Feasibility of Ceilometers Data to Estimate Radiative Forcing Values: Application to Different Conditions around the COVID-19 Lockdown Period

The authors would like to acknowledge to ACTRIS-SPAIN (CGL2017-90884-REDIT), coordinated by Granada University, for providing quality-assured aerosol measurements and acknowledge to AERONET and COPERNICUS Global Land Services for sun-photometer and satellite quality-assured data processing and distribution. The authors also acknowledge to the Atmospheric Modelling & Weather Forecasting Group in the University of Athens, the Earth Science Dpt. from the Barcelona Supercomputing Centre and the Naval Research laboratory for the provision of SKIRON, DREAM/BSCDREAM8b and NAAPs aerosol maps, respectively. Philippe Dubuisson, the developer of the GAME code, is specially acknowledged. Furthermore, the developers of the HYSPLIT model are also acknowledged. The task of identifying African dust events and quantifying the dust contribution in the regions of the Spanish territory has been routinely carried out in the framework of projects funded by the Spanish ministry for the Ecological Transition (MITECO).In this study, the feasibility of using ceilometer signals to retrieve radiative forcing values is evaluated. The Global Atmospheric Model (GAME) radiative transfer model is used to estimate the shortwave and longwave radiative forcing using an aerosol parameterization based on AERONET data and vertical profiles from a Lufft CHM-15k Nimbus ceilometer. First, eight cases confirmed as dusty days are analyzed to check the feasibility of using ceilometer profiles to feed GAME. The obtained radiative forcing estimates are in good agreement with the literature showing negative values in the short wave (SW) (cooling effect) and positive values in the long wave (LW) (heating effect), both at all levels. As in the literature, radiative forcing estimates show a strong dependence on variations in the aerosol optical depth (AOD), solar zenith angle (θz), surface temperature (ST), and single scattering albedo at 440 nm (SSA440). Thus, GAME can be fed using ceilometer measurements obtaining reliable results. Then, as the temporal evolution of the AOD440 between 27 January and 15 June compared to the 6-year weekly AERONET AOD440 average (from 2014 to 2019) shows a decrease because of the lockdown imposed in Spain due to the COVID-19, a total of 37 radiative forcing calculations without African dust, divided into 8 scenarios, are performed in order to check the effect of the lockdown measures in the radiative forcing. It is shown that the decrease in the AOD, during the lockdown, caused a decrease in the cooling effect in the SW spectral range at all levels. Besides, the increase in the ST increased the heating effect of the aerosols in the LW at the top of the atmosphere and the presence of pollution and absorbing particles (SSA440 < 0.90) caused an increase of the heating effect in the LW at the surface. Therefore, the observed variations in the radiative forcing estimates before and during the lockdown are directly related with the decrease in emissions of aerosols related to human activities.Spanish Ministry of Economy and Competitivity (CRISOL) CGL2017-85344-RMadrid Regional Government (TIGAS-CM) Y2018/EMT-5177Maria Sklodowska-Curie IF 796539H2020 programme from the European Union 654109; 87111

Evidence that Nitric Oxide is Involved in the Blood Pressure Lowering Effect of the Peptide AVFQHNCQE in Spontaneously Hypertensive Rats

AVFQHNCQE is an antihypertensive nonapeptide obtained from a chicken foot protein hydrolysate. The present study aims to investigate the mechanisms involved in its blood pressure (BP)-lowering effect. Male (17–20 weeks old) spontaneously hypertensive rats (SHR) were used in this study. Rats were divided into two groups and orally administered water or 10 mg/kg body weight (bw) AVFQHNCQE. One hour post administration, animals of both groups were intra peritoneally treated with 1 mL of saline or with 1 mL of saline containing 30 mg/kg bw Nω-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthesis, or with 1 mL of saline containing 5 mg/kg bw indomethacin, which is an inhibitor of prostacyclin synthesis (n = 6 per group). Systolic BP was recorded before oral administration and six hours after oral administration. In an additional experiment, SHR were administered water or 10 mg/kg bw AVFQHNCQE (n = 6 per group) and sacrificed six hours post administration to study the mechanisms underlying the peptide anti-hypertensive effect. Moreover, the relaxation caused by AVFQHNCQE in isolated aortic rings from Sprague Dawley rats was evaluated. The BP-lowering effect of the peptide was not changed after indomethacin administration but was completely abolished by L-NAME, which demonstrates that its anti-hypertensive effect is mediated by changes in endothelium-derived NO availability. In addition, AVFQHNCQE administration downregulated aortic gene expression of the vasoconstrictor factor endothelin-1 and the endothelial major free radical producer NADPH. Moreover, while no changes in plasma ACE activity were observed after its administration, liver GSH levels were higher in the peptide treated group than in the water group, which demonstrates that AVFQHNCQE presents antioxidant properties

Wind and turbulence relationship with NO2 in an urban environment: a fine-scale observational analysis

It is well known that meteorology plays an important role in the diurnal evolution of pollutants, especially those variables related to atmospheric dispersion. Most studies typically relate the concentration of some pollutants with wind speed from conventional anemometers; however, the use of turbulence variables is less common, in part because the needed instruments are not so typical in standard air-quality stations. In this work, we compare the wind-NO2 relationship with the turbulence-NO2 one using observational data from two field campaigns developed in Madrid (winter and summer). The turbulence data comes from two sonic anemometers deployed at different locations: one close to the street and the other at the top of a nearby tall building. The results indicate that the turbulent variables correlate better with the pollutant concentration than the wind speed when using data from the street sonic, while the contrary is found when using the terrace sonic. These data are also used to perform a fine-scale analysis of the turbulent diffusion-NO2 behaviour during a very-stable period in winter, when the turbulence typically shows a decrease in the evening transition, causing the highestNO2 concentrations. Conversely, under these conditions, the formation of thermally-driven winds is also favoured later in the night, which favours the pollutant dispersion and cleaning of the air. The important role of these dynamical processes on the NO2 evolution highlights the importance of the correct understanding of small-scale atmospheric processes to understand their relationship with the concentration of pollutants

Spanish activities in the framework of the CHARMEX project since 2009: a summary

The ChArMEx (Chemistry-Aerosol Mediterranean Experiment) project is a French initiative aiming at developing and coordinating regional research actions for a scientific assessment of the present and future state of the atmospheric environment in the Mediterranean Basin, and of its impacts on the regional climate, air quality, and marine biogeochemistry. The target of ChArMEx is short-lived particulate and gaseous tropospheric trace species. In 2009 the project gained internationalization with the organization of the first international workshop held in Toulouse, France. Spain was the most represented country (after France) with 7 groups and 10 researchers. Up to date, the Spanish groups involved in ChArMEx have conducted research in several fields. Among them it is worth noting: a 3-year (2010 – 2012) in-situ study over a regional background environment in Mallorca plus 3 intensive measurement campaigns in that period; the installation in Mallorca and in the Sierra Nevada of two autonomous total deposition samplers performing weekly dust deposition on a network basis; and intensive in-situ and remote sensing measurements in Barcelona in thesummer 2012 ChArMEx pre-campaign to give support to airborne observations. The paper gives a summary of all the activities led by Spanish researchers in the framework of ChArMEx. Preliminary results of the 3-year in-situ study in Mallorca and of the summer 2012 pre-campaign, as well as a brief description of the summer 2013 main campaign are presented.Peer ReviewedPostprint (published version

Vertical characterization of fine and coarse dust particles during an intense Saharan dust outbreak over the Iberian Peninsula in springtime 2021

An intense and long-lasting Saharan dust outbreak crossed the Iberian Peninsula (IP) from the southwest (SW) to the northeast (NE) from 25 March until 7 April 2021. This work aims to assess the optical and mass contribution of both fine and coarse dust particles along their transport. Five Iberian lidar stations were monitoring the transport and evolution of the Saharan dust particles, i.e. El Arenosillo/Huelva, Granada, Torrejón/Madrid and Barcelona in Spain, and Évora in Portugal. The particular meteorological conditions determined the aerosol scenario along the overall dust event, differing in the first part of the event (25–31 March), in which the strongest dust incidence occurred on 29–31 March at the south and central stations and 1 April at Barcelona, from the second one (1–7 April). The use of the two-step POLIPHON algorithm showed the relevance of using polarized lidar measurements for separating the aerosol properties of dust fine and coarse particles as an added value. Both the fine dust (Df) and coarse dust (Dc) components of the total particle backscatter coefficient (total dust, DD¿=¿Dc¿+¿Df) were separately derived. The dust plume was well-mixed with height and no significant differences were found in the vertical structure of both the Dc and Df particle backscatter coefficients. From the beginning of the dust outbreak until 1 April, the vertical Df¿¿DD mass ratio was nearly constant in time at each station and also in altitude with values of ~¿10¿%. Moreover, the mean dust optical depth at 532¿nm was decreasing along that dust pathway, reporting values from SW to NE stations of 0.34 at El Arenosillo/Huelva, 0.28 at Granada, 0.20 at Évora, 0.28 at Torrejón/Madrid, and 0.14 at Barcelona, although its Df¿¿DD ratio remained almost constant (28¿%–30¿%). A similar pattern was found for the total dust mass loading and its Df¿¿DD ratio, i.e. mostly decreasing mean mass values were reported, being constant in its Df¿¿DD ratio (~¿10¿%) along the SW–NE dust pathway. In addition, the episode-mean centre-of-mass height increased with latitude overall, showing a high variability, being greater than 0.5¿km at the southern sites (El Arenosillo/Huelva, Granada, Évora) and ~¿1.0¿km at Torrejón/Madrid and Barcelona. However, despite the relatively high intensity of the dust intrusion, the expected ageing of the dust particles was hardly observed, by taking into account the minor changes found in the contribution and properties of the coarse and fine dust particles. This is on the basis that the IP is relatively close to the Saharan dust sources and then, under certain dust transport conditions, any potential ageing processes in the dust particles remained unappreciated. The following must be highlighted: the different relative contribution of the fine dust particles to the total dust found for their optical properties (~¿30¿%) associated with the radiative effect of dust, with respect to that for the mass features (~¿10¿%) linked to air quality issues, along the overall dust event by crossing the IP.This research has been supported by the Spanish Ministry of Science and Innovation (grant no. PID2019-104205GB-C21/AEI/10.13039/501100011033).Peer ReviewedPostprint (published version

ACTRIS ACSM intercomparison – Part 2: Intercomparison of ME-2 organic source apportionment results from 15 individual, co-located aerosol mass spectrometers

Chemically resolved atmospheric aerosol data sets from the largest intercomparison of the Aerodyne aerosol chemical speciation monitors (ACSMs) performed to date were collected at the French atmospheric supersite SIRTA. In total 13 quadrupole ACSMs (Q-ACSM) from the European ACTRIS ACSM network, one time-of-flight ACSM (ToF-ACSM), and one high-resolution ToF aerosol mass spectrometer (AMS) were operated in parallel for about 3 weeks in November and December~2013. Part 1 of this study reports on the accuracy and precision of the instruments for all the measured species. In this work we report on the intercomparison of organic components and the results from factor analysis source apportionment by positive matrix factorisation (PMF) utilising the multilinear engine 2 (ME-2). Except for the organic contribution of mass-to-charge ratio m/z 44 to the total organics (f44), which varied by factors between 0.6 and 1.3 compared to the mean, the peaks in the organic mass spectra were similar among instruments. The m/z 44 differences in the spectra resulted in a variable f44 in the source profiles extracted by ME-2, but had only a minor influence on the extracted mass contributions of the sources. The presented source apportionment yielded four factors for all 15 instruments: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA), biomass burning-related organic aerosol (BBOA) and secondary oxygenated organic aerosol (OOA). ME-2 boundary conditions (profile constraints) were optimised individually by means of correlation to external data in order to achieve equivalent / comparable solutions for all ACSM instruments and the results are discussed together with the investigation of the influence of alternative anchors (reference profiles). A comparison of the ME-2 source apportionment output of all 15 instruments resulted in relative standard deviations (SD) from the mean between 13.7 and 22.7 % of the source's average mass contribution depending on the factors (HOA: 14.3 ± 2.2 %, COA: 15.0 ± 3.4 %, OOA: 41.5 ± 5.7 %, BBOA: 29.3 ± 5.0 %). Factors which tend to be subject to minor factor mixing (in this case COA) have higher relative uncertainties than factors which are recognised more readily like the OOA. Averaged over all factors and instruments the relative first SD from the mean of a source extracted with ME-2 was 17.2 %.JRC.H.2-Air and Climat

Actividades españolas en el marco del proyecto CHARMEX desde 2009: un resumen

El proyecto ChArMEx (Chemistry-Aerosol Mediterranean Experiment) es una iniciativa francesa cuyo objetivo es desarrollar y coordinar las acciones de investigación regionales para una evaluación científica de la situación actual y el futuro del medio ambiente atmosférico en la cuenca mediterránea. Los grupos españoles que participan en ChArMEx llevan a cabo investigaciones en varios campos. Entre ellos cabe señalar: un estudio in-situ de 3 años (2010-2012) en un entorno regional de fondo en Mallorca; la instalación en Mallorca y Granada de dos nuevos colectores de deposición autónomos que colectan la deposición de polvo semanalmente; mediciones intensivas in situ y de teledetección en Barcelona en el verano 2012 durante la pre-campaña ChArMEx; y mediciones de teledetección intensivos en Barcelona y Granada en el verano de 2013 durante la campaña ChArMEx / ADRIMED. Este manuscrito da un resumen de todas las actividades conducidas por investigadores españoles hasta ahora en el marco de ChArMEx. Se presentan resultados preliminares del estudio in-situ de 3 años en Mallorca y parte de las campañas de verano de 2012 y 2013.Peer ReviewedPostprint (published version

ACTRIS ACSM intercomparison – Part 1: Reproducibility of concentration and fragment results from 13 individual Quadrupole Aerosol Chemical Speciation Monitors (Q-ACSM) and consistency with co-located instruments

As part of the European ACTRIS project, the first large Quadrupole Aerosol Chemical Speciation Monitor (Q-ACSM) intercomparison study was conducted in the region of Paris for 3 weeks during the late-fall – early-winter period (November–December 2013). The first week was dedicated to the tuning and calibration of each instrument, whereas the second and third were dedicated to side-by-side comparison in ambient conditions with co-located instruments providing independent information on submicron aerosol optical, physical, and chemical properties. Near real-time measurements of the major chemical species (organic matter, sulfate, nitrate, ammonium, and chloride) in the non-refractory submicron aerosols (NR-PM1) were obtained here from 13 Q-ACSM. The results show that these instruments can produce highly comparable and robust measurements of the NR-PM1 total mass and its major components. Taking the median of the 13 Q-ACSM as a reference for this study, strong correlations (r2 > 0.9) were observed systematically for each individual Q-ACSM across all chemical families except for chloride for which three Q-ACSMs showing weak correlations partly due to the very low concentrations during the study. Reproducibility expanded uncertainties of Q-ACSM concentration measurements were determined using appropriate methodologies defined by the International Standard Organization (ISO 17025, 1999) and were found to be 9, 15, 19, 28, and 36 % for NR-PM1, nitrate, organic matter, sulfate, and ammonium, respectively. However, discrepancies were observed in the relative concentrations of the constituent mass fragments for each chemical component. In particular, significant differences were observed for the organic fragment at mass-to-charge ratio 44, which is a key parameter describing the oxidation state of organic aerosol. Following this first major intercomparison exercise of a large number of Q-ACSMs, detailed intercomparison results are presented, along with a discussion of some recommendations about best calibration practices, standardized data processing, and data treatment.JRC.H.2-Air and Climat

Short-Term Effects of Ozone on Mortality: Comparative Analysis of Urban and Suburban Zones in Madrid (Spain)

A large number of papers published in the last decades are related to the effect of ozone exposure on mortality worldwide. Several studies have been performed to investigate the effect of ozone on mortality in Madrid (Spain), but the findings of these local reports were focused only on the Madrid city. The association of daily concentrations of ozone with daily mortality was investigated using autoregressive Poisson regression models. This study explores the effects of ozone on all causes except accidents, cardiovascular and respiratory short-term mortality in two areas of the Madrid region: an urban area constituted by the Madrid municipality and an industrial sub-urban area surrounding the city. Using three years of daily data (2003-2005), it was analyzed the all-ages populations and the over-64 age groups. The average ozone concentrations over the study period were 54.07 ± 27.17 μg/m3 in the Madrid municipality and 70.09 ± 32.96 μg/m3 in the sub-urban municipalities surrounding the city. Our results in the all-ages group indicated that 0.69% of all causes except accidents, 1.15% of cardiovascular and 1.56% of respiratory daily deaths, respectively, could be attributed to exposure to ozone in the Madrid city, whereas 11.69% of daily respiratory deaths were attributable to ozone exposure in the Madrid sub-urban surroundings. Our results show a clear association between mortality and ozone exposure. The spatial heterogeneity of ozone effects on short-term mortality throughout the Madrid region may have implications for local environmental policies and also for social and health services planning.This research was funded by the European Commission FP7-ENV project “Health Risk from Environmental Pollution Levels in Urban Systems (HEREPLUS)”, contract 212854. We wish give our thanks to the following contributors: the Madrid Community Institute of Statistics for supplying the mortality data; the Madrid Municipality authority and the Madrid Community government for providing the environmental data; the Palynology Network of the Madrid Regional Health Authority for supplying the pollen data and, the National Centre of Epidemiology for providing the influenza data. In addition, we also wish to give our special thanks to Julio Díaz and Cristina Linares for their support in the statistical analysis

Low-Cost sensors for urban air quality monitoring: preliminary laboratory and in-field tests within the TECNAIRE-CM project

Low-cost sensor technology can potentially make revolutionary changes in our current air pollution monitoring paradigm in urban areas. However, the widespread adoption of low-cost sensor technology is still not feasible due to a number of limitations regarding sensitivity, accuracy and comparability. In this study we report the results from preliminary laboratory and in-field tests carried out within the TECNAIRE-CM project for commercial NO2 and O3 sensors including both, solid-state and electrochemical technologies. The ultimate goal is to understand the current capabilities of this technology and the prospects to incorporate it in both research and routine measurement or urban air quality. We found significant performance differences although none of the devices tested could provide satisfactory results in real-world conditions. We conclude that unit-specific advanced statisticalcalibration methods are needed to obtain reliable results with the low cost sensors devices in urban areas