Andalusian Institute for Earth System Research IISTA CEAMA

Granada, Spain

Andalusian Institute for Earth System Research IISTA CEAMA

Granada, Spain
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Valenzuela A.,University of Évora | Valenzuela A.,University of Granada | Valenzuela A.,Andalusian Institute for Earth System Research IISTA CEAMA | Arola A.,Finnish Meteorological Institute | And 4 more authors.
Atmospheric Research | Year: 2017

This paper provides an account of observed variations in Black carbon (BC) aerosol concentrations and their induced radiative forcing for the first time over Granada a measurement site in Southeastern Iberian Peninsula. Column-integrated BC concentrations were retrieved for the period 2005–2012. Monthly averages of BC concentrations (± one standard deviation) ranged from higher values in January and December with 4.0 ± 2.5 and 4 ± 3 mg/m2, respectively, to lower values in July and August with 1.6 ± 1.2 and 2.0 ± 0.5 mg/m2, respectively. This reduction is not only observed in the average values, but also in the median, third and first quartiles. The average BC concentration in winter (3.8 ± 0.6 mg/m2) was substantially higher than in summer (1.9 ± 0.3 mg/m2), being the eight-year average of 2.9 ± 0.9 mg/m2. The reduction in the use of fossil fuels during the economic crisis contributed significantly to reduced atmospheric loadings of BC. According to our analysis this situation persisted until 2010. BC concentration values were analyzed in terms of air mass influence using cluster analysis. BC concentrations for cluster 1 (local and regional areas) showed high correlations with air masses frequency in winter and autumn. In these seasons BC sources were related to the intense road traffic and increased BC emissions from domestic heating. High BC concentrations were found in autumn just when air mass frequencies for cluster 3 (Mediterranean region) were more elevated, suggesting that air masses coming from that area transport biomass burning particles towards Granada. BC aerosol optical properties were retrieved from BC fraction using aerosol AERONET size volume distribution and Mie theory. A radiative transfer model (SBDART) was used to estimate the aerosol radiative forcing separately for composite aerosol (total aerosols) and exclusively for BC aerosols. The mean radiative forcing for composite aerosol was + 23 ± 6 W/m2(heating rate of + 0.21 ± 0.06 K/day) and + 15 ± 6 W/m2for BC aerosol (heating rate of + 0.15 ± 0.06 K/day). These values of radiative forcing and heating rate for BC aerosol represent about 70% of their values for composite aerosol, which highlights the crucial role that BC aerosols play in modifying the radiation budget and climate. © 2017

Ortiz-Amezcua P.,Andalusian Institute for Earth System Research IISTA CEAMA | Ortiz-Amezcua P.,University of Granada | Luis Guerrero-Rascado J.,Andalusian Institute for Earth System Research IISTA CEAMA | Luis Guerrero-Rascado J.,University of Granada | And 12 more authors.
Atmospheric Chemistry and Physics | Year: 2017

Strong events of long-range transported biomass burning aerosol were detected during July 2013 at three EARLINET (European Aerosol Research Lidar Network) stations, namely Granada (Spain), Leipzig (Germany) and Warsaw (Poland). Satellite observations from MODIS (Moderate Resolution Imaging Spectroradiometer) and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) instruments, as well as modeling tools such as HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) and NAAPS (Navy Aerosol Analysis and Prediction System), have been used to estimate the sources and transport paths of those North American forest fire smoke particles. A multiwavelength Raman lidar technique was applied to obtain vertically resolved particle optical properties, and further inversion of those properties with a regularization algorithm allowed for retrieving microphysical information on the studied particles. The results highlight the presence of smoke layers of 1-2 km thickness, located at about 5 km a.s.l. altitude over Granada and Leipzig and around 2.5 km a.s.l. at Warsaw. These layers were intense, as they accounted for more than 30 % of the total AOD (aerosol optical depth) in all cases, and presented optical and microphysical features typical for different aging degrees: Color ratio of lidar ratios (LR532/LR355) around 2, α-related ängström exponents of less than 1, effective radii of 0.3 μm and large values of single scattering albedos (SSA), nearly spectrally independent. The intensive microphysical properties were compared with columnar retrievals form co-located AERONET (Aerosol Robotic Network) stations. The intensity of the layers was also characterized in terms of particle volume concentration, and then an experimental relationship between this magnitude and the particle extinction coefficient was established. © 2017 Author(s).

Bravo-Aranda J.A.,Andalusian Institute for Earth System Research IISTA CEAMA | Bravo-Aranda J.A.,University of Granada | Bravo-Aranda J.A.,Ecole Polytechnique - Palaiseau | De Arruda Moreira G.,Brazilian Nuclear Energy Research Institute (IPEN) | And 13 more authors.
Atmospheric Chemistry and Physics | Year: 2017

The automatic and non-supervised detection of the planetary boundary layer height (zPBL) by means of lidar measurements was widely investigated during the last several years. Despite considerable advances, the experimental detection still presents difficulties such as advected aerosol layers coupled to the planetary boundary layer (PBL) which usually produces an overestimation of the zPBL. To improve the detection of the zPBL in these complex atmospheric situations, we present a new algorithm, called POLARIS (PBL height estimation based on lidar depolarisation). POLARIS applies the wavelet covariance transform (WCT) to the range-corrected signal (RCS) and to the perpendicular-to-parallel signal ratio (δ) profiles. Different candidates for zPBL are chosen and the selection is done based on the WCT applied to the RCS and δ. We use two ChArMEx (Chemistry-Aerosol Mediterranean Experiment) campaigns with lidar and microwave radiometer (MWR) measurements, conducted in 2012 and 2013, for the POLARIS' adjustment and validation. POLARIS improves the zPBL detection compared to previous methods based on lidar measurements, especially when an aerosol layer is coupled to the PBL. We also compare the zPBL provided by the Weather Research and Forecasting (WRF) numerical weather prediction (NWP) model with respect to the zPBL determined with POLARIS and the MWR under Saharan dust events. WRF underestimates the zPBL during daytime but agrees with the MWR during night-time. The zPBL provided by WRF shows a better temporal evolution compared to the MWR during daytime than during night-time. © Author(s) 2017.

Anton M.,University of Extremadura | Valenzuela A.,University of Granada | Valenzuela A.,Andalusian Institute for Earth System Research IISTA CEAMA | Mateos D.,University of Valladolid | And 7 more authors.
Atmospheric Research | Year: 2014

This paper analyzes the influence of a strong Saharan dust event on longwave (LW) irradiance recorded at Granada (Southeastern Spain) on 6 September 2007. A detailed comparison with shortwave (SW) radiative effects for the same dust event is also shown. For these goals, simultaneous measurements of LW and SW irradiance were used together with the aerosol optical depth at 675nm (AOD675) derived from a Cimel CE-318 sun-photometer. LW irradiance on 6 September (AOD675 ranged between 0.8 and 1.5) increased 8.4% on average compared to a no-dust day (4 September, AOD675 below 0.15), while the SW irradiance was notably reduced about 28.2%. The study also showed that an increase of one unit in the AOD675 led to an increase (decrease) of LW (SW) irradiance of 20 (187) W/m2. Hence, the LW contribution to offset partially the large SW decrease at surface strongly depends on the aerosol load, changing from 40% for AOD675~0.8 to 20% for AOD675~1.5. On daily average, LW radiative effect was about 39% of the SW one and, therefore, the intense decrease of SW irradiance due to dust particles was substantially offset by the increase of the LW irradiance. © 2014 Elsevier B.V.

Sicard M.,Polytechnic University of Catalonia | Barragan R.,Polytechnic University of Catalonia | Dulac F.,French Climate and Environment Sciences Laboratory | Alados-Arboledas L.,University of Granada | And 2 more authors.
Atmospheric Chemistry and Physics | Year: 2016

In the framework of the ChArMEx (the Chemistry-Aerosol Mediterranean Experiment; program, the seasonal variability of the aerosol optical, microphysical and radiative properties derived from AERONET (Aerosol Robotic Network; is examined in two regional background insular sites in the western Mediterranean Basin: Ersa (Corsica Island, France) and Palma de Mallorca (Mallorca Island, Spain). A third site, Alborán (Alborán Island, Spain), with only a few months of data is considered for examining possible northeast-southwest (NE-SW) gradients of the aforementioned aerosol properties. The AERONET dataset is exclusively composed of level 2.0 inversion products available during the 5-year period 2011-2015. AERONET solar radiative fluxes are compared with groundand satellite-based flux measurements. To the best of our knowledge this is the first time that AERONET fluxes are compared with measurements at the top of the atmosphere. Strong events (with an aerosol optical depth at 440 nm greater than 0.4) of long-range transport aerosols, one of the main drivers of the observed annual cycles and NE-SW gradients, are (1) mineral dust outbreaks predominant in spring and summer in the north and in summer in the south and (2) European pollution episodes predominant in autumn. A NE-SW gradient exists in the western Mediterranean Basin for the aerosol optical depth and especially its coarse-mode fraction, which all together produces a similar gradient for the aerosol direct radiative forcing. The aerosol fine mode is rather homogeneously distributed. Absorption properties are quite variable because of the many and different sources of anthropogenic particles in and around the western Mediterranean Basin: North African and European urban areas, the Iberian and Italian peninsulas, most forest fires and ship emissions. As a result, the aerosol direct forcing efficiency, more dependent to absorption than the absolute forcing, has no marked gradient. © Author(s) 2016.

Mandija F.,University of Shkodra | Mandija F.,Andalusian Institute for Earth System Research IISTA CEAMA | Guerrero-Rascado J.L.,Andalusian Institute for Earth System Research IISTA CEAMA | Guerrero-Rascado J.L.,University of Granada | And 6 more authors.
Atmospheric Environment | Year: 2016

In this paper, we present a study of the columnar and vertically resolved aerosol optical properties over Granada (Spain) during dust events detected during July-August in the period 2012–2013. For this purpose, we classified the events according to their origins and pathways. The analyzed aerosol properties include; columnar aerosol optical properties like aerosol optical depth (AOD) and Angstrom exponent (AE), as well as the lidar products, like backscatter-related Angstrom exponent and linear particle depolarization ratio (LDPR). The lidar profiles are used for determination of the geometrical structure of dust layers and the aerosol optical parameters inside dust layers. There are identified 58 dusty days over Granada during the periods July-August, 2012–2013. In 71% of the dust, event analyzed the dust plume over Granada is located between 3000 and 4000 m a.g.l. Mean values of AOD500 according to the Atlantic and Mediterranean pathway were 0.28 ± 0.10 and 0.93 ± 0.17. Meanwhile, the mean values of AE440-870 were 0.57 ± 0.25 and 0.43 ± 0.20. Three region are identified as the main dust sources affecting the dust intrusions over Granada. Two principal pathways of air masses during dust intrusion over Granada were observed: through Atlantic (52.7%) and through Mediterranean (47.3%). Air masses which come through the Mediterranean present larger AOD and lower Angstrom exponent values than those air masses coming through Atlantic. Lidar measurements show different vertical distributions on particle backscatter coefficient, during different scenarios of dust intrusions. The lidar profiles indicate that average base and top heights of all dust during the investigation period were 2.1 ± 0.7 and 4.8 ± 0.9 km, and their center of mass and thickness were 3.3 ± 0.7 and 2.8 ± 1.0 km a.g.l. The AE355/532 profiles for the dust intrusions present some differences depending on the source regions and path followed by the dust. On the other hand, the profiles of LPDRat 532 nm were more similar for all scenarios. © 2016 Elsevier Ltd

Lyamani H.,Andalusian Institute for Earth System Research IISTA CEAMA | Lyamani H.,University of Granada | Valenzuela A.,Andalusian Institute for Earth System Research IISTA CEAMA | Valenzuela A.,University of Granada | And 9 more authors.
Atmospheric Chemistry and Physics | Year: 2015

This study focuses on the analysis of Aerosol Robotic Network (AERONET) aerosol data obtained over Alborán Island (35.90° N, 3.03° W, 15 m a.s.l.) in the western Mediterranean from July 2011 to January 2012. Additional aerosol data from the three nearest AERONET stations (Málaga, Oujda and Palma de Mallorca) and the Maritime Aerosol Network (MAN) were also analyzed in order to investigate the temporal and spatial variations of aerosol over this scarcely explored region. High aerosol loads over Alborán were mainly associated with desert dust transport from North Africa and occasional advection of anthropogenic fine particles from central European urban-industrial areas. The fine particle load observed over Alborán was surprisingly similar to that obtained over the other three nearest AERONET stations, suggesting homogeneous spatial distribution of fine particle loads over the four studied sites in spite of the large differences in local sources. The results from MAN acquired over the Mediterranean Sea, Black Sea and Atlantic Ocean from July to November 2011 revealed a pronounced predominance of fine particles during the cruise period. © Author(s) 2015.

Granados-Munoz M.J.,University of Granada | Granados-Munoz M.J.,Andalusian Institute for Earth System Research IISTA CEAMA | Navas-Guzman F.,University of Granada | Navas-Guzman F.,Andalusian Institute for Earth System Research IISTA CEAMA | And 15 more authors.
Atmospheric Measurement Techniques | Year: 2015

A new methodology based on combining active and passive remote sensing and simultaneous and collocated radiosounding data to study the aerosol hygroscopic growth effects on the particle optical and microphysical properties is presented. The identification of hygroscopic growth situations combines the analysis of multispectral aerosol particle backscatter coefficient and particle linear depolarization ratio with thermodynamic profiling of the atmospheric column. We analyzed the hygroscopic growth effects on aerosol properties, namely the aerosol particle backscatter coefficient and the volume concentration profiles, using data gathered at Granada EARLINET station. Two study cases, corresponding to different aerosol loads and different aerosol types, are used for illustrating the potential of this methodology. Values of the aerosol particle backscatter coefficient enhancement factors range from 2.1 ± 0.8 to 3.9 ± 1.5, in the ranges of relative humidity 60-90 and 40-83%, being similar to those previously reported in the literature. Differences in the enhancement factor are directly linked to the composition of the atmospheric aerosol. The largest value of the aerosol particle backscatter coefficient enhancement factor corresponds to the presence of sulphate and marine particles that are more affected by hygroscopic growth. On the contrary, the lowest value of the enhancement factor corresponds to an aerosol mixture containing sulphates and slight traces of mineral dust. The Hänel parameterization is applied to these case studies, obtaining results within the range of values reported in previous studies, with values of the γ exponent of 0.56 ± 0.01 (for anthropogenic particles slightly influenced by mineral dust) and 1.07 ± 0.01 (for the situation dominated by anthropogenic particles), showing the convenience of this remote sensing approach for the study of hygroscopic effects of the atmospheric aerosol under ambient unperturbed conditions. For the first time, the retrieval of the volume concentration profiles for these cases using the Lidar Radiometer Inversion Code (LIRIC) allows us to analyze the aerosol hygroscopic growth effects on aerosol volume concentration, observing a stronger increase of the fine mode volume concentration with increasing relative humidity. © Author(s) 2015.

Granados-Munoz M.J.,University of Granada | Granados-Munoz M.J.,Andalusian Institute for Earth System Research IISTA CEAMA | Guerrero-Rascado J.L.,University of Granada | Guerrero-Rascado J.L.,Andalusian Institute for Earth System Research IISTA CEAMA | And 16 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2014

LIRIC (Lidar-Radiometer Inversion Code) is applied to combined lidar and Sun photometer data from Granada station corresponding to different case studies. The main aim of this analysis is to evaluate the stability of LIRIC output volume concentration profiles for different aerosol types, loadings, and vertical distributions of the atmospheric aerosols. For this purpose, in a first part, three case studies corresponding to different atmospheric situations are analyzed to study the influence of the user-defined input parameters in LIRIC when varied in a reasonable range. Results evidence the capabilities of LIRIC to retrieve vertical profiles of microphysical properties during daytime by the combination of the lidar and the Sun photometer systems in an automatic and self-consistent way. However, spurious values may be obtained in the lidar incomplete overlap region depending on the structure of the aerosol layers. In a second part, the use of a second Sun photometer located in Cerro Poyos, in the same atmospheric column as Granada but at higher altitude, allowed us to obtain LIRIC retrievals from two different altitudes with independent Sun photometer measurements in order to check the self-consistency and robustness of the method. Retrievals at both levels are compared, providing a very good agreement (differences below 5-μm3/cm3) in those cases with the same aerosol type in the whole atmospheric column. However, some assumptions such as the height independency of parameters (sphericity, size distribution, or refractive index, among others) need to be carefully reviewed for those cases with the presence of aerosol layers corresponding to different types of atmospheric aerosols. Key Points Microphysical properties are retrieved with LIRIC from lidar and Sun photometer Uncertainties of LIRIC algorithm are evaluated for different conditions A unique set up with two Sun photometers at two altitude levels is used. © 2014. American Geophysical Union. All Rights Reserved.

Nepomuceno Pereira S.,Evora Geophysics Center | Nepomuceno Pereira S.,Andalusian Institute for Earth System Research IISTA CEAMA | Wagner F.,Evora Geophysics Center | Wagner F.,Hohenpeissenberg Meteorological Observatory | Silva A.M.,Evora Geophysics Center
Advances in Meteorology | Year: 2014

Measurements of the aerosol absorption coefficient, between 2007 and 2013, were made at the ground level in Évora, a Portuguese small town located in the southwestern Iberia Peninsula. Such a relatively long time series of absorbing aerosols is unique in Portugal and uncommon elsewhere. The average aerosol absorption coefficient was close to 9 Mm-1 and clear cycles at both daily and seasonal time scales were found. An average increase by a factor of two (from 6 to 12 Mm-1) was observed in winter if compared to summer season. The daily variations were similarly shaped for all seasons, with two morning and afternoon peaks, but with magnitudes modulated by the seasonal evolution. That was not the case if Sundays were considered. These variations can be explained in terms of the impact of local particle sources, related mainly to traffic and biomass burning and upward mixing of the aerosol due to variable mixing layer heights, either daily or seasonally. Also, a strong negative correlation between the aerosol absorption coefficient and the wind speed was verified, and an exponential decay function was found to fit very well to the data. The wind direction seems to be not correlated with the aerosol absorption coefficient. © 2014 Sérgio Nepomuceno Pereira et al.

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