Estimate of Boundary-Layer Height Using Aerosol Lidar and Laser Ceilometer during 2016-2017 Winter in Nanjing City, China

The Planetary boundary-layer height (PBLH) is investigated using observations from an aerosol lidar and a laser ceilometer in the north of Nanjing city, China from 28 December 2016 through 3 January 2017, when the atmosphere condition was translating from clear to polluted. The PBLHs are calculated with various algorithms and their temporal variations are obtained using the data collected. Investigation on the aerosol lidar observations shows that the gradient method (GM) and cubic root gradient method (CRGM) generate lower PBLHs comparing with those from logarithm gradient method (LGM) and normalized gradient method (NGM). Further, GM tends to underestimate PBLHs, while LGM and NGM are inclined to overestimate PBLHs on polluted days. CRGM, which is considered as the most reliable algorithm, presents PBLHs ranging from 172 m to 1575 m during the observation period. On the other hand, analysis on the laser ceilometer observations results the gradient method (BSG), standard deviation method (STD) and wavelet transform analysis (Haar) generate similar PBLHs with each other and have a maximum of 1490 m in these days. The PBLHs calculated by the two data sources and various algorithms all show obvious diurnal variation during either clean or polluted days, but the PBLHs are significantly lower in polluted days than those in clear days.