The study deals with formative stages and lead detection time of tropical cyclogenesis using Okubo-Weiss Parameter, a proven robust eddy detection technique used for tropical cyclones that developed over the north Indian Ocean basin. Specifically, it aims to identify the initial traces of upper atmospheric genesis and understand the spatio-temporal evolution of pre-cyclonic eddy vortices in the atmospheric column using high-resolution WRF model outputs simulated for different cyclones. A coarser resolution grid of 27 km was used for identification purpose and a finer resolution of 9 km used to evaluate the characteristics of eddy vortices. Case studies were performed with four post-monsoon severe cyclones viz.; Phailin(2013), Vardah(2013), Gaja(2018), Madi(2013) and two pre-monsoon cyclones Mora(2017) and Aila(2009) that developed over this region. Study reveals a good skill in genesis prediction with a minimum of four days (~ 90 h) lead time in all cases irrespective of pre- and post-monsoon seasons. Factors that favor cyclogenesis during pre-monsoon season (except relative humidity) contribute to early detection of pre-cyclonic vortices in the atmosphere. Initiation mechanism of tropical cyclogenesis occurs at upper atmospheric levels and also detected at higher lead time for pre-monsoon cases unlike the post-monsoon cases. A lower relative vorticity at 850 hPa in pre-monsoon seasons is a major factor that initiates pre-cyclonic vortices at relatively higher levels compared to post-monsoon cyclones. Study also investigated the behavior of eddies in the atmospheric column for a non-developing case and compared these findings against developing cases. The study signifies that this technique is quite promising and has potential for early detection of tropical cyclogenesis in the atmospheric column prior to satellite detection over ocean surface.

这项研究使用Okubo-Weiss参数处理热带气旋形成的形成阶段和提前探测时间，Okubo-Weiss参数是一种经过验证的鲁棒涡流探测技术，用于北印度洋海盆上空发展的热带气旋。具体而言，其目的是使用针对不同气旋模拟的高分辨率WRF模型输出，识别高空大气成因的初始迹线，并了解大气柱中气旋前涡旋涡的时空演变。较粗的分辨率为27 km的网格用于识别目的，较细的分辨率为9 km的网格用于评估涡旋涡流的特性。案例研究是用四个季风后严重旋风进行的。Phailin（2013），Vardah（2013），Gaja（2018），Madi（2013）和两个季风前气旋Mora（2017）和Aila（2009）在这个地区发展起来的。研究表明，在任何情况下，与季风前后的季节无关，在所有情况下至少有四天（约90小时）的交货时间就能很好地预测成因。在季风前季节有利于气旋作用的因素（相对湿度除外）有助于大气中气旋前涡旋的早期检测。与季风后的情况不同，季风前的情况是热带气旋发生的起始机制发生在高层大气上，而且在较高的提前期也被发现。与季风后旋风相比，季风前季节在850 hPa较低的相对涡度是引发气旋前旋涡的主要因素。研究还调查了非开发案例中大气柱中涡流的行为，并将这些发现与开发案例进行了比较。