Abstract
The northeastern parts of China, including Beijing city, the capital of China, were hit by an intense dust storm on 15 April 2015. The present paper discusses aerosol and meteorological parameters associated with this dust storm event. The back trajectory clearly shows that the dust originated from Inner Mongolia, the border of China, and Mongolia regions. Pronounced changes in aerosol and meteorological parameters along the dust track were observed. High aerosol optical depth (AOD) with low Ångström exponent (AE) are characteristics of coarse-mode dominated dust particles in the wavelength range 440–870 nm during the dusty day. During dust storm, dominance of coarse aerosol concentrations is observed in the aerosol size distribution (ASD). The single scattering albedo (SSA) retrieved from AERONET station shows increase with higher wavelength on the dusty day, and is found to be higher compared to the days prior to and after the dust event, supported with high values of the real part and decrease in the imaginary part of the refractive index (RI). With regard to meteorological parameters, during the dusty day, CO volume mixing ratio (COVMR) is observed to decrease, from the surface up to mid-altitude, compared with the non-dusty days due to strong winds. O3 volume mixing ratio (O3VMR) enhances at the increasing altitudes (at the low-pressure levels), and decreases near the surface at the pressure levels 500–925 hPa during the dust event, compared with the non-dusty periods. An increase in the H2O mass mixing ratio (H2OMMR) is observed during dusty periods at the higher altitudes equivalent to the pressure levels 500 and 700 hPa. The mid-altitude relative humidity (RH) is observed to decrease at the pressure levels 700 and 925 hPa during sand storm days. With the onset of the dust storm event, the RH reduces at the surface level.
Highlights
Dust storms are common in many countries in the Northern Hemisphere almost every year
The minimum value of AE occurred on the dusty day, with an average value of 0.43, much lower compared to 1.02 observed on non-dusty days; such low values reflect a high ratio of coarse aerosol particles to small aerosol particles
With Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) total attenuated backscatter and depolarization ratio, airborne dusts are clearly observed over Mongolia regions
Summary
Dust storms are common in many countries in the Northern Hemisphere almost every year. Using eight ground-based observations from CSHNET, Xin et al [25] have analyzed the aerosol optical properties during the strong dust event of 16–21 April 2005, and found the mean value of AOD increased from 0.37 to 0.69, and AE decreased from 1.35 to 1.07 at sites in Beijing city. Numerous studies were carried out to study long range transport, physical, chemical, and optical properties of dust, as well as its influence on meteorological parameters using ground and satellite observations [2,3,34,35,36,37,38,39,40,41,42,43,44,45] These studies have provided a good understanding of the effect of dust storm on air quality, the global biogeochemical cycle, and environmental change. For the first time, we made efforts to use air quality data from ground network stations, AERONET, and multisatellites (MODIS, AIRS, CALIOP) to study characteristics and differences of aerosol, air quality, and atmospheric and meteorological parameters on the dusty day and non-dusty days
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