No abstract

Abstract. Agricultural soil erosion, both mechanical and eolic, may impact cloud processes, as some aerosol particles are able to facilitate ice crystal formation. Given the large agricultural sector in Mexico, this study investigates the ice nucleating abilities of agricultural dust collected at different sites and generated in the laboratory. The immersion freezing mechanism of ice nucleation was simulated in the laboratory via the Universidad Nacional Autónoma de México (UNAM) microorifice uniform deposit impactor (MOUDI) droplet freezing technique (DFT), i.e., UNAM-MOUDI-DFT. The results show that agricultural dust from the Mexican territory promote ice formation in the temperature range from −11.8 to −34.5 ∘C, with ice nucleating particle (INP) concentrations between 0.11 and 41.8 L−1. Furthermore, aerosol samples generated in the laboratory are more efficient than those collected in the field, with T50 values (i.e., the temperature at which 50 % of the droplets freeze) higher by more than 2.9 ∘C. Mineralogical analysis indicated a high concentration of feldspars, i.e., K-feldspar and plagioclase (>40 %), in most of the aerosol and soil samples, with K-feldspar significantly correlated with the T50 of particles with aerodynamic diameters between 1.8 and 3.2 µm. Similarly, the organic carbon (OC) was correlated with the ice nucleation efficiency of aerosol samples from 3.2 to 5.6 and from 1.0 to 1.8 µm. Finally, a decrease in INP efficiency after heating the samples at 300 ∘C for 2 h indicates that the organic matter from agricultural soils plays a predominant role in the ice nucleating abilities of this type of aerosol sample.

<p>Organic aerosol (OA) from natural or anthropogenic origin can be directly emitted into the atmosphere (primary organic aerosols, POA) or formed by secondary processes via the oxidation of volatile organic compounds (VOC). However, the formation pathways and their chemical composition of these secondary organic aerosols (SOA), which may contribute up to 90% of the OA mass, are not well understood to date, which is problematic due to the relevance of SOA on climate. To address this issue, this study uses a tracer-based approach to identify and quantify the contribution of different anthropogenic/biogenic VOCs precursors to the SOA formation. To do so, we combine experiments in a large scale atmospheric simulations chamber, CESAM (which means Multiphase Atmospheric Experimental Simulation Chamber), and field measurements during the ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) campaign conducted in the Paris area in summer 2022. This approach provides both a mechanistic study of the oxidation of targeted VOCs in simulated and controlled rural/urban atmospheres and the identification of targeted tracers in the real atmosphere, to quantify their concentrations in ambient air.</p> <p>The ACROSS dataset consists in atmospheric samples of submicron aerosols collected twice a day (day and night) in the urban area of Paris and the Rambouillet forest on the south-west of Paris, as well as samples collected onboard the Safire ATR-42 research aircraft on low-level flights targeting the  evolution and dilution of the Paris urban plume. The CESAM chamber dataset consists in samples of SOA generated by the OH oxidation of toluene/ m-xylene in various conditions.</p> <p>Filters are analyzed to provide with the chemical composition at the molecular scale by SFE-GC-MS (Supercritical Fluid Extraction Gas Chromatography- Mass Spectrometry) and UPLC-QTOF-MS (Ultra Performance Liquid Chromatography Time of Flight Mass Spectrometry). The organic mass and chemical speciation are obtained by aerosol mass spectrometry and the organic carbon (OC) concentrations by thermal-optical analysis.</p> <p>The first results of the ambient samples of Paris revealed that the OC concentration varied between 0.69 ± 0.07 and 9.48 ± 0.51 µgC/m<sup>3</sup>, which correspond to the 28% and 53% of the total mass of the submicron aerosols, for background and polluted (fire) conditions, respectively. These diverse conditions are favorable to trace the compounds identified during the simulation chamber experiments, such as benzoic acid, succinic acid, and 2-methyl-4-nitrophenol. These attempts will be presented and discussed in order to determine the contribution of specific precursors to SOA formation.</p>

<p>Atmospheric aerosols make significant contributions to several atmospheric chemical and physical processes. Aerosols from anthropogenic emissions have negative impact on air quality and human health. In recent years, significant progress has been made in understanding the anthropogenic pollutants. However, it is still not clear how mixtures of anthropogenic and biogenic emissions impact the regional climate and human health. To better understand aerosol physicochemical properties within the Paris urban plume when mixed with biogenic emissions, a comprehensive airborne measurement platform was deployed in the Île-de-France region in summer 2022 as part of the ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) campaign. In this study, the vertical and spatial distributions of aerosol chemical composition, size distributions, and optical properties during urban plume aging are characterized based on couples of in-situ measurement techniques like aerosol mass spectrometer (c-ToF-AMS), Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) and AVIRAD staged onboard the Safire ATR 42 research aircraft. Gas phase components are also detailed characterized by Proton-transfer-reaction mass spectrometry (PTR-ToF-MS) to act as tracers of anthropogenic and biogenic emissions. Based on gas and particulate phase organic information provided by laser-induced fluorescence technique (TDLIF), the production rate of particulate organic nitrate (pON) can also be estimated. These detailed airborne measurements of aerosol properties provide data that can contribute to modelling studies of aerosol characteristics.</p>

<p>Diversity in teams improves the quality of scientific research and fosters innovation (Plaut, 2010). In particular, since climate change is a global equity issue, its research demands diverse perspectives. For progress in the understanding of the Earth System, diversity of both scientists and study locations is important. Repeatedly, the geosciences have been shown to be among the least diverse research fields, in which women and other underrepresented groups are exposed to systemic biases (Simarski, 1992; Stokes et al., 2015; Bernard and Cooperdock, 2018). However, assessment of subdisciplines is lacking.</p><p>In this project we conduct the first analysis of diversity, equity, and inclusion (DEI) in the cloud physics community. We combine a metadata analysis of 7064 cloud physics papers which were published between 1970 and 2020 with a survey of ~200 participants from the cloud physics community.<br>The published papers analysis shows that female first author contributions become evident only after 1995. Today, only ca. 17% of studies in the cloud physics field are led by women. However, the relative retention rate for women equals that of men for both entering the field at the same time period. When we asked the participants if they felt included in the cloud physics community, it was encouraging to see that roughly 70% indicated that they felt always or most of the time included, but 30% felt excluded or only included some of the time. This was especially true for young people (<40; 35%), women (37%) and LGBTIQ+ (44%). 33% of those who identified as Asian, Hispanic, Latinx or Black also felt excluded or only included some of the time. Further, of the 200 participants surveyed, 23% identified as part of a minority group. Almost half of those reported that their minority status had a negative impact on their scientific career, particularly in terms of collaborations, promotions, publishing, funding, salary, and citations.<br>Geographically, authors from the Global North dominate, with less than 5% of studies led by authors with a tropical affiliation. Even where the location of a field study is tropical, the participation of local tropical authors is low, indicating widespread practice of the so-called helicopter or parachute science. However, while there is a consensus among respondents that collaborations with colleagues from tropical latitudes will advance the community, a large fraction of survey respondents are not planning such collaborations .</p><p>The data, results, and perspectives from this work can aid the cloud physics community to become aware of its DEI state, as well as to develop new strategies to improve itself and ultimately achieve a better understanding of the climate system.</p><p> </p><p><br>Bernard, R. E., and E. H. G. Cooperdock. “No Progress on Diversity in 40 Years.” Nature Geoscience (2018), https://doi.org/10.1038/s41561-018-0116-6.</p><p>Plaut, V. C. “Diversity Science: Who Needs It?” Psychological Inquiry (2010), https://doi.org/10.1080/1047840X.2010.492753.</p><p>Simarski, L. T. “Examining Sexism in the Geosciences.” Eos, Transactions American Geophysical Union (1992), https://doi.org/10.1029/91EO00210.</p><p>Stokes, P. J., R. Levine, and K. W. Flessa. “Choosing the Geoscience Major: Important Factors, Race/Ethnicity, and Gender.” Journal of Geoscience Education (2015), https://doi.org/10.5408/14-038.1.</p>

Abstract. Agricultural soil erosion, both mechanical and eolic, may impact cloud processes as some aerosol particles are able to facilitate ice crystals formation. Given the large agricultural sector in Mexico, this study investigates the ice nucleating abilities of agricultural dust collected at different sites and generated in the laboratory. The immersion freezing mechanism of ice nucleation was simulated in the laboratory via the Universidad Nacional Autónoma de México (UNAM)- Micro Orifice Uniform Deposit Impactor (MOUDI)-Droplet freezing technique (DFT) (UNAM-MOUDI-DFT). The results show that agricultural dust from the Mexican territory promote ice formation in a temperature range from −11.8 ºC to −34.5 ºC, with ice nucleating particle (INP) concentrations between 0.11 L−1 and 41.8 L−1. Furthermore, aerosol samples generated in the laboratory are more efficient than those collected in the field, with T50 values (i.e., the temperature at which 50 % of the droplets freeze) higher by more than 2.9 ºC. The mineralogical analysis indicated a high concentration of feldspars i.e., K-feldspar and plagioclase (> 40 %) in most of the aerosol and soil samples, with K-feldspar significantly correlated with the T50 of particles with sizes between 1.8 µm and 3.2 µm. Similarly, the organic carbon (OC) was correlated with the efficiency of aerosol samples from 3.2 µm to 5.6 µm and 1.0 µm to 1.8 µm. Finally, a decrease in the efficiency as INPs, after heating the samples at 300 ºC for 2 h, evidenced that the organic matter from agricultural soils can influence the role of INPs in mixed-phase clouds.

No abstract

No abstract