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In Beijing, the probability of snowfall is decreasing as a result of global warming. At the same time, Beijing has suffered severe air pollution. In this paper, the concentration and particle size characteristics of BC (Black Carbon) in snow during the winter of 2015 in Beijing were analyzed by the SP2 method. The average concentration of BC in snow meltwater in Beijing is 82 ng/mL, with a minimum value of 62.9 ng/mL and a maximum of 210.6 ng/mL. The BC particle size in snow and ice in the Beijing area is mostly concentrated in the range of 70–400 nm. After log-normal, the BC particle size above 600 nm is still small, which should be closely related to the nature of the local BC emission source. The concentration of BC in snow is highly susceptible to meteorological conditions and local pollution levels. When Beijing is under the control of the east wind or the southeast wind, aerosols in the urban areas can easily accumulate in the northwestern mountains and then settle or participate in the snowfall process, resulting in an increase in BC aerosol accumulation in the snow, thus further changing the optical properties of snow in the Beijing area. [ABSTRACT FROM AUTHOR]

Liquid water content (LWC) in clouds determines the precipitable water of clouds, which is a crucial factor for aircraft safety and weather modification operations. More importantly, it influences the optical depth of clouds in the visible wavelength range, thus determining their climate cooling effects. Identifying and quantifying the LWC in mixed-phase clouds via remote sensing techniques remains challenging owing to the large variability of hydrometeor sizes in the cloud. In this study, we used in-situ aircraft measured full size distributions and collocated airborne radar reflectivity (Z) to explicitly fractionate the contributions of hydrometeors (cloud liquid droplets, ice, and precipitation particles) at different size ranges from the measured total Z. A linearly decreasing contribution of non-precipitation hydrometeors with increasing total Z was discovered for a range of cloud types, including cumulus, status, and deep convection clouds. The relationship between the mass and Z for each type of hydrometeor derived from in situ measurements was then applied. This approach of apportioning the contribution of cloud liquid droplets from the measured total Z as the first step significantly reduced the scattering of the correlation between the LWC and Z , as presented in previous studies; thus, the LWC was more accurately determined. The derived liquid water path exhibited high agreement with the microwave radiometer measurements. Our method of deriving the LWC from the total Z stemming from the in situ measured size distributions may be applied in other situations to derive the cloud liquid droplets, ice, and precipitation masses for clouds with a given radar Z. • Aircraft in-situ measured size distributions and collocated airborne radar reflectivity Z were used to derive cloud water. • Linearly decreased contribution of non-precipitation hydrometeors with increasing Z was found for various cloud types. • Apportioning the liquid water contribution from the measured total Z as the first step can more accurately determine LWC. [ABSTRACT FROM AUTHOR]