Technical note: Evolution of convective boundary layer height estimated by Ka-band continuous millimeter wave radar at Wuhan in central China

Abstract. Using the vertical velocity (VV) observed by a Ka-band millimeter wave cloud radar (MMCR) at Wuhan, we investigate the evolution of convective boundary layer height (CBLH) based on a specified threshold of VV variance. Compared with the CBLH retrieved from the lidar range corrected signal (RCS), the MMCR-derived CBLH exhibits lower values for a few hours post-sunrise and pre-sunset, but outside these two periods, they are generally in good agreement. Relative to the lidar RCS that is susceptible to the historical aerosol mixing processes, the CBLH estimated from the MMCR VV variance shows a rapid response to thick clouds and a less contamination by aerosol residual layer and long-distance transport of sand and dust, thus the MMCR VV observation can capture the CBLH evolution very well. The MMCR observation in 2020 depicts the seasonal and monthly variations in the CBLH. The seasonal mean CBLH reaches the peak heights of 1.29 km in summer, 1.14 km in spring, and 0.6 km in autumn and winter, with occurrence time between 13:30 and 15:00 LT. The maximum (mean) value of mean (daily maximum) CBLH rises steadily from 0.66 (0.87) km in January to 1.47 (1.76) km July, followed by a gradual decline to 0.42 (0.5) km in December. Statistical standard deviations are monthly-dependent, indicating the significant influence of weather conditions on the CBLH. This study improves our understanding of the Ka-band MMCR’s capability to monitor the CBLH, emphasizing its utility in tracking the dynamical processes in the boundary layer.