various regions of Nivar for different disdrometers as the measuring principle and hardware processing further influence these effects. Along with the differences in measured DSD spectra, the resonance effects at X band for raindrops greater than 3 mm cause variations in the estimated polarimetric parameters between the disdrometers.

中文翻译：

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热带气旋尼瓦尔通过期间的雨滴尺寸分布 (DSD)：测量原理和风对 DSD 的影响以及从冲击和激光测距仪检索的雨积分和偏振参数

热带气旋尼瓦尔登陆期间通过撞击 (JWD) 和激光（LPM 和 PARSIVEL）测距仪进行的雨滴大小分布 (DSD) 观测用于揭示眼壁以及内外雨带中的 DSD 特征。在同一位置收集的测距仪测量值用于研究风、测量原理和硬件处理对 DSD 的影响，进而研究估计的降雨积分和极化参数。直径在 0.7 和 1.5 毫米之间的雨滴浓度在尼瓦尔的所有区域都随着降雨率 ( R ) 的增加而增加，而眼壁的增加幅度高于内外雨带。DSD 特性表明，对于给定的R，相对较大的反射率（Z ) 和质量加权平均直径 ( D _m ) 存在于外雨带中，与热带气旋 (TC) 的其他区域相比，在眼壁中发现的Z和D _m更小。内雨带和外雨带经常观察到直径为 3 毫米的雨滴；然而，它们在R大于 5 mm h ^{−1的眼壁中很少见}. 对于类似环境条件下的各种测距仪，DSD 和估计的降雨积分和极化参数明显不同。大于 3 毫米的雨滴在 JWD 记录中很少见，而在 LPM 和 PARSIVEL 中却很常见，这表明当水平风导致下落路径偏离最低点时，LPM 和 PARSIVEL 高估了雨滴大小。风对记录的 DSD 的影响以及估计的降雨积分和极化参数在 Nivar 的不同地区对于不同的测距仪是不一致的，因为测量原理和硬件处理进一步影响这些影响。随着测量的 DSD 光谱的差异，X 波段对于大于 3 毫米的雨滴的共振效应会导致测角计之间估计的偏振参数发生变化。