| dc.description.abstract | The Chung-Li VHF radar station observed the 3-meter filed aligned irregularities of sporadic E on January 28,2008, February 5,2008, August 18,2008, February 26,2008, and March 1, 2009. We analyzed the mean Doppler velocity, spectral width, maximum SNR, zonal extent, thickness, mean height and trace velocity during the day time and night time, respectively. The conductivity at the daytime is higher than that at the nighttime, and as a result, the polarization of electric field is more liable to be cut off during the daytime. Therefore, the polarization of electric field at the nighttime is increased than that at the daytime, which, in turn, gradient of electron density is increased and irregularities produce a greater vibration. Further, based on our data, mean Doppler velocity, trace velocity, and maximal SNR detected at the nighttime are all increased compared with those obtained at the daytime, as anticipated. By means of the range of spectral width, we demonstrated that the irregularities observed at the Chung-Li VHF radar station is of 3-meter irregularities. In addition, our data indicated that the thickness of layer- typed irregularities at the daytime is increased than that at the nighttime; whereas zonal extent at the daytime is narrowed than that at the nighttime. The mean height is located around 96-99km. The mean height of layer -typed irregularities detected at the nighttime is slightly increased than that at the daytime. Notably, there are two peaks which is separated at the height of 102km. Further, the descending rate of the irregularities is increased when at the higher height compared with that at the lower height. Finally, by means of mean Doppler velocity distributed at the various height, we can estimate the character of wind- shear slope which demonstrated that the magnitude of wind-shear slope is largely in parallel with spectral width and SNR
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