Correlation Study of Planetary-Boundary-Layer-Height Retrievals from CL51 and CHM15K Ceilometers with Application To PM2.5 Dynamics in New York CityDingdong Li, Barry Gross, Yonghua Wu and Fred MosharyEPJ Web Conf., 237 (2020) 03010DOI: https://doi.org/10.1051/epjconf/202023703010