Sub-continental transport mechanisms and pathways during two ozone episodes in northern Spain

International audienceTwo ozone episodes (occurring in June 2001 and June 2003) in the air quality monitoring network of the Basque Country (BC) are analyzed. The population information threshold was exceeded in many stations (urban, urban-background and rural). During this type of episodes, forced by a blocking anticyclone over the British Isles, ozone background concentrations over the area increase after the import of pollution from both, the continental Europe and the western Mediterranean areas (Gangoiti et al., 2002). For the present analysis, emphasis is made in the search for transport mechanisms, pathways and area sources contributing to the build-up of the episodes. Contributions from a selection of 17 urban and industrial conglomerates in the western European Atlantic (WEA) and the western Mediterranean (WM) are shown after the results of a coupled RAMS-HYPACT modelling system. Meteorological simulations are tested against both the high-resolution wind data recorded at the BC coastal area by a boundary layer wind-profiler radar (Alonso et al., 1998) and the wind soundings reported by the National Centres of Meteorology at a selection of European and north-African sites. Results show that during the accumulation phase of the episodes, background ozone concentrations increase in the whole territory as a consequence of transport from the Atlantic coast of France and the British Channel. For the peak phase, intrusions from new sources, located at the Western Mediterranean, Southern France, Ebro Valley, and, occasionally, the area of Madrid are added, resulting in a further increase in the ozone concentrations. Direct day and night transport within the north-easterly winds over the sea from the WEA source region, and night-time transport within the residual layer over continental areas (southern France, the Ebro Valley, and central Iberia) modulate the import sequence of pollutants and the local increase of ozone concentrations. The alternative direct use of low resolution meteorological data for the estimation of back-trajectories shows a more simple transport scheme with no contributions neither from the Western Mediterranean nor from the Madrid area

Study of the correlation between columnar aerosol burden, suspended matter at ground and chemical components in a background European environment

Although routinely monitored by ground based air quality networks, the particulate matter distribution could be eventually better described with remote sensing techniques. However, valid relationships between ground level and columnar ground based quantities should be known beforehand. In this study we have performed a comparison between particulate matter measurements at ground level at different cut sizes (10, 2.5 and 1.0 mm), and the aerosol optical depth obtained by means of a ground based sunphotometer during a multiinstrumental field campaign held in El Arenosillo (Huelva, Spain) from 28 June to 4 July 2006. All the PM fractions were very well correlated with AOD with correlation coefficients that ranged from 0.71 to 0.81 for PM10, PM2.5 and PM1. Furthermore, the influence of the mixing layer height in the correlations was explored. The improvement in the correlation when the vertical distribution is taken into account was significant for days with a homogeneous mixing layer. Moreover, the chemical analysis of the individual size fractions allowed us to study the origin of the particulate matter. Secondary components were the most abundant and also well correlated in the three size fractions; but for PM10 fraction, chemical species related to marine origin were best correlated. Finally, we obtained a relationship between MODIS L3 AOD from collection 5.1 and the three PM cut sizes. In spite of being a relatively clean environment, all the techniques were able to capture similar day to day variations during this field campaign.Peer ReviewedPostprint (published version

Climatic Feedbacks and Desertification: The Mediterranean Model

Abstract Mesometeorological information obtained in several research projects in southern Europe has been used to analyze perceived changes in the western Mediterranean summer storm regime. A procedure was developed to disaggregate daily precipitation data into three main components: frontal precipitation, summer storms, and Mediterranean cyclogenesis. Working hypotheses were derived on the likely processes involved. The results indicate that the precipitation regime in this Mediterranean region is very sensitive to variations in surface airmass temperature and moisture. Land-use perturbations that accumulated over historical time and greatly accelerated in the last 30 yr may have induced changes from an open, monsoon-type regime with frequent summer storms over the mountains inland to one dominated by closed vertical recirculations where feedback mechanisms favor the loss of storms over the coastal mountains and additional heating of the sea surface temperature during summer. This, in turn, favors Mediterranean cyclogenesis and torrential rains in autumn–winter. Because these intense rains and floods can occur anywhere in the basin, perturbations to the hydrological cycle in any part of the basin can propagate to the whole basin and adjacent regions. Furthermore, present levels of air pollutants can produce greenhouse heating, amplifying the perturbations and pushing the system over critical threshold levels. The questions raised are relevant for the new European Union (EU) water policies in southern Europe and for other regions dominated by monsoon-type weather systems

Understanding the local and remote source contributions to ambient O3 during a pollution episode using a combination of experimental approaches in the Guadalquivir valley, southern Spain

The Guadalquivir Valley is one of three major O3 hotspots in Spain. An airborne and surface measurement campaign was carried out from July 9th to 11th, 2019 to quantify the local/regional O3 contributions using experimental approaches. Air quality and meteorology data from surface measurements, a microlight aircraft, a helium balloon, and remote sensing data (TROPOMI-NO2-ESA) were used to obtain the 3D distribution of O3 and various tracer pollutants. O3 accumulation over 2.5 days started with inputs from oceanic air masses transported inland by sea breezes, which drew O3 and its precursors from a local/regional origin to the northeastern end of the basin. The orographic–meteorological setting of the valley caused vertical recirculation of the air masses inside the valley that caused the accumulation by increasing regional background O3 concentration by 25–30 ppb. Furthermore, possible Mediterranean O3 contributions and additional vertical recirculation through the entrainment zone of the convective boundary layer also contributed. Using particulate matter finer than 2.5 μm (PM2.5), ultrafine particles (UFP), and black carbon (BC) as tracers of local sources, we calculated that local contributions increased regional O3 levels by 20 ppb inside specific pollution plumes transported by the breeze into the valley, and by 10 ppb during midday when flying over an area with abundant agricultural burning during the morning. Air masses that crossed the southern boundaries of the Betic system at mid-altitude (400–1850 m a.s.l.) on July 10th and 11th may have provided additional O3. Meanwhile, a decreasing trend at high altitudes (3000–5000 m a.s.l.) was observed, signifying that the impact of stratospheric O3 intrusion decreased during the campaign

Cysteamine Suppresses Invasion, Metastasis and Prolongs Survival by Inhibiting Matrix Metalloproteinases in a Mouse Model of Human Pancreatic Cancer

Background: Cysteamine, an anti-oxidant aminothiol, is the treatment of choice for nephropathic cystinosis, a rare lysosomal storage disease. Cysteamine is a chemo-sensitization and radioprotection agent and its antitumor effects have been investigated in various tumor cell lines and chemical induced carcinogenesis. Here, we investigated whether cysteamine has anti-tumor and anti-metastatic effects in transplantable human pancreatic cancer, an aggressive metastatic disease. Methodology/Principal Findings: Cysteamine’s anti-invasion effects were studied by matrigel invasion and cell migration assays in 10 pancreatic cancer cell lines. To study mechanism of action, we examined cell viability and matrix metalloproteinases (MMPs) activity in the cysteamine-treated cells. We also examined cysteamine’s anti-metastasis effect in two orthotopic murine models of human pancreatic cancer by measuring peritoneal metastasis and survival of animals. Cysteamine inhibited both migration and invasion of all ten pancreatic cancer cell lines at concentrations (,25 mM) that caused no toxicity to cells. It significantly decreased MMPs activity (IC50 38–460 mM) and zymographic gelatinase activity in a dose dependent manner in vitro and in vivo; while mRNA and protein levels of MMP-9, MMP-12 and MMP-14 were slightly increased using the highest cysteamine concentration. In vivo, cysteamine significantly decreased metastasis in two established pancreatic tumor models, although it did not affect the size of primary tumors. Additionally, cysteamin

Mesoscale circulations over complex terrain in the Valencia coastal region, Spain – Part 2: Modeling CO₂ transport using idealized surface fluxes

International audienceVertical profiles of CO2 concentration were collected during an intensive summer campaign in a coastal complex-terrain region within the frame of the European Project RECAB (Regional Assessment and Modelling of the Carbon Balance in Europe). The region presents marked diurnal mesoscale circulation patterns. These circulations result in a specific coupling between atmospherically transported CO2 and its surface fluxes. To understand the effects of this interaction on the spatial variability of the observed CO2 concentrations, we applied a high-resolution transport simulation to an idealized model of land biotic fluxes. The regional Net Ecosystem Exchange fluxes were extrapolated for different land-use classes by using a set of eddy-covariance measurements. The atmospheric transport model is a Lagrangian particle dispersion model, driven by a simulation of the RAMS mesoscale model. Our simulations were able to successfully reproduce some of the processes controlling the mesoscale transport of CO2. A semi-quantitative comparison between simulations and data allowed us to characterize how the coupling between mesoscale transport and surface fluxes produced CO2 spatial gradients in the domain. Temporal averages in the simulated CO2 field show a covariance between flux and transport consisting of: 1) horizontally, a CO2 deficit over land, mirrored by a CO2 excess over the sea and 2) vertically, the prevalence of a mean CO2 depletion between 500 and 2000 m, and a permanent build-up of CO2 in the lower levels