CO₂ transport by urban plumes in the upper Spanish plateau

• Published in: The Science of the total environment Vol. 407; no. 17; pp. 4934 - 4938
• Main Authors: Pérez, Isidro A, Sánchez, M. Luisa, García, M. Ángeles, de Torre, Beatriz
• Format: Journal Article
• Language: English
• Published: Kidlington [Amsterdam; New York]: Elsevier Science 15.08.2009; Elsevier
• Subjects: Applied sciences; Atmospheric pollution; Carbon Dioxide - chemistry; Carbon Dioxide - physiology; Exact sciences and technology; Plant Physiological Phenomena; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Spain; Europe; Spain; Atmospheric condition; Pollutant behavior; Mixing process; Carbon dioxide; Troposphere; Environmental factor; Plume; CO; Atmospheric stability; Transport process; Spatial distribution; Atmospheric boundary layer; Greenhouse gas; RASS sodar; Observation data; Air pollution; Sodar; Richardson number; Concentration distribution; Boundary layer
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2009.05.037

CO₂ transport from two cities, Valladolid, over 20 km away and Palencia, over 40 km away from a rural site is analysed through three years of detrended CO₂ concentrations obtained near the surface. Meteorological data were obtained from a RASS sodar. Directional analysis by histogram of concentrations above the 95th percentile revealed three differing sectors, one associated to a rural origin and two linked to both cities. Modes indicated anticyclonic turning during plume travel, confirmed by the daily evolution of the wind direction. At night, the Valladolid concentration median was 6 ppm above the Palencia median, which was 2 ppm higher than the rural sector median. Monthly evolution of daily maxima evidenced the Valladolid plume influence in spring and September, whereas the Palencia plume was noticeable in October and November. Skewness analysis showed almost symmetric distributions in the Valladolid plume and right skewed distributions in the Palencia and rural sectors. This result was attributed to the different mixing of both plumes. Vertical gradients of wind speed, direction and potential temperature were also calculated, and evidenced a stratified structure of the lower atmosphere at night and an almost uniform layer during the day. Finally, the median gradient Richardson number showed the highest values, occasionally above 0.8 for the Valladolid sector, implying lower mixing with the environment in the Valladolid plume than in the Palencia plume.