Local traffic contribution to black carbon horizontal and vertical profiles in compact urban areas

Urban air pollution is characterized by strong spatial gradients produced by the presence of heavily trafficked streets. Given the negative health effects of air pollution, decision makers are implementing policies to reduce air pollution by modifying traffic flows near activity patterns of vulnerable populations. However, to our knowledge, there is quite a lack of appropriate decision tools to support such modifications at neighborhood to street levels. Measured horizontal and vertical distributions of traffic air pollutants can help understanding the variation of concentrations at increasing distances from emitting roads. Yet, models are still necessary to estimate the contribution of local traffic to measured concentrations. The main objective of this work is to investigate the contribution of local traffic to black carbon horizontal and vertical profiles based on measurements and model simulations. We will discuss the degree of influence of the different streets on black carbon measured profiles in Barcelona

Accelerating atmospheric models using GPUs

Environmental models are simplified representations of an object or a process [1]. These models provide valuable information on the nature of real-world phenomena and systems [2], with many applications in science and engineering [3]. For example, environmental models play an increasingly important role in understanding the potential implications of climate change [4]. There are many types of models in the environmental sciences [5]. These models are often associated with large computational costs because of their complexity [6]. The model studied in this work, the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model (MONARCH), is an atmospheric model that currently runs in the MareNostrum supercomputer of the Barcelona Supercomputing Center (BSC), one of the Top-500 supercomputers in the world [7] [8]. MONARCH provides regional mineral dust forecasts to the World Meteorological Organization’s (WMO) Barcelona Dust Forecast Center (BDFC) and the Sand and Dust Storm Warning Advisory and Assessment System (SDS-WAS). MONARCH also provides global aerosol forecasts to the International Cooperative for Aerosol Prediction (ICAP) initiative

Testing simple models for street wind conditions in Barcelona

Street wind speed and direction drive models to estimate air quality levels at street scale. In this study, simple models are combined with a mesoscale meteorological model to provide wind conditions at street level. Then, wind speed and direction are evaluated using observations collected during an experimental campaign in April 2013 at street level in Barcelona, Spain. Overall, models considering street geometry give better estimates for both wind speed and direction than those assuming homogeneous terrain. For light winds, models tend to produce a large amount of error estimating wind direction

Impact of aerosol microphysical properties on mass scattering cross sections

We assessed the sensitivity of simulated mass scattering cross sections (αλsca [m2/g]) of three aerosol perturbed particle microphysical properties and derived constraintspecies to on these microphysical properties, suitable for the north-western Mediterranean basin, from a comparison between code calculations and observations. In detail, we calculated αλsca of mineral dust,organic carbon and sulfate at three wavelengths in the visible range with a T-matrix optical code, considering ±20%perturbations on size distribution, refractive index and mass density, and spheroids with two different axial ratios as shape perturbations. Then, we compared the simulation results with a set of observed αλsca of mineral dust, aged organics and ammonium sulfate sources provided by the Institute of Environmental Assessment and Water Research (IDAEA-CSIC) and representative of the north-western Mediterranean Basi

Foreign and domestic contributions to surface ozone in Spain

Tropospheric ozone (O3) exerts strong adverse impacts on human health, climate, vegetation, biodiversity, agricultural crop yields and thus food security. O3 is formed in the atmosphere through non-linear photochemical reactions involving volatile organic compounds (VOCs) and nitrogen oxides (NOx) precursors [1]. Furthermore, meteorological stagnation, high solar radiation, high temperatures and low precipitation favor the formation of tropospheric O3 at surface levels exceeding target regulatory values [2]. Due to the complex and poorly constrained physico-chemical O3 formation and removal pathways, no straightforward strategies currently exist for reducing O3. Currently, there are no observational methods that differentiate the origin of O3. Despite their inherent uncertainties, chemical transport models (CTMs) allow for the apportionment of the contribution of any source to O3 concentrations. The mass-transfer source apportionment method is an optimal approach to study the contribution of different sources to ozone levels [2]. In this study, we provide a quantitative estimation of the foreign and domestic contributions to surface ozone on Spain, relative to European countries and the contribution of hemispheric background ozone. For that, we use the CMAQISAM within the CALIOPE air quality modelling system to simulate the O3 dynamics over Europe quantify national contributions for the ozone season from May to October in 2015. We tag both O3 and its precursors, NOx and VOCs, from the different European countries, all the way through their lifetime, from emission to deposition

Cluster analysis of 4-day back trajectories arriving in the Barcelona Area, Spain, from 1997 to 2002

Structural parameters for chemisorption of atomic carbon above a Si(100) surface have been obtained through a Si35H 32 cluster model and a MINDO/3 hamiltonian. The most stable position has been found to be the bridge one when considering the unrelaxed surface. The stability increases about 14 kcal/mol when relaxation of the surface is allowed. Further research has been carried out using a reduced cluster model (SigH i2) at the ab initio Hartree-Fock level of calculation. Results confirm the increase of stability of the relaxed system. At this level, the binding energy is 90 kcal/mol for the unrelaxed surface and the stabilization when the surface is relaxed is of about 20% with respect to the non-relaxed surface.Postprint (published version

HERMESv3, a stand-alone multi-scale atmospheric emission modelling framework – part 2: the bottom–up module

We describe the bottom–up module of the High-Elective Resolution Modelling Emission System version 3 (HERMESv3), a Python-based and multi-scale modelling tool intended for the processing and computation of atmospheric emissions for air quality modelling. HERMESv3 is composed of two separate modules: the global_regional module and the bottom_up module. In a companion paper (Part 1, Guevara et al., 2019a) we presented the global_regional module. The bottom_up module described in this contribution is an emission model that estimates anthropogenic emissions at high spatial- (e.g. road link level,) and temporal- (hourly) resolution using state-of-the-art calculation methods that combine local activity and emission factors along with meteorological data. The model computes bottom–up emissions from point sources, road transport, residential and commercial combustion, other mobile sources, and agricultural activities. The computed pollutants include the main criteria pollutants (i.e. NOx, CO, NMVOCs (non-methane volatile organic compounds), SOx, NH3, PM10 and PM2.5) and greenhouse gases (i.e. CO2 and CH4, only related to combustion processes). Specific emission estimation methodologies are provided for each source and are mostly based on (but not limited to) the calculation methodologies reported by the European EMEP/EEA air pollutant emission inventory guidebook. Meteorologically dependent functions are also included to take into account the dynamical component of the emission processes. The model also provides several functionalities for automatically manipulating and performing spatial operations on georeferenced objects (shapefiles and raster files). The model is designed so that it can be applicable to any European country or region where the required input data are available. As in the case of the global_regional module, emissions can be estimated on several user-defined grids, mapped to multiple chemical mechanisms and adapted to the input requirements of different atmospheric chemistry models (CMAQ, WRF-Chem and MONARCH) as well as a street-level dispersion model (R-LINE). Specific emission outputs generated by the model are presented and discussed to illustrate its capabilities.This research has been supported by the Ministerio de Ciencia, Innovación y Universidades (grant no. CGL2016-75725-R), the Ministerio de Ciencia, Innovación y Universidades (grant no. RTI2018-099894-B-I00), the Ministerio de Ciencia, Innovación y Universidades (grant no. RYC-2015-18690), and the AXA Research Fund (grant no. AXA Research Fund).Peer ReviewedPostprint (published version

Impact of HONO sources on the performance of mesoscale air quality models

Nitrous acid (HONO) photolysis constitutes a primary source of OH in the early morning, which leads to changes in model gas-phase and particulate matter concentrations. However, state-of-the-art models of chemical mechanisms share a common representation of gas-phase chemistry leading to HONO that fails in reproducing the observed profiles. Hence, there is a growing interest in improving the definition of additional HONO sources within air quality models, i.e. direct emissions or heterogeneous reactions. In order to test their feasibility under atmospheric conditions, the WRF-ARW/HERMES/CMAQ modeling system is applied with high horizontal resolution (4 4 km2) to Spain for November 24e27, 2008. HONO modeled sources include: (1) direct emissions from on-road transport; NO2 hydrolysis on aerosol and ground surfaces, the latter with (2) kinetics depending exclusively on available surfaces for reaction and (3) refined kinetics considering also relative humidity dependence; and (4) photoenhanced NO2 reduction on ground surfaces. The DOMINO measurement campaign performed in El Arenosillo (Southern Spain) provides valuable HONO observations. Modeled HONO results are consistently below observations, even when the most effective scenario is assessed, corresponding to contributions of direct emissions and NO2 hydrolysis with the simplest kinetics parameterization. With the additional sources of HONO, PM2.5 predictions can be up to 14% larger in urban areas. Quantified impacts on secondary pollutants have to be taken as a low threshold, due to the proven underestimation of HONO levels. It is fundamental to improve HONO sources definition within air quality models, both for the scientific community and decision makers.Peer ReviewedPostprint (published version

Near real time evaluation of the spanish air quality forecast system: CALIOPE

The WRF-ARW/HERMES-EMEP/CMAQ/BSC-DREAM8b modelling system provides high resolution air quality predictions for 48h in Europe –EU12- (12x12 km2, 1h), the Iberian Peninsula and Balearic Islands –IP4- (4x4 km2, 1h) and Canary Islands –CAN2- (2x2 km2, 1h) since July 2007, under the framework of the CALIOPE project (Baldasano et al., 2008; http://www.bsc.es/caliope/). A near real time evaluation system has been developed and it is on-line and in operation since January, 2009. Non validated near real time air quality data from more than 400 surface stations are compared to ground-concentration predictions in Spain. Seven ozonosondes are used to test the performance of the model in reproducing O3 vertical structures in Europe, Spain and Canary Islands. Additionally, OMI images are used to qualitatively assess the vertical column densities of NO2 predicted for Europe.Postprint (published version

Atmospheric dispersion of airborne pollen evidenced by near-surface and columnar measurements in Barcelona, Spain

Hourly measurements of pollen near-surface concentration and lidar-derived profiles of particle backscatter coefficients and of volume and particle depolarization ratios during a 5-day pollination event observed in Barcelona, Spain, between 27 – 31 March, 2015, are presented. Maximum hourly pollen concentrations of 4700 and 1200 m-3 h-1 were found for Platanus and Pinus, respectively, which represented together more than 80 % of the total pollen. Everyday a clear diurnal cycle caused by the vertical transport of the airborne pollen was visible on the lidar-derived profiles of the backscatter coefficient with maxima usually reached between 12 and 15 UT. A method based on the lidar polarization capabilities was used to retrieve the contribution of the pollen to the total signal. On average the diurnal (9 – 17 UT) pollen aerosol optical depth (AOD) was 0.05 which represented 29 % of the total AOD, the volume and particle depolarization ratios in the pollen plume were 0.08 and 0.14, respectively, and the diurnal mean of the height of the pollen plume was found at 1.24 km. The dispersion of the Platanus and Pinus in the atmosphere was simulated with the Nonhydrostatic Multiscale Meteorological Model on the B grid at the Barcelona Supercomputing Center with a newly developed Chemical Transport Model (NMMB/BSC-CTM). Model near-surface daily concentrations were compared to our observations at two sites: in Barcelona and Bellaterra (12 km NE of Barcelona). Model hourly concentrations were compared to our observations in Barcelona.Peer ReviewedPostprint (author's final draft