Impact of the COVID-19 Lockdown in a European Regional Monitoring Network (Spain): Are We Free from Pollution Episodes?

The impact of the lockdown, during the period from March to June in 2020, upon the air quality of the Basque Country in northern Spain is analyzed. The evaluation accounts for the meteorology of the period. Daily and sub-daily analysis of aerosol and ozone records show that the territory was repeatedly affected by episodes of pollutants from outer regions. Three episodes of PM10 and ten of PM2.5 were caused by transported anthropogenic European sulfates, African dust, and wildland fires. The region, with a varied orographic climatology, shows high and diverse industrial activity. Urban and interurban road traffic of the region decreased by 49% and 53%, respectively, whereas industrial activity showed a lower reduction of 20%. Consequently, the average concentrations of NO2 in the cities during the period fell to 12.4 µg·m−3 (−45%). Ozone showed up to five exceedances of the WHOAQG for the daily maximum 8-h average in both rural and urban sites, associated with transport through France and the Bay of Biscay, under periods of European blocking anticyclones. However, averages showed a moderate decrease (−11%) in rural environments, in line with the precursor reductions, and disparate changes in the cities, which reproduced the weekend effect of their historical records. The PM10 decreased less than expected (−10% and −21%, in the urban and rural environments, respectively), probably caused by the modest decrease of industrial activity around urban sites and favorable meteorology for secondary aerosol formation, which could also influence the lower changes observed in the PM2.5 (−1% and +3% at the urban and rural sites, respectively). Consequently, in a future low NOx traffic emission scenario, the inter-regional PM and ozone control will require actions across various sectors, including the industry and common pollution control strategies.This research was funded by the Basque Government and the University of the Basque Country (GIC15/152 and GIU13/03) and by the Environment Vice-Department of the Basque Government for the measurement of biogenic volatile organic compounds in Valderejo Natural Park

Galernas: A history of coastally trapped disturbances (2003−2020) with hidden frontogenesis in the Bay of Biscay

Galerna is the term accepted for an abrupt westerly change that affects the north coast of Spain. The wind surge travels from the mid-north coast of Spain to France, generally reaching their maximum intensity at the Basque Coast, and cuts off a period of hot weather, clear skies, and calm conditions at sea. The galernas have a large history of shipwrecks and fishermen deaths. They have been characterized as coastally trapped disturbances (CTD) and their propagation, enhanced with the local formation of a micro-front, was documented to behave like a density current. Alternatively, synoptic fronts have also been reported to cause galernas, considered to be more intense than those generated by a local micro-front. In this article we have generated the first climatology (2003–2020) of these events based on an objective identification methodology. The developed Event Identification Software (EIS), based on both 10-min surface station data and hourly ERA5 reanalysis fields, together with a new Front Identification Scheme (FIS) have enabled a deeper study into the origin and development of these micro-fronts, and a more comprehensive exploration of the interaction of the oceanic fronts entering the Bay of Biscay. Our results show that the area receives an average of four to five relatively intense galernas (Vmax > 50 km h−1) per year. Their number shows a great interannual variability (from one to seven) and a marked seasonality: May and June concentrate the largest fraction (almost one episode each year) and practically no episodes in winter. They occur more frequently between noon and the late afternoon, where the most intense wind records concentrate. Very strong galernas (Vmax > 72 km h−1) have occurred in all 18 years, can happen in any month from February to November, and their monthly distribution does not show the mentioned seasonality. On the contrary, the highest rates of temperature decrease across the galerna front in the coastal stations (−∆T/0.5 h > 4 °C) do have a stronger seasonality, with May and June concentrating a relatively large number of cases with a more abrupt temperature drop. The FIS shows that most of the galernas (83.5%) have a local origin inside the Bay of Biscay, and only a few ones (16.5%) are caused by oceanic fronts initiated out of the region. The local frontogenesis is more frequently initiated by the relatively cold marine southwesterly pre-frontals preceding a parent oceanic front and blowing against the warm continentals inside the Bay of Biscay, after being ducted along the north and northwestern coast of Spain. This hidden local frontogenesis, first revealed by the FIS, seems to be enhanced by the observed lee troughing, which could have both a thermal and dynamic origin, acting simultaneously after the intense Foehn at the coastal strip, preceding the formation of the galerna front. The local front enhancement appears to be the reason for the apparent jump of the primary front, which may eventually weaken, and even disappear, as the galerna front sharpens. Even during the more occasional frontal galernas, directly caused by the westerlies or north-westerlies behind the oceanic front, their eastward propagation is more rapid over the coastal area. The front deforms in shape and may cause its characteristic unexpected/abrupt irruption. All the EIS detected galernas, even the frontal ones, are wind reversals caused by a coastally trapped marine boundary layer. The upper-level ridge over Europe, observed in all of them, seems to be a synoptic ingredient for their development, preventing the eastward propagation of Atlantic depressions and enhancing at the same time the temperature and pressure gradients between the marine and continental air masses.The authors wish to thank the Basque Government and the University of the Basque Country UPV/EHU as the source of our main financial support: GIA consolidated Research Groups (https://www.ehu.eus/es/web/gia) IT1057-16 (GIC15/152) and GIU13/03. These financing bodies have played an exclusively economic role in the study

Almacenamiento y Transmisión de Imágenes Digitales: cómo reducir la cantidad de datos

Metodología: Problemas Nivel educativo: Grado Duración (en horas): De 41 a 50 horasEste ABP requiere una dedicación del estudiante de 21 horas presenciales y 26.5 no presenciales. Con él se trabajan dos temas de la asignatura (producto escalar y diagonalización de matrices/ autovalores y autovectores), como medio para el aprendizaje final del método de Descomposición en Valores Singulares, que dará solución al problema estructurante propuesto. Con él, además de competencias específícas, se trabajan competencias transversales de la titulación. El punto de partida es una fotografía, muestra de todas las fotografías que un ingeniero recién licenciado debe enviar desde su primer destino en África, en el que hay problemas en las comunicaciones. Tras discutir y consensuar los objetivos de aprendizaje, cuya consecución permitirá finalmente resolver el problema, los estudiantes comienzan la realización de las actividades propuestas. Gran parte de ellas se realizan en grupos de tres personas; otras (fundamentalmente actividades de recapitulación), de manera individual. Se hace un seguimiento continuo de las actividades y se ofrece retroalimentación del aprendizaje, estando la profesora a disposición de los alumnos, tanto dentro como fuera del aula, para guiarles en la realización de dichas actividades. Finaliza el ABP con la entrega de un informe y la realización de una exposición oral. El empleo de software matemático queda integrado en las actividades