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Analysis of the airflow at the centre of the upper plateau on the Iberian Peninsula and its link to CO 2 and CH 4 concentrations
Author(s) -
Pérez Isidro A.,
Sánchez M. Luisa,
García M. Ángeles,
Pardo Nuria,
FernándezDuque Beatriz
Publication year - 2017
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.5323
Subject(s) - plateau (mathematics) , atmosphere (unit) , troposphere , environmental science , atmospheric sciences , trajectory , climatology , airflow , smoothing , vegetation (pathology) , meteorology , geology , mathematics , physics , statistics , thermodynamics , medicine , mathematical analysis , pathology , astronomy
Air trajectories are useful tools to investigate the airflow and transport of substances released into the atmosphere. Web‐based models are widely used to calculate trajectories reaching places that are being studied. This article considers 6 years of air trajectories as of October 2010 together with CO 2 and CH 4 concentrations. A bivariate smoothing function that employs the radial distance and direction of the trajectory to the measuring site was used to form trajectory groups from the minima of this function. Varied radial and angular windows were assayed to investigate the behaviour of the smoothing function. Curves associated with the number of minima were L‐shaped and the windows selected corresponded to the ‘knee’ of the curves. Seven trajectory groups were considered to observe the response of the procedure against the radial distance and the direction. Seasonal evolution revealed the greatest radial extent for winter and the lowest for summer. Moreover, trajectories from the Atlantic Ocean were the most frequent. CO 2 and CH 4 concentrations were detrended using a linear function, and average trends were 2.34 and 0.0085 ppm year −1 , respectively. Annual cycles of detrended concentrations were very soft and were linked to the site's ecosystem. CO 2 presented one maximum in spring linked to substantial vegetation growth, and one minimum in summer, when vegetation dies and dispersion is maximum. CH 4 maximum was observed in winter although the minimum was found in summer and attributed to oxidation with the hydroxyl radical in the troposphere and to dispersion in this season. Analysis of concentration trends for the groups proposed revealed the opposite behaviour of both gases in summer. Finally, maximum CO 2 concentrations were marked by trajectories from North Africa affected by nearby cities, whereas minimum concentrations for both gases were noticeable for trajectories from the ocean in summer.