@article{petters_pujiastuti_satheesh_kasparoglu_sutherland_meskhidze_2024, title={Wind-driven emissions of coarse-mode particles in an urban environment}, volume={24}, ISSN={["1680-7324"]}, DOI={10.5194/acp-24-745-2024}, abstractNote={Abstract. Quantifying surface–atmosphere exchange rates of particles is important for understanding the role of suspended particulate matter in radiative transfer, clouds, precipitation, and climate change. Emissions of coarse-mode particles with a diameter greater than 0.5 µm provide giant cloud condensation nuclei and ice nuclei. These emissions are critical for understanding the evolution of cloud microphysical properties yet remain poorly understood. Here we introduce a new method that uses lidar retrievals of the elastic backscatter and Doppler velocity to obtain surface number emissions of particles with a diameter greater than 0.53 µm. The technique is applied to study particle number fluxes over a 2-month period from 1 June to 10 August 2022 during the TRACER campaign at an urban site near Houston, TX, USA. We found that all the observed fluxes were positive (upwards), indicating particle emission from the surface. The fluxes followed a diurnal pattern and peaked near noon local time. Flux intensity varied through the 2 months with multi-day periods of strong fluxes and multi-day periods of weak fluxes. Emission particle number fluxes peaked near ∼ 100 cm−2 s−1. The daily averaged emission fluxes correlated with friction velocity and were anticorrelated with surface relative humidity. The emission flux can be parameterized as F= 3000 u*4, where u* is the friction velocity in m s−1 and the emission flux F is in cm−2 s−1. The u* dependence is consistent with emission from wind-driven erosion. Estimated values for the mass flux are in the lower range of literature values from non-urban sites. These results demonstrate that urban environments may play an important role in supplying coarse-mode particles to the boundary layer. We anticipate that quantification of these emissions will help constrain aerosol–cloud interaction models that use prognostic aerosol schemes. }, number={1}, journal={ATMOSPHERIC CHEMISTRY AND PHYSICS}, author={Petters, Markus D. and Pujiastuti, Tyas and Satheesh, Ajmal Rasheeda and Kasparoglu, Sabin and Sutherland, Bethany and Meskhidze, Nicholas}, year={2024}, month={Jan}, pages={745–762} } @article{mahant_iversen_kasparoglu_bilde_petters_2023, title={Direct measurement of the viscosity of ternary aerosol mixtures}, volume={2}, ISSN={["2634-3606"]}, url={https://doi.org/10.1039/D2EA00160H}, DOI={10.1039/d2ea00160h}, abstractNote={The optical properties of particles change with change in their phase state. The optical change was exploited in this study to measure the transition temperature of sucrose, citric acid, and tartaric acid mixtures.}, journal={ENVIRONMENTAL SCIENCE-ATMOSPHERES}, author={Mahant, Sunandan and Iversen, Emil Mark and Kasparoglu, Sabin and Bilde, Merete and Petters, Markus D.}, year={2023}, month={Feb} } @article{kasparoglu_islam_meskhidze_petters_2022, title={Characterization of a modified printed optical particle spectrometer for high-frequency and high-precision laboratory and field measurements}, volume={15}, ISSN={["1867-8548"]}, DOI={10.5194/amt-15-5007-2022}, abstractNote={Abstract. The printed optical particle spectrometer (POPS) is a lightweight, low-cost instrument for measurements of aerosol number concentrations and size distributions. This work reports on modifications of the Handix Scientific commercial version of the POPS to facilitate its use in multi-instrument aerosol sampling systems. The flow system is modified by replacing the internal pump with a needle valve and a vacuum pump. The instrument is integrated into closed-flow systems by routing the sheath flow from filtered inlet air. A high-precision multichannel analyzer (MCA) card is added to sample the analog pulse signal. The MCA card is polled at 10 Hz frequency using an external data acquisition system and improves upon the count-rate limitation associated with the POPS internal data acquisition system. The times required to change the concentration between 90 % and 10 % and vice versa for a step change in concentration were measured to be 0.17 and 0.41 s at a flow rate of 5 cm3 s−1. This yields a sampling frequency of ∼ 1–2 Hz, below which the amplitude of measured fluctuations is captured with > 70 % efficiency. The modified POPS was integrated into the dual tandem differential mobility analyzer system to explore the coalescence of dimer particles. Results show that the pulse-height response increases upon dimer coalescence. The magnitude of the increase is broadly consistent with the change in light-scattering amplitude predicted by the T-matrix method. It is anticipated that this modified version of the POPS will extend the utilization of the technique for a range of field and laboratory applications. }, number={17}, journal={ATMOSPHERIC MEASUREMENT TECHNIQUES}, author={Kasparoglu, Sabin and Islam, Mohammad Maksimul and Meskhidze, Nicholas and Petters, Markus D.}, year={2022}, month={Sep}, pages={5007–5018} } @article{kasparoglu_perkins_ziemann_demott_kreidenweis_finewax_deming_devault_petters_2022, title={Experimental Determination of the Relationship Between Organic Aerosol Viscosity and Ice Nucleation at Upper Free Tropospheric Conditions}, volume={127}, ISSN={["2169-8996"]}, DOI={10.1029/2021JD036296}, abstractNote={Abstract}, number={16}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES}, author={Kasparoglu, Sabin and Perkins, Russell and Ziemann, Paul J. and DeMott, Paul J. and Kreidenweis, Sonia M. and Finewax, Zachary and Deming, Benjamin L. and DeVault, Marla P. and Petters, Markus D.}, year={2022}, month={Aug} } @article{kasparoglu_wright_petters_2022, title={Open-hardware design and characterization of an electrostatic aerosol precipitator}, volume={11}, ISSN={["2468-0672"]}, DOI={10.1016/j.ohx.2022.e00266}, abstractNote={Electrostatic precipitators are devices that remove charged particles from an air stream. We present the design and characterization of an electrostatic precipitator that is intended to be incorporated into aerosol sampling equipment. Hardware and software components of the design are open, all components can be directly purchased from vendors, and the device can be assembled with standard tools. Generic components are used to allow the repurposing of parts for other uses. The computer-controlled high-voltage power supply box associated with the project can be used for other common high-voltage applications in Aerosol Science and Technology, such as data acquisition and control systems for scanning mobility particle sizers. Computational fluid dynamics simulations are used to quantify the 3D flow field. The transfer function associated with the partial transmission is characterized through modeling and experiments. The observed transfer function is unique but deviates from the ideal transfer function due to the distortion of the flow near the inlet and the outlet of the device. Singly charged particles up to 624 nm and 253 nm can be completely removed for 0.5 L min−1 and 1 L min−1, respectively. We anticipate that our device will increase the accessibility of the technique to a broader audience.}, journal={HARDWAREX}, author={Kasparoglu, Sabin and Wright, Timothy P. and Petters, Markus D.}, year={2022}, month={Apr} } @article{kasparoglu_li_shiraiwa_petters_2021, title={Toward closure between predicted and observed particle viscosity over a wide range of temperatures and relative humidity}, volume={21}, ISSN={["1680-7324"]}, DOI={10.5194/acp-21-1127-2021}, abstractNote={Abstract. Atmospheric aerosols can exist in amorphous semi-solid or glassy phase states whose viscosity varies with atmospheric temperature and relative humidity. The temperature and humidity dependence of viscosity has been hypothesized to be predictable from the combination of a water–organic binary mixing rule of the glass transition temperature, a glass-transition-temperature-scaled viscosity fragility parameterization, and a water uptake parameterization. This work presents a closure study between predicted and observed viscosity for sucrose and citric acid. Viscosity and glass transition temperature as a function of water content are compiled from literature data and used to constrain the fragility parameterization. New measurements characterizing viscosity of sub-100 nm particles using the dimer relaxation method are presented. These measurements extend the available data of temperature- and humidity-dependent viscosity to −28 ∘C. Predicted relationships agree well with observations at room temperature and with measured isopleths of constant viscosity at ∼107 Pa s at temperatures warmer than −28 ∘C. Discrepancies at colder temperatures are observed for sucrose particles. Simulations with the kinetic multi-layer model of gas–particle interactions suggest that the observed deviations at colder temperature for sucrose can be attributed to kinetic limitations associated with water uptake at the timescales of the dimer relaxation experiments. Using the available information, updated equilibrium phase-state diagrams (-80∘C