Tropical cyclone (TC) rainfall asymmetry is often influenced by vertical wind shear and storm motion. This study examined the effects of environmental vertical wind shear (200-850 hPa) and storm motion on TC rainfall asymmetry over the North Indian Ocean (NIO): the Bay of Bengal (BoB) and the Arabian Sea (AS). Four TC groups were used in this study: Cyclonic Storm (CS), Severe Cyclonic Storm (SCS), Very Severe Cyclonic Storm (VSCS) and Extreme Severe Cyclonic Storm (ESCS). The Fourier coefficients for wave number-1 was used to analyze the structure of TC rainfall asymmetry. Results show that the maximum TC rainfall asymmetry was predominantly in the downshear left quadrant in the BoB, while it placed to downshear right quadrant in the AS, likely due to the different primary circulation strength of the TC vortex. For the most intense cyclone (ESCS), the maximum TC rainfall asymmetry was in the upshear left quadrant in the BoB, whereas it was downshear right quadrant in the AS. It is evident for both basins that the magnitude of TC rainfall asymmetry declined (increased) with TC intensity (shear strength). This study also examined the collective effects of vertical wind shear and storm motion on TC rainfall asymmetry. Here, the analysis in case of the strong shear environment (>7 m s^-1) omitted for the AS because the maximum value for this basin was about 7 m s^-1. The result showed that the downshear left quadrant was dominant in the BoB for the maximum TC rainfall asymmetry. In a weak shear environment (<5 m s^-1), on the other hand, downshear right quadrant is evident for the maximum TC rainfall asymmetry in the BoB, while it placed dominantly downshear left quadrant in the AS. In the case of motion-relative wavenumber-1, the maximum TC rainfall asymmetry was dominantly downshear for both basins.

热带气旋（TC）的降雨不对称性通常受垂直风切变和风暴运动的影响。这项研究研究了北印度洋（NIO）：孟加拉湾（BoB）和阿拉伯海（AS）上的环境垂直风切变（200-850 hPa）和风暴运动对TC降雨不对称的影响。这项研究使用了四个TC组：气旋风暴（CS），严重气旋风暴（SCS），非常严重气旋风暴（VSCS）和极端严重气旋风暴（ESCS）。1号波的傅立叶系数用于分析TC降雨不对称的结构。结果表明，最大的TC降雨不对称主要集中在BoB的下剪切左象限，而在AS的下剪切右象限则位于最大，这可能是由于TC涡旋的一次循环强度不同所致。对于最强的气旋（ESCS），在BoB中，最大的TC降雨不对称性在上切变左象限，而在AS中则最大。对于这两个盆地来说，很明显，TC降雨不对称的幅度随着TC强度（抗剪强度）而降低（增加）。这项研究还研究了垂直风切变和风暴运动对TC降雨不对称性的集体影响。此处，在强剪切环境（> 7 ms^-1）对于AS省略了，因为该流域的最大值约为7 ms ^-1。结果表明，在最大的TC降雨不对称情况下，BoB的下降剪切左象限占主导地位。另一方面，在弱剪切环境（<5 ms ^-1）中，对于BoB中最大的TC降雨不对称性，右后象限明显为下剪切右象限，而在AS中则主要位于下剪切左象限。在相对运动波数为1的情况下，两个盆地的最大TC降雨不对称性主要是下降剪切。