The evolution of planetary boundary layer (PBL) was investigated using observations from a laser ceilometer, an eddy covariance system, and an automatic meteorological station in the north of Nanjing city during an air pollution episode in 2016–2017 winter. Based on 7-day observation under clean to polluted day, we recorded the temporal variations of backscatter signals observed by the ceilometer, and then intercompared the planetary boundary layer height (PBLH) retrieved from individual methods. The results show that backscatter signal gradient, standard deviation, and wavelet transform analysis methods generated similar PBLH values and PBL diurnal variation patterns. Moreover, the PBL structure varied diurnally, with distinct patterns corresponding to clean and polluted days. Based on these measurements, the relationships between PBLH, weather conditions, and contaminants were analyzed. Results show that on clean days, strong surface turbulence exchange makes the PBL fully developed and makes the PBLH increase sharply after sunrise, with a maximum of 1,483 m; on polluted days, stable synoptic conditions and the weaker wind speeds facilitated the accumulation of air pollutants, leading to smaller net surface radiation and weaker turbulence. Consequently, these conditions during polluted days led to lower PBLH values, which were typically less than 900 m.
Bibliographical noteFunding Information:
1Climate and Weather Disasters Collaborative Innovation Center, Key Laboratory for Aerosol‐Cloud‐Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing, China, 2Department of Earth and Environmental Sciences, Columbia University, New York, NY, USA, 3Department of Atmospheric Sciences, Yonsei University, Seoul, South Korea, 4State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
The National Key Research and Development Program of Ministry of Science and Technology of China (2016YFC0203304), and National Natural Science Foundation of China (4187050111, 41275022, 41711530223, and 41805080) supported this study. Fourth author was supported by the National Research Foundation of Korea grant funded by the Korean govern ment (MSIT) (NRF‐2018R1A5A 1024958). The data of daily Air Quality Index (AQI) and the concentration of particulate matter from the Nanjing Environmental Monitoring Station were downloaded from China National Environmental Monitoring Centre at https://www.cnemc.cn/sssj/. The 6‐ hourly NCEP/NCAR reanalysis data were download from The National Center for Atmospheric Research web service portal (https://rda.ucar.edu/ datasets/ds090.0/).Our thanks go to anonymous reviewers to improve our study.
All Science Journal Classification (ASJC) codes
- Aquatic Science
- Water Science and Technology
- Soil Science
- Geochemistry and Petrology
- Earth-Surface Processes
- Atmospheric Science
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science