The Cyprus Institute

About: The Cyprus Institute is a other organization based out in Nicosia, Cyprus. It is known for research contribution in the topics: Aerosol & Environmental science. The organization has 418 authors who have published 1252 publications receiving 32586 citations.

Vertical profiles of tropospheric ozone from MAX-DOAS measurements during the CINDI-2 campaign: Part 1 - Development of a new retrieval algorithm

Abstract: Ground‐based measurements of tropospheric ozone (O3) are valuable for studies of atmospheric chemistry, air pollution, climate change, and for satellite validation. The Multi Axis Differential Optical Absorption Spectroscopy (MAX‐DOAS) technique has been widely used to derive vertical profiles of trace gases and aerosols in the troposphere. However, tropospheric O3 has not yet been satisfactorily derived from MAX‐DOAS measurements due to the influence of stratospheric O3 absorption. In this study, we developed two new retrieval approaches for tropospheric O3 from MAX‐DOAS measurements. In method 1, stratospheric O3 profiles from external data sources are considered in the retrieval. In method 2, stratospheric and tropospheric O3 are separated based on the temperature‐dependent differences between tropospheric and stratospheric O3 absorption structures in the UV spectral range. The feasibility of both methods is first verified by applying them to synthetic spectra. Then they are applied to real MAX‐DOAS measurements recorded during the CINDI‐2 campaign in Cabauw, the Netherlands (September 2016). The obtained results are compared with independent O3 measurements and global chemical transport model simulations. Good agreement of the near‐surface O3 concentrations with the independent data sets is found for both methods. However, tropospheric O3 profiles are only reasonably derived using method 1, while they are significantly overestimated at altitudes above 1 km using method 2, probably due to the approximation of the ring spectra used to correct the rotational Raman scattering structures in the DOAS fit. Advantages and disadvantages of both methods are discussed and improvement directions are suggested for further studies.

Overview: On the transport and transformation of pollutants in the outflow of major population centres – observational data from the EMeRGe European intensive operational period in summer 2017

Abstract: . EMeRGe ( E ffect of M egacities on the transport and transformation of pollutants on the R egional to G lobal scal e s) is an international project focusing on atmospheric chemistry, dynamics and transport of local and regional pollution originating in megacities and other major population centres (MPCs). Airborne measurements, taking advantage of the long range capabilities of the HALO research platform (High Altitude and Long range research aircraft, www.halo-spp.de ), are a central part of the research project. In order to provide an adequate set of measurements at different spatial scales, two field experiments were positioned in time and space to contrast situations when the photochemical transformation of plumes emerging from MPCs is large. These experiments were conducted in summer 2017 over Europe and in the inter-monsoon period over Asia in spring 2018. The intensive observational periods (IOP) involved HALO airborne measurements of ozone and its precursors, volatile organic compounds, aerosol particles and related species as well as coordinated ground-based ancillary observations at different sites. Perfluorocarbon (PFC) tracer releases and model forecasts supported the flight planning and the identification of pollution plumes. This paper describes the experimental deployment of the IOP in Europe, which comprised 7 HALO research flights with aircraft base in Oberpfaffenhofen (Germany) for a total of 53 flight hours. The MPC targets London (Great Britain), Benelux/Ruhr area (Belgium, The Netherlands, Luxembourg and Germany), Paris (France), Rome and Po Valley (Italy), Madrid and Barcelona (Spain) were investigated. An in-flight comparison of HALO with the collaborating UK-airborne platform FAAM took place to assure accuracy and comparability of the instrumentation on-board. Generally, significant enhancement of trace gases and aerosol particles are attributed to emissions originating in MPCs at distances of hundreds of kilometres from the sources. The proximity of different MPCs over Europe favours the mixing of plumes of different origin and level of processing and hampers the unambiguous attribution of the MPC sources. Similarly, urban plumes mix efficiently with natural sources as desert dust and with biomass burning emissions from vegetation and forest fires. This confirms the importance of wildland fire emissions in Europe and indicates an important but discontinuous contribution to the European emission budget that might be of relevance in the design of efficient mitigation strategies. The synergistic use and consistent interpretation of observational data sets of different spatial and temporal resolution (e.g. from ground-based networks, airborne campaigns, and satellite measurements) supported by modelling within EMeRGe, provides a unique insight to test the current understanding of MPC pollution outflows. The present work provides an overview of the most salient results and scientific questions in the European context, these being addressed in more detail within additional dedicated EMeRGe studies. The deployment and results obtained in Asia will be the subject of separate publications.

Seasonal variation and origins of volatile organic compounds observed during 2 years at a western Mediterranean remote background site (Ersa, Cape Corsica)

Abstract: . An original time series of about 300 atmospheric measurements of a wide range of volatile organic compounds (VOCs) has been obtained at a remote Mediterranean station on the northern tip of Corsica Island (Ersa, France) over 25 months from June 2012 to June 2014. This study presents the seasonal variabilities of 25 selected VOCs, and their various associated sources. The VOC speciation was largely dominated by oxygenated VOCs (OVOCs) along with primary anthropogenic VOCs having a long lifetime in the atmosphere. VOC temporal variations are then examined. Primarily of local origin, biogenic VOCs exhibited notable seasonal and interannual variations, related to temperature and solar radiation ones. Anthropogenic compounds have shown an increasing concentration trend in winter (JFM months) followed by a decrease in spring/summer (AMJ/JAS months), and different concentration levels in winter periods of 2013 and 2014. OVOC concentrations were generally higher in summertime, mainly due to secondary and biogenic sources, whereas their concentrations during fall and winter were potentially more influenced by anthropogenic primary/secondary sources. Moreover, an apportionment factorial analysis was applied to a database comprising a selection of 14 primary individual or grouped VOCs by means of the positive matrix factorization (PMF) technique. A PMF solution composed of 5 factors was taken on. It includes a biogenic factor (which contributed 4 % to the total VOC mass), three anthropogenic factors (namely short-lived anthropogenic sources, evaporative sources, and long-lived combustion sources; which together accounted for 57 %), originating from either nearby or more distant emission areas (such as Italy and south of France); and a remaining one (39 %) connected to the regional background pollution. Variations in these main sources impacting VOC concentrations observed at the receptor site are also investigated at seasonal and interannual scales. In spring and summer, VOC concentrations observed at Ersa were the lowest in the 2-yr period, despite higher biogenic source contributions and since anthropogenic sources advected to Ersa were largely influenced by chemical transformations and vertical dispersion phenomena and were mainly of regional origins. During fall and winter, anthropogenic sources showed higher accumulated contributions when European air masses were advected to Ersa and could be associated to potential emission areas located in Italy and possibly more distant ones in central Europe. Higher VOC concentrations during winter 2013 compared to winter 2014 ones could be related to anthropogenic source contribution variations probably governed by emission strength of the main anthropogenic sources identified in this study together with external parameters, i.e. weaker dispersion phenomena and pollutant depletion. High frequency observations collected during several intensive field campaigns conducted at Ersa during the three summers 2012–2014 confirmed findings from bi-weekly samples in terms of summer concentration levels and source apportionment. However, they suggest that higher sampling frequency and temporal resolution, in particular to observe VOC concentrations variation during the daily cycle, are needed to confirm the deconvolution of the different anthropogenic sources identified by PMF approach. Finally, comparisons of the 25 months of observations at Ersa with VOC measurements conducted at 17 other European monitoring stations highlight the representativeness of the Ersa background station for monitoring seasonal variations in VOC regional pollution impacting continental Europe. Nevertheless, winter VOC concentration levels can significantly vary between sites, pointing out spatial variations in anthropogenic source contributions. As a result, Ersa concentration variations in winter were more representative of VOC regional pollution impacting central Europe. Interannual and spatial VOC concentration variations in winter were also significantly impacted by synoptic phenomena influencing meteorological conditions observed in continental Europe, suggesting that short observation periods may reflect the variability of the identified parameters under the specific meteorological conditions of the studied period.

How alkaline compounds control atmospheric aerosol particle acidity

Abstract: . The acidity of atmospheric particulate matter regulates its mass, composition, and toxicity and has important consequences for public health, ecosystems and climate. Despite these broad impacts, the global distribution and evolution of aerosol particle acidity are unknown. We used the comprehensive atmospheric multiphase chemistry–climate model EMAC (ECHAM5/MESSy Atmospheric Chemistry) to investigate the main factors that control aerosol particle acidity and uncovered remarkable variability and unexpected trends during the past 50 years in different parts of the world. Aerosol particle acidity decreased strongly over Europe and North America during the past decades while at the same time it increased over Asia. Our simulations revealed that these particle acidity trends are strongly related to changes in the phase partitioning of nitric acid, production of sulfate in aqueous aerosols, and the aerosol hygroscopicity. It is remarkable that the aerosol hygroscopicity ( κ ) has increased in many regions following the particle pH. Overall, we find that alkaline compounds, notably ammonium and to a lesser extent crustal cations, regulate the particle pH on a global scale. Given the importance of aerosol particles for the atmospheric energy budget, cloud formation, pollutant deposition, and public health, alkaline species hold the key to control strategies for air quality and climate change.