M. Ángeles García

• Professor (Full) at University of Valladolid

The port of Cartagena, south-east Spain, is noted for its intense activity. This paper presents the influence of the COVID-19 pandemic on the recorded levels of six pollutants. Fifteen years of measurements were used, with two objectives. The first was to investigate how these pollutants evolved, together with their usual cycles. The second objecti...

In recent years, by expanding cities, air pollution has become one of the most important problems caused by humans. Tehran, as the capital of Iran, is expanding gradually and its population is rising day by day. Therefore, the increase in human activities causes many problems, such as air pollution, in this area. In this study, data from Sentinel-5...

This paper presents a long-term analysis of ambient PM10 concentrations measured at a background station in Spain, using backward trajectories generated with the HYSPLIT model, together with the identification of synoptic patterns and a fuzzy clustering analysis, to identify the sources present and evaluate their relationship with meteorological va...

Monthly terrestrial precipitation was studied based on a dataset of 118 years covering the world. Different statistical indicators such as the median, the interquartile range, the Yule-Kendall index and the robust kurtosis were analysed taking into account time and latitudes in order to reach conclusions about the evolution of precipitation dependi...

CO2 and CH4 outliers may have a noticeable impact on the trend of both gases. Nine years of measurements since 2010 recorded at a rural site in northern Spain were used to investigate these outliers. Their influence on the trend was presented and two limits were established. No more than 23.5% of outliers should be excluded from the measurement ser...

This paper analyses surface ozone measurements at five stations in an urban area (Valladolid) in the upper Spanish plateau over the period 2002–2020. Temporal evolutions, the relationship between ozone and other pollutants such as nitrogen oxides, and the assessment of the ozone concentration trend during the study period were analysed. Daily evolu...

Climate change has been the subject of intensive research in recent decades, with temperature being one of the key variables that helps to characterise the Earth's climate. This study analyses the main features and temperature trend recorded on the Mediterranean coast. Daily maximum and minimum temperatures recorded over 40 years (1965–2004) at 52...

Pollution control is based on an exhaustive knowledge of concentration distributions. This study analyses a detailed database of NO2, O3, PM10 and PM2.5 in England and Wales over the period 2007-2011. Daily and annual means were considered in a 1-km spatial resolution. Histograms revealed a shape like a sawtooth. The interval was wide for NO2 and O...

The influence of urban plumes on the final measurements recorded at rural stations is an issue which has rarely been touched upon in great detail. A better knowledge of local and regional sources of atmospheric CO2 and CH4 evolution over time and space provides policy-makers with the right awareness when acting to improve air quality. Assessing the...

Outliers are frequent in CO 2 and CH 4 observations at rural sites. The aim of this paper is to establish a procedure based on the lag-1 autocorrelation to form measurement groups, some of which include outliers, and the rest include regular measurements. Once observations are classified, a second objective is to determine the number of harmonics i...

The Atmosphere Special Issue “Lower Atmosphere Meteorology” comprises thirteen original papers dealing with different meteorological processes that occur in the layer of the atmosphere close to the surface and which can greatly affect living beings and materials [...]

Local regressions have been widely employed for decomposing atmospheric data series. However, the use of local quadratic regressions is less extended. The current paper is grounded on the hypothesis that local linear regressions are able to capture CO2 and CH4 temporal evolution equally as well as quadratic linear regressions. Thus, the current pap...

A comparison between monthly CO2 values calculated in the Iberian Peninsula and those measured during six years commencing on October 2010 in the centre of its upper plateau is presented. Gaussian and Epanechnikov kernels are used to calculate CO2 concentration and its growth rate in the study region from values at certain grid points. Slight spati...

Trend analysis requires long-time series of observations, the continuity of which is not usually obtained since gaps emerge linked to problems with the device or external reasons. This paper explores the influence of dataset density on the parameters involved in linear trends of CO2 and CH4 half-hourly observations and daily ranges measured at a se...

This paper is based on CO2 and CH4 semi-hourly mole fraction measurements obtained at the Low Atmosphere Research Centre (CIB) between 2010 and 2016 using a Picarro G1301 analyser. The main aims of the study were to examine the temporal variation of CO2 and CH4 by using six different kernel functions, and to study the suitability of these functions...

The focus of the current paper is to explore the influence of meteorological variables on atmospheric CO 2 and CH 4 mean annual cycles at a rural site. Four variables were investigated: boundary layer height, recirculation factor, trajectory direction, and wind speed modelled at the altitude of the site. Boundary layer height and wind speed were pr...

This work analyses levels of particles PM10 and PM2.5 recorded at four air-quality monitoring stations located in the urban area of Valladolid (Spain) during 2015–2016. To achieve this, the evolution of particle concentrations at different time scales was determined. Average concentrations ranged from 15.3 to 17.6 µg m⁻³ for PM10 and between 8.9 an...

The integrated SCOPE (Soil, Canopy Observation, Photochemistry and Energy balance) model, coupling radiative transfer theory and biochemistry, was applied to a biodiesel crop grown in a Spanish agricultural area. Energy fluxes and CO2 exchange were simulated with this model for the period spanning January 2008 to October 2008. Results were compared...

CO2 and CH4 evolution is usually linked with sources, sinks and their changes. However, this study highlights the role of meteorological variables. It aims to quantify their contribution to the trend of these greenhouse gases and to determine which contribute most. Six years of measurements at a semi-natural site in northern Spain were considered....

This study presents a simpler procedure for grouping air parcel back trajectories than others previously applied. Two-day air parcel back trajectories reaching an unpolluted site in the centre of the northern plateau of the Iberian Peninsula were calculated over a three-year period using the METEX model. A procedure based on the kernel density calc...

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 CO2 and CH4 concentrations. A bivariate smoothin...

The present paper seeks to improve our knowledge concerning the evolution of CO2 and CH4 in terms of monthly trends, growth rate and seasonal variations in the lower atmosphere. Dry continuous measurements of CO2 and the CH4 mixing ratio were carried out over five and a half years (from 15 October 2010 to 29 February 2016) by multi-point sampling a...

The main objective of this paper is to implement different methods to assess the salient features of the data trend for a CO2 and CH4 data series. Said series was obtained at the Low Atmosphere Research Centre (41°48′49″ N, 4°55′59″ W) using a Picarro analyser (G1301). Different functions were employed to determine and quantify the data trend. The...

CO2 and CH4 were recorded from October 2010 to February 2016 with a Picarro G1301 analyser at the centre of the upper plateau of the Iberian Peninsula. Large CO2 values were observed during the vegetation growing season, and were reinforced by the stable boundary layer during the night. Annual CH4 evolution may be explained by ecosystem activity an...

Concentrations of CO2 and CH4 measured over 3 years at a rural site in the Spanish northern plateau were investigated together with vegetation and meteorological variables. Two procedures were implemented to study the annual evolution. Kernel estimation provided a detailed time description, and the harmonic model may be fitted easily. The site was...

Continuous methane (CH4) concentrations were measured in Northern Spain over two years (2011–2012) by multi-point sampling at 1.8, 3.7 and 8.3 m using a Picarro analyser. The technique is based on cavity ring-down spectroscopy. The contrast in mean concentrations was about 1.2 ppb, with 95th percentiles differing by 2.2 ppb and mean minimum concent...

Air masses reaching the Iberian Peninsula, which is located between two continents and two seas, have been classified. 24-h backward air trajectories were calculated each hour for three years using the METEX model at a site in the centre of the northern plateau of the Iberian Peninsula where the air flow has scarcely been investigated to date. Rath...

The influence of airflow on CO2 concentrations is considered. Two years of measurements recorded with a Picarro G1301 analyser during the night at a rural site were used. Three concentration groups were formed and were related to wind speed. Yearly, directional, and hourly evolution indicated that the isolated contribution of factors affecting CO2...

Air trajectory calculations are commonly found in a variety of atmospheric analyses. However, most of reported research usually focuses upon the transport of pollutants via trajectory routes and not on the trajectory itself. This paper explores the major areas of research in which air trajectory analyses are applied with an effort to gain deeper in...

In rural environments, atmospheric CO2 is mainly controlled by natural processes such as respiration-photosynthesis or low atmosphere evolution. This paper considers atmospheric CO2 measurements obtained at a rural site during 2011 using the wavelength-scanned cavity ringdown spectroscopy technique and presents two clustering methods, the silhouett...

This paper investigates patterns of daily evolutions of CO2 in the lower atmosphere at a rural site over 2 years. The first part is devoted to observation analysis using a clustering procedure. However, direct application of the average-linkage method yielded undesirable results. In order to improve this procedure, data were previously processed us...

This paper provides evidence that symmetry of CO2 concentration distribution may indicate sources or dispersive processes. Skewness was calculated by different procedures with CO2 measured at a rural site using a Picarro G1301 analyser over a two-year period. The usual skewness coefficient was considered together with fourteen robust estimators. A...

Continuous methane, CH4, concentrations were measured in a rural area of the upper Spanish plateau from June 2010 to May 2012 by cavity ring-down spectroscopy technique. The results obtained have proven the local impact of anthropogenic nearby sources on CH4 concentrations, and evidence a significant influence on the overall mean, averaged daily an...

CO2 concentrations recorded for two years using a Picarro G1301 analyser at a rural site were studied applying two procedures. Firstly, the smoothing kernel method, which to date has been used with one linear and another circular variable, was used with pairs of circular variables: wind direction, time of day, and time of year, providing that the d...

CO(2) transport in the low atmosphere near the surface at night was analysed using spatial procedures applied to back trajectories. Concentration and meteorological data were obtained at a rural site during a seven and a half month campaign. Daily evolution of CO(2) skewness showed positive values during the night and negative values during the day...

Directional analysis procedures were extended to study the CO(2) daily cycle in the low atmosphere at a rural site. Weighted average, asymmetric circular functions, and conditional probability curves were applied to concentrations recorded at three levels near surface. Wind speed and potential temperature gradient were the meteorological variables...

The impact of CO(2) urban plume in a rural area was investigated by concentrations recorded near surface. CO(2) dry concentrations at three levels near surface were recorded for about 8 months at a rural site. Daily cycles were obtained and directional analysis was made with percentiles. Several functions were used to fit background and plume conce...

El cambio climático es uno de los principales retos ambientales a los que se enfrenta la sociedad actual. Su principal causa es el incremento de emisiones de gases de efecto invernadero a la atmósfera, en especial el dióxido de carbono, CO2. Con el Protocolo de Kioto, los países firmantes se comprometieron a reducir las emisiones a nivel global al...

Integral quantities, wind run, S, and recirculation factor, R, useful for describing air flow, are calculated and combined with CO(2) mixing ratios. Meteorological observations were obtained from a RASS sodar and CO(2) mixing ratios from a continuous analyzer installed at a rural site in the upper Spanish plateau. The measuring campaign spread over...

Conditional probability was used to establish persistence of CO(2) concentrations at a rural site. Measurements extended over three years and were performed with a CO(2) continuous monitor and a sodar. Concentrations in the usual range at this site were proposed as the truncation level to calculate conditional probability, allowing us to determine...

Persistence of CO2 daily means recorded at a rural site over three years was analysed using three procedures: the ST method, rescaled range analysis and detrended fluctuation analysis. Four series were previously considered, since the original series was detrended and gaps were filled. The detrending procedure comprised four steps: a linear evoluti...

Two atmospheric dispersion schemes, the transport index and the Bultynck–Malet scheme, have been analysed and combined by means of a three-year database obtained at a rural site comprising CO2 surface concentrations and meteorological variables (wind and temperature profiles) from a RASS sodar. The most noticeable feature of the transport index is...

Temperature and wind speed profiles obtained from 3years of radio acoustic sounding system sodar measurements at a rural site in the northern Spanish plateau were fitted to polynomial functions. Depending on the extrema of these fits, several groups of profiles were considered. Daily evolution of temperature profiles corresponded to the lower bound...

Measurements of atmospheric carbon dioxide, CO(2), were continuously carried out in the upper Spanish plateau over a three-year campaign, 2003-2005. Temporal CO(2) variations were examined. The results allow identification of the average data representative of background conditions, 382.9 ppm, with values ranging from 346.2 to 502.5 ppm. The weekly...

CO2 in the rural atmosphere is related to respiration–photosynthesis processes, although the evolution of the low atmosphere is also a determinant factor. CO2 concentrations were measured at surface and meteorological variables obtained from a radio acoustic sounding system sodar at a flat rural site during a 3-year campaign. Yearly and daily cycle...

CO2 is one of the most important gases linked to climate change. However, its ambient concentrations in a clean atmosphere have scarcely been investigated. In this paper a close relationship between CO2 concentrations and meteorological variables was proposed to establish atmospheric conditions linked to high CO2 values. A detailed 3-year campaign...

CO(2) 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 CO(2) 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 di...

Continuous carbon dioxide (CO2) measurements over the period 2004-2005 for a rural area in the upper Spanish plateau were examined to characterize the influence of sources and sinks. The diurnal pattern and the annual cycle are presented. The baseline CO2 levels over the time frames researched are determined so as to achieve a more accurate verific...

A vertical description of low atmosphere is essential for air pollution analysis, structural design or wind resource assessment. Measurements of horizontal and vertical wind speed and virtual temperature obtained from a Radio Acoustic Sounding System (RASS) sodar below 200 m during 2 years have been considered in this paper with two objectives: the...

Sodars are useful devices in atmospheric research beyond the first tenths of metres, the management of their observations proving equally important as the data itself. In this paper, a 3-year database of wind direction and speed was used, although in this case both variables have been transformed. The lowest measurement level was considered as a re...

Two analyses have been performed of the use of the Weibull distribution to describe wind speed statistics. The first is a combination of theoretical considerations in a common domain of c and k parameters concerning some robust indicators of position, spread, skewness, and kurtosis. The second is a calculation of the Weibull parameters using three...

Cylindrical models, although scarcely used, are helpful tools in atmospheric science applications such as siting wind machines or setting up atmospheric pollution monitors. In this paper, three simple models have been successfully compared. The first, a second-order model, is an addition of two harmonic functions and was obtained by a multiple line...

Analysis of wind speed and temperature is important to describe momentum and heat exchanges and for wind energy applications. A near 20-month database from a Radio Acoustic Sounding System (RASS) sodar located on a plateau in Northern Spain was used. Autocorrelation functions calculated for wind speed and temperature at 40 and 200 m revealed that o...

Autocorrelation analysis is necessary in persistence studies and identification of cyclical processes. In this paper, autocorrelations of available wind speed and temperature data from a radio acoustic sounding system (RASS) sodar were calculated. This device was placed on flat terrain, and the measuring campaign extended over April 2001. Ten-minut...