To provide theoretical guidance for the detection of ballistic missiles by skywave over-the-horizon radar, this paper first analyses the best way to detect ballistic missiles based on the rocket detection mechanism. Then using the diffusion model, chemical reaction model, and plasma diffusion model of neutral gas in the ionosphere, this paper studies the distribution of electrons and analyses the disturbance effect on the ionosphere caused by the release of ballistic missile exhaust plume in the ionosphere. Moreover, this paper considers the flight speed of the ballistic missile and the flow of the exhaust plume. Then the effects of different seasons, locations, and time zones on the release are compared. The results show that H2O can effectively dissipate background electrons to form spindle-shaped holes after release in the ionosphere. The height of the cavity radius corresponds to the peak of electron density of the background ionosphere, and the daytime dissipation is stronger than the nighttime dissipation, dissipation at low latitude is stronger than that at high latitude, and the seasonal difference is not obvious.

The South China coast has a high incidence of warm-sector heavy rainfall (WSHR) events. The ageostrophic winds in the boundary layer in most of these events associated with the southwesterly boundary layer jets (BLJs) mainly exhibit strong convergence at rainfall area. In this paper, we analyze two cases of WSHR in May 2013 and May 2015, which occurred in similar synoptic environments but varied in intensity, extent, and duration of rainfall, where the ageostrophic winds are the confrontational confluence and asymptotic confluence pattern, respectively. ERA-5 reanalysis data and the diagnostic equation of ageostrophic wind are used to examine the factors affecting the ageostrophic winds in the northern land region and the southern offshore region of the rainfall. The results suggest that land-sea contrast leads to the convergence of ageostrophic winds in the rainfall area. Boundary layer friction dominates the northeasterly ageostrophic winds on land. The diurnal variation of BLJs dominates the ageostrophic winds and their diurnal variation at sea, contributing southwesterly or southeasterly ageostrophic winds, so the phase difference between the land and sea forms confrontational or asymptotic confluence, respectively. BLJs with different intensities, extents, and diurnal variations can lead to different ageostrophic wind patterns and their confluence modes. The land-sea thermal contrast can directly affect ageostrophic winds, and it can also affect the diurnal variation of BLJs, thus affecting the ageostrophic winds and their confluence mode. It is further verified that the BLJs and thermal forcing are important in warm-sector heavy rainfall processes in South China.