Aerosol properties computed from aircraft-based observations during the ACE- Asia campaign

For a vertical profile with three distinct layers (marine boundary, pollution and dust), observed during the ACE-Asia campaign, we carried out a comparison between the modeled lidar ratio vertical profile and that obtained from collocated airborne NASA AATS-14 sunphotometer and shipborne Micro-Pulse Lidar (MPL) measurements. Vertically resolved lidar ratio was calculated from two size distribution vertical profiles - one obtained by inversion of sunphotometer-derived extinction spectra, and one measured in-situ - combined with the same refractive index model based on aerosol chemical composition. The aerosol model implies single scattering albedos of 0.78 - 0.81 and 0.93 - 0.96 at 0.523 microns (the wavelength of the lidar measurements), in the pollution and dust layers, respectively. The lidar ratios calculated from the two size distribution profiles have close values in the dust layer; they are however, significantly lower than the lidar ratios derived from combined lidar and sunphotometer measurements, most probably due to the use of a simple nonspherical model with a single particle shape in our calculations. In the pollution layer, the two size distribution profiles yield generally different lidar ratios. The retrieved size distributions yield a lidar ratio which is in better agreement with that derived from lidar/sunphotometer measurements in this layer, with still large differences at certain altitudes (the largest relative difference was 46%). We explain these differences by non-uniqueness of the result of the size distribution retrieval and lack of information on vertical variability of particle refractive index. Radiative transfer calculations for this profile showed significant atmospheric radiative forcing, which occurred mainly in the pollution layer. We demonstrate that if the extinction profile is known then information on the vertical structure of absorption and asymmetry parameter is not significant for estimating forcing at TOA and the surface, while it is of importance for estimating vertical profiles of radiative forcing and heating rates

Moss bag sensitivity for the assessment of airborne elements at suburban background site during spring/summer season characterized by Saharan dust intrusions

Moss transplants of Hypnum cupressiforme and Sphagnum girgensohnii were tested for efciency in detection of airborne element pollution at a suburban background site during short time exposure of 15 days (twelve consecutive periods) and during prolonged exposure from one to six months. Concomitantly, particulate matter (PM10, PM2.5) was sampled during three identifed Saharan dust episodes, while MERRA-2 data were used for estimation of dust concentration at ground level to which the moss bags were exposed during 15-day periods. The concentrations of 22 potentially toxic elements were measured in the moss and PM10 samples. The results showed that 15-day bag exposure at the background location could not provide a measurable and reliable signature of the elements in the moss transplants, except for Al, V, As, Ga, Y, and Tb, unlike the extended moss bag exposure of a couple of months. These were also the only elements whose concentrations were increased multifold in PM10 samples during the most intense dust episode, which was also recorded by S. girgensohnii bags exposed in the corresponding 15-day period. The ratio of crustal elements (Ca/Al, Mg/Al) in PM10 and moss samples (3-month exposed) was in line of those reported for dust transported from western Africa. The V/Al, Ga/Al, and Tb/Al concentration ratio values in PM10 and S. girgensohnii samples were higher for dust days contrary to the As/Al ratio, which could be used to distinguish between dust and fossil fuel combustion pollution sources. The moss bag technique could be used as a simple tool for tracking long-range transported elements, but after prolonged moss bag exposure (3 months)

Mineralogy sensitive immersion freezing parameterization in DREAM

Dust aerosols are abundant in the atmosphere and are very efficient ice nucleating particles at temperatures below −15°C. Depending on temperature, dust particles containing certain minerals (i.e., feldspar and quartz) are the most active as ice nuclei. A mineralogy-sensitive immersion freezing parameterization for ice nucleating particle concentration (INPC) is implemented in Dust Regional Atmospheric Model (DREAM) for the first time. Additionally, four mineralogy-indifferent parameterizations are implemented, two for immersion freezing and two for deposition nucleation. Dust concentration and its feldspar and quartz fractions are forecasted by DREAM for a dust episode in the Mediterranean in April 2016. DREAM results are compared with vertical profiles of cloud-relevant dust concentrations and INPC from ground-based lidar measurements in Potenza, Italy and Nicosia, Cyprus. INPC predictions are also compared with vertical profiles of ice crystal number concentration (ICNC) from satellite observations for two overpasses over the dust plume. The model successfully simulates the evolution and vertical extent of the dust plume. Mineralogy-sensitive and mineralogy-indifferent INPC parameterization results generally differ by about an order of magnitude. Forecasted INPC and observed ICNC values differ by an order of magnitude for all parameterizations. Feldspar fraction increase within a dust plume during transport can increase INPC by around 6% at −35°C, and up to 17% at −25°C, but sedimentation can reduce this effect. Over the Atlantic, mineralogy-sensitive parameterization predicts horizontal distribution of clouds with higher probability of success, while in the Mediterranean; the results for different parameterizations show lower variability.Authors LI, AJ, and MK acknowledge funding provided by the Institute of Physics Belgrade, through the grant by the Ministry of Education, Science, and Technological Development of the Republic of Serbia. EM is grateful to Dr. Jean Sciare for hosting the PollyXT-NOA lidar in the Cyprus institute during the INUIT-BACCHUS-ACTRIS experiment. We thank EARLINET (https://www.earlinet.org/, last access: 12 December 2020), ACTRIS (https://www.actris.eu, last access: 12 December 2020) and PollyNET (http://polly.tropos.de, last access: 15March 2021) for the data collection, calibration, processing and dissemination. We thank the PollyNet group for their support during the development and operation of the PollyXT-NOA lidar system. We are grateful to the AERIS/ICARE Data and Services Center for generating and storing the DARDAR products and for providing access to the CALIPSO data used and their computational center (http://www.icare.univ-lille1.fr/, last access: 8 August 2019). We thank the NASA CloudSat Project and NASA/LaRC/ASDC for making available the CloudSat and CALIPSO products, respectively, which are used to build the synergetic DARDAR products. We are grateful to Jann Schrod and Bingemer Heinz G. for the provision of UAV-FRIDGE measurement data. The NUIT-BACCHUS-ACTRIS experiment received support from the Deutsche Forschungsgemeinschaft (grant no. 1525, INUIT), the European Union’s Seventh Frame-work813 Program (grant no. 603445, BACCHUS), the European Union’s Horizon 2020 research and innovation program (654109,ACTRIS-2). EM was funded by the European Research Council (grant no. 725698, D-TECT) and by a DLR VO-R young investigator group and the Deutscher Akademischer Austauschdienst (grant no. 57370121).Peer ReviewedPostprint (author's final draft

Air quality in urban parking garages (PM10, major and trace elements, PAHs): Instrumental measurements vs. active moss biomonitoring

This study was performed in four parking garages in downtown of Belgrade with the aim to provide multi-pollutant assessment. Concentrations of 16 US EPA priority PAHs and Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sr and Zn were determined in PM10 samples. The carcinogenic health risk of employees' occupational exposure to heavy metals (Cd, Cr, Ni and Pb) and PAHs (B[a]A, Cry, B[b]F, B[k]F, B[a]P and DB[ah]A) was estimated. A possibility of using Sphagnum girgensohnii moss bags for monitoring of trace element air pollution in semi-enclosed spaces was evaluated as well. The results showed that concentrations of PM10, Cd, Ni and B[a]P exceeded the EU Directive target values. Concentration of Zn, Ba and Cu were two orders of magnitude higher than those measured at different urban sites in European cities. Cumulative cancer risk obtained for heavy metals and PAHs was 4.51 x 10(-5) and 3.75 x 10(-5) in M and PP, respectively; upper limit of the acceptable US EPA range is 10(-4). In the moss, higher post-exposure than pre-exposure (background) element concentrations was observed. In comparison with instrumental monitoring data, similar order of abundances of the most elements in PM10 and moss samples was found. However, using of the S. girgensohnii moss bag technique in indoor environments needs further justification. (C) 2013 Elsevier Ltd. All rights reserved