Abstract
To investigate the particulate characteristics of a haze episode, data from two ceilometers with wavelengths of 532 nm and 910 nm, respectively, were studied intensively. By combining the data from the ceilometers with data from a sounding balloon, an automatic meteorological station, and a Grimm 180 PM instrument, analyses of the haze process of a short haze event were performed. The results showed that the relatively calm weather conditions were favorable to the occurrence of the haze and that higher relative humidity had a great influence on visibility. The extinction profiles from the ceilometers reflected the existence of an inverted structure of the temperature profiles and demonstrated the extinction differences at two different wavelengths. Because extinction has a positive correlation with relative humidity, the effect of hygroscopic growth was analyzed at the two different wavelengths. As hygroscopic growth of the particles proceeded, the longer wavelength became more sensitive to the large particles, and vice versa. The hygroscopic growth factor and the Angstrom exponent showed a negative correlation, and the correlation coefficients at 532 nm and 910 nm were 0.54 and 0.86, respectively. The accumulation mode particles were more stable through time than the coarse mode particles, and the variation of the coarse mode particles coincided well with the variation of the Angstrom exponent from the two ceilometers.
Highlights
Haze is an important environmental issue worldwide and has received increasing attention due to its impacts on visibility, air quality, radiative forcing, regional climate, and human health
The China Meteorological Administration (CMA) defines haze as a condition in which atmospheric visibility is less than 10 km and relative humidity is less than 90% [1]
For the two different wavelengths, the particles showed different optical characteristics, and the longer wavelength was more sensitive to larger particles
Summary
Haze is an important environmental issue worldwide and has received increasing attention due to its impacts on visibility, air quality, radiative forcing, regional climate, and human health. Aerosols affect Earth’s radiation balance directly by scattering and absorbing solar shortwave and longwave radiation They act as condensation nuclei for clouds, thereby changing the clouds’ microphysical properties and life cycles, and affect the climate system indirectly [1,2]. The humidity had an important impact on visibility during the severe haze events, and the altitude variation of the Planetary Boundary Layer (PBL) determined the intensity of the haze [5]. Zhang used spaceborne and ground-based Lidar observations over the Jinhua Basin in the province of Zhejiang to analyze the aerosol vertical distribution during a haze event both temporally and spatially [6]. For the increased atmospheric particulates during a haze episode, the ceilometer can obtain a sufficient signal-to-noise ratio to invert the optical properties of the particulates. In this study, based on data from two ceilometers with two different wavelengths, more microphysical particulate characteristics of a haze were studied intensively
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
