Isidro Pérez

Followers

Following

Co-author

Public Views

Interests

Uploads

Papers by Isidro Pérez

Analysis of Ozone Concentrations between 2002–2020 in Urban Air in Northern Spain

Atmosphere

This paper analyses surface ozone measurements at five stations in an urban area (Valladolid) in ... more 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 evolution of ozone at all the stations showed mean maximum concentrations in the afternoon, 15:00 GMT, with values ranging between 73.8 and 80.9 µg m−3, evidencing the influence of photochemical processes favoured by solar radiation in ozone formation. The lowest levels were recorded at night and in the early morning, 7:00 GMT, and were between 23.4 and 32.3 µg m−3, related with the reduction by NO reactions and deposition processes. A broad spring–summer peak between May and July was seen, with the highest values in the latter, with a mean value of up to 73.8 µg m−3. The variation in the monthly mean ozone concentrations of the different perce...

Download

Wind Speed Analysis of Hurricane Sandy

Atmosphere

The database of the HWind project sponsored by the National Oceanic and Atmospheric Administratio... more The database of the HWind project sponsored by the National Oceanic and Atmospheric Administration (NOAA) for hurricanes between 1994 and 2013 is analysed. This is the first objective of the current research. Among these hurricanes, Hurricane Sandy was selected for a detailed study due to the number of files available and its social relevance, with this being the second objective of this study. Robust wind speed statistics showed a sharp increase in wind speed, around 6 m s−1 at the initial stage as Category 1, and a linear progression of its interquartile range, which increased at a rate of 0.54 m s−1 per day. Wind speed distributions were initially right-skewed. However, they evolved to nearly symmetrical or even left-skewed distributions. Robust kurtosis was similar to that of the Gaussian distribution. Due to the noticeable fraction of wind speed intermediate values, the Laplace distribution was used, its scale parameter increasing slightly during the hurricane’s lifecycle. The ...

Download

CO 2 dilution in the lower atmosphere from temperature and wind speed profiles

Theoretical and Applied Climatology

Temperature and wind speed profiles obtained from 3 years of radio acoustic sounding system sodar... more Temperature and wind speed profiles obtained from 3 years 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 boundary layer evolution. However, wind speed profiles revealed a frequent low-level jet during the whole day. CO 2 surface concentrations were analysed, and surface CO 2 dilution was also considered by selection of thin canopies with variable depth, resulting in dilution rates of 7 and 18 ppm when the layer increased 100 m for the 95th percentile and temperature and wind speed profiles, respectively.

Download

Analysis of two atmospheric dispersion schemes from CO2 surface concentrations at a rural site

Quarterly Journal of …, 2011

... Correspondence: Isidro A. Pérez, University of Valladolid c/Prado de la Magdalena s/n 47071 V... more

Autocorrelation analysis of meteorological data from a RASS sodar

Journal of Applied …, 2004

... Corresponding author address: Isidro A. Pérez, Department of Applied Physics, Faculty of Scie... more

Daily and annual cycle of CO 2 concentration near the surface depending on boundary layer structure at a rural site in Spain

Theoretical and Applied …, 2009

... J Atmos Sol-Terr Phys 70:89100 Prabha TV, Venkatesan R, Mursch-Radlgruber E, Rengarajan G, J... more

Statistical Analysis of the CO2 and CH4 Annual Cycle on the Northern Plateau of the Iberian Peninsula

Atmosphere

Outliers are frequent in CO2 and CH4 observations at rural sites. The aim of this paper is to est... more Outliers are frequent in CO2 and CH4 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 in order to suitably describe the annual evolution of both gases. Monthly CO2 and CH4 percentiles were calculated over a six-year period. Linear trends for most of the percentiles were around 2.24 and 0.0097 ppm year−1, and the interquartile ranges of residuals calculated from detrended concentrations were 6 and 0.02 ppm for CO2 and CH4, respectively. Five concentration groups were proposed for CO2 and six were proposed for CH4 from the lag-1 autocorrelation applied to detrended observations. Monthly medians were calculated in each group, and combinations of harmonics were applied in an effort to fit the annual cycle. Finally, adding annual a...

Download

Lower Atmosphere Meteorology

Atmosphere

The Atmosphere Special Issue “Lower Atmosphere Meteorology” comprises thirteen original papers de... more

Download

Analysis of the airflow at the centre of the upper plateau on the Iberian Peninsula and its link to CO2 and CH4 concentrations

International Journal of Climatology

Air trajectories are useful tools to investigate the airflow and transport of substances released... more 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.

Download

CO2 spatio-temporal analysis in the Iberian Peninsula

Science of The Total Environment

Influence of dataset density on CO2 and CH4 trend calculation

Air Quality, Atmosphere & Health

Annual and seasonal cycles of CO2 and CH4 in a Mediterranean Spanish environment using different kernel functions

Stochastic Environmental Research and Risk Assessment

Analysis of PM10 and PM2.5 Concentrations in an Urban Atmosphere in Northern Spain

Archives of Environmental Contamination and Toxicology

This work analyses levels of particles PM10 and PM2.5 recorded at four air-quality monitoring sta... more 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 and 14.8 µg m −3 for PM2.5. The highest monthly means were recorded in autumn and winter. The difference between mean concentrations at weekends and on weekdays for PM10 was around 3 µg m −3 at most of the measuring stations and was 1 µg m −3 for PM2.5. Two concentration peaks were found during the day, one in the morning and the other in the evening, which evidenced the influence of traffic and other anthropogenic activities on PM concentrations. Their mean values were approximately 21 and 17-21 µg m −3 , respectively, for PM10. Mean maximum values for PM2.5 were 12 µg m −3 , except at one of the measuring sites, with 17 µg m −3 for the morning maximum and 1 µg m −3 more for the nocturnal peak. In addition, the impact of longdistance transport of air masses in the study area was analysed by applying a HYSPLIT trajectory model, taking into account backward trajectories of European, African, and Atlantic origins as well as local conditions. In particular, high concentration events due to Saharan dust intrusions are presented. Finally, background levels of particle concentrations estimated at most sampling areas were around 15 and 7.7 µg m −3 for the PM10 and PM2.5 particle fractions, respectively.

Download

SCOPE model applied for rapeseed in Spain

The Science of the total environment, Jan 29, 2018

The integrated SCOPE (Soil, Canopy Observation, Photochemistry and Energy balance) model, couplin... more 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 COexchange were simulated with this model for the period spanning January 2008 to October 2008. Results were compared to experimental measurements performed using eddy covariance and meteorological instrumentation. The reliability of the model was proven by simulating latent (LE) and sensible (H) heat fluxes, soil heat flux (G), and COexchanges (NEE and GPP). LAI data used as input in the model were retrieved from the MODIS and MERIS sensors. SCOPE was able to reproduce similar seasonal trends to those measured for NEE, GPP and LE. When considering H, the modelled values were underestimated for the period covering July 2008 to mid-September 2008. The modelled fluxes reproduced the observed seasonal evolution with determination coefficients of over 0.77 whe...

Download

The influence of meteorological variables on CO2 and CH4 trends recorded at a semi-natural station

Journal of environmental management, Jan 21, 2017

CO2 and CH4 evolution is usually linked with sources, sinks and their changes. However, this stud... more 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. Three sections are established: the first focuses on monthly deciles, the second explores the relationship between pairs of meteorological variables, and the third investigates the relationship between meteorological variables and changes in CO2 and CH4. In the first section, monthly outliers were more marked for CO2 than for CH4. The evolution of monthly deciles was fitted to three simple expressions, linear, quadratic and exponential. The linear and exponential are similar, whereas the quadratic evolution is the most flexible since it provided a variable rate of concentration change and a better fit. With this last evolution, a decrease ...

Download

Wind speed description and power density in northern Spain

Energy

Wind resources are increasingly being investigated as a clean alternative for generating energy. ... more Wind resources are increasingly being investigated as a clean alternative for generating energy. This paper analyses the daily wind speed recorded at 46 automatic weather stations located in Navarre, northern Spain, in 2005e2015. Key points are the surface density of stations and the range of time that ensure a faithful depiction of wind speed together with surface calculations from image analysis and correlation with height. Different statistics were used. Median wind speed at 10 m was low, about 3.3 m s À1 and its interquartile range was narrow, about 2.3 m s À1. Nearly half the surface shows a median wind speed above 3.0 m s À1. The method of moments was employed to calculate the parameters of the Weibull distribution. Around half of the surface presented a shape parameter above 2.25 and the scale parameter was above 4 m s À1 for nearly 41% of the region. Although wind resources are not suitable for wind turbine applications in most of the region, since the wind speed is low in low-lying areas, about 12% of the region is suitable for stand-alone applications and, moreover, a substantial part of the region, around 23%, presents satisfactory wind resources for the installation of wind turbines.

Download

Temporal patterns of CO2 and CH4 in a rural area in northern Spain described by a harmonic equation over 2010-2016

The Science of the total environment, Jan 21, 2017

The present paper seeks to improve our knowledge concerning the evolution of CO2 and CH4 in terms... more 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 at 1.8, 3.7 and 8.3m, using a Picarro analyzer at a rural site in the Low Atmosphere Research Centre (CIBA), on the upper Spanish plateau. Data were divided into diurnal and nocturnal records. The mathematical equation proposed to analyze the overall data was a harmonic one, comprising a polynomial (trend) and a series of harmonics (seasonal cycle). Amplitude was considered as a constant and variable term over time. Quite different behaviour was found between day and night measurements in both climate forcing agents. CO2 showed an accelerating trend in autumn, whereas CH4 trends were higher during the winter. Increasing growth rates were re...

An experimental relationship between airflow and carbon dioxide concentrations at a rural site

Science of The Total Environment, 2015

The influence of airflow on CO2 concentrations is considered. Two years of measurements recorded ... more 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 concentrations proves hard to evaluate. Two approaches to airflow based on average wind and a rotating residual were considered. Around two thirds of observations corresponded to anticyclonic rotations. Firstly, circular hodographs of rotating residuals indicated that wavelengths were in the mesoscale range. The greatest concentrations were linked to the lowest wind speeds and no prevailing directions were revealed by the roundness calculation in a spatial analysis using hexagonal cells. Secondly, composite hodographs for anticyclonic turnings were calculated, the greatest concentrations being associated to hodographs with a pronounced curvature. Moreover, these were successfully parameterised using two models. A harmonic function was first used, which satisfactorily fitted hodographs linked to low and intermediate concentrations. The second model initially described the wind direction of residuals with the error function since its change was slow in early and late night-time. Residuals were later parameterised with a second order logarithmic spiral. This procedure successfully fitted the most curved hodographs of low and high concentrations.

Intercambio Neto De Dióxido De Carbono en Un Ecosistema Rural

ABSTRACT

Daily patterns of CO2 in the lower atmosphere of a rural site

Theoretical and Applied Climatology, 2014

Isidro Pérez

Uploads

Papers by Isidro Pérez

Log In