A portable lidar system has been developed for monitoring the evolution of the atmospheric boundary layer (ABL) using aerosols as the tracers of atmospheric motion. This lidar system utilizes state-of-the-art technology with a high repetition rate, low pulse energy laser, and photon-counting detection. The system is capable of continuous, autonomous data acquisition in both daytime and nighttime. During daytime, the aerosol profiles measured with the lidar are found to have sufficient signal strength to observe the structure of the ABL, which plays an important role in air pollution phenomena. The time series of the range-squared signal has been used for the interpretation of the ABL dynamics.