Automatically tracing the Doppler velocities of clear-air and precipitation echoes in the VHF Doppler spectra was developed. It was workable for ~98 % of the radar data used, when a typhoon was passing through the radar site. The information of water types yielded by a dual-polarized microwave radiometer showed that strong updraft and turbulent atmosphere could bring the liquid water to the height above the melting layer, producing plenty of ice crystals and graupels in the upper troposphere.

This research makes an application of the multifrequency technique (RIM) to the spectral analysis (frequency domain) for both atmospheric and precipitation, especially for precipitation echoes. Various precipitation conditions such as stratiform and convective precipitations were investigated with RIM for the first time. The effectiveness and potential capabilities of RIM in resolving small-scale precipitation and atmosphere structures have been verified by conditional averaging analysis.

The multifrequency range imaging (RIM) capability of the Chung–Li VHF atmospheric radar is widely evaluated with long-term collected data. Effective corrections of range/time delay and range-weighting function effect for the radar echoes are achieved to improve the performance of RIM. The radar demonstrates its first successful observation of double-layer structures as well as their temporal and spatial variations with time. RIM results with and without significant precipitation are also shown.