Tropical cyclones (or TCs) being one of the most extreme weather events, have the potential to cause catastrophic destruction to both human lives and properties. Its life span generally extends from a few days to weeks and the destruction caused by its combined effect of duration and size is incomparable to any other forms of atmospheric disturbances. Recent findings have suggested the rise in intensified TCs and their structural modulation in the global ocean basins like North Atlantic (NA) and Western North Pacific (WNP). Over the North Indian Ocean (NIO) basin, several observational and modeling studies have been carried out during the past three decades, which included the climatological aspects. However, the structural characteristics involving TC size, radial parameters, vertical structure, and associated environmental conditions have not been emphasized extensively. To address the said aspect, the thesis work emphasizes the estimation and distribution of TC size, radial parameters, and related meteorological factors, by using scatterometer observations, global analyses, IMD (India Meteorological Department), and JTWC (Joint Typhoon Warning Centre) best track records, besides other relevant data sets. Also, the study adopted the Weather Research and Forecasting (WRF) modeling system and the three-dimensional variational data assimilation technique through WRF-DA to understand the impact of scatterometer winds on structural characteristics. The study period is constrained to 2001-2020, based on the availability of the scatterometer data sets at the time of execution of the work. Accordingly, observational studies considered 71 TCs, whereas the modeling study considered 67 cases. Larger size TCs are observed near the higher latitude of the NIO region, and the size of systems increases with an increase in latitude. The size of the pre-monsoon season TCs is found to be larger in comparison to post-monsoon season systems over NIO. An empirical relationship is also established based on the linear regression method to determine the size of TCs using SCATSAT data. The results presented in this work indicate that scatterometer wind data with a spatial resolution of ~6 to 25 km would be handy enough to study the structural characteristics of NIO TCs. The possible causes of environmental factors influencing TC size are investigated. The model simulated results helped to enrich the knowledge regarding the radial characteristics as well as vertical structures of the TCs.