High-resolution Beijing MST radar detection of tropopause structure and variability over Xianghe (39.75°tN, 116.96°tE), China

Abstract. As a result of partial specular reflection from the atmospheric stable layer, the radar tropopause (RT) can simply and directly be detected by VHF radars with vertical incidence. Here, the Beijing MST radar measurements are used to investigate the structure and the variabilities of the tropopause in Xianghe, China with a temporal resolution of 0.5 hour from November 2011 to May 2017. High-resolution radar-derived tropopause is compared with the thermal lapse-rate tropopause (LRT) that defined by the World Meteorological Organization (WMO) criterion from twice daily radiosonde soundings and with the dynamical potential vorticity tropopause (PVT) that defined as the height of 2 PVU surface. During all the seasons, the RT and the LRT in altitude agree well with each other with a correlation coefficient of ≥ 0.74. Statistically, weaker (higher) tropopause sharpness seems to contribute to larger (smaller) difference between the RT and the LRT in altitude. The RT agrees well with the PVT in altitude during winter and spring with a correlation coefficient of ≥ 0.72, while the correlation coefficient in summer is only 0.33. As expected, the monthly mean RT and LRT height both show seasonal variations. Lomb-Scargle periodograms show that the tropopause exhibits obvious diurnal variation throughout the seasons, whereas the semidiurnal oscillations are rare and occasionally observed during summer and later spring. Our study shows the good capability of the Beijing MST radar to determine the tropopause height, as well as present its diurnal oscillations.