Suchergebnisse

This study considers the role of distance to the African source on the amount of deposition. To this end, dry and wet deposition was measured at a site close to Africa (Santa Cruz de Tenerife in the Canary Islands, SCO) and at a distant site located in NE Spain (La Castanya, Montseny, MSY). Because of the important influence of African influence on the buildup of particles in the atmosphere, we specifically addressed the contribution of North African events (NAF events) compared to other provenances (no-NAF events) in the wet and dry pathways at the two sites. At the site close to Africa, most of the crustal-derived elements were deposited in the dry mode, with NAF events contributing more than no-NAF events. Marine elements, by contrast, were mostly deposited at this site in the wet form with a predominance of no-NAF events. At MSY, wet deposition of SO4–S, NO3–N and NH4–N during NAF events was higher than at the site close to Africa, either in the wet or dry mode. This fact suggests that mineral dust interacts with pollutants, the mineral surface being coated with ammonium, sulphate and nitrate ions as the dust plume encounters polluted air masses in its way from North Africa to the Western Mediterranean. African dust may provide a mechanism of pollution scavenging and our results indicate that this removal is more effective in the wet mode at sites far away from the mineral source. ; Acknowledge the financial support from the Spanish Government (CGL2005-07543-CLI, CGL2009-13188-C03-01, CSD2008-00040-Consolider Montes grants and the "Subprograma MICINN-PTA" funded by the European Social Fund). The Global Atmospheric Watch program at the Air Quality Research Observatory at Santa Cruz de Tenerife has been funded by AEMET. The IDAEA group acknowledges the financial support of the Generalitat de Catalunya (AGAUR 2014 SGR33 and the DGQA)

The authors wish to thank to different projects and entities for financing this study: COST ES0603 EUPOL; Laboratorios LETI S.A.; Proyecto EOLO-PAT; European Commission for «ENV4-CT98-0755»; Spanish Ministry of Science and Technology I+D+I for «AMB97-0457-CO7-021», «REN2001-10659-CO3-01», «BOS2002-03474», «CGL2004-21166-E», «CGL2005-07543/CLI», «CGL2009-11205» and CONSOLIDER CSD2007_00067 GRACCIE; Andalusian Government for «RNM-5058»; and Catalan Government AGAUR for «2002SGR00059», «2005SGR00519» and «2009SGR1102».

This study simultaneously examines wind speed trends at the land–ocean interface, and below–above the trade-wind inversion layer in the Canary Islands and the surrounding Eastern North Atlantic Ocean: a key region for quantifying the variability of trade-winds and its response to large-scale atmospheric circulation changes. Two homogenized data sources are used: (1) observed wind speed from nine land-based stations (1981–2014), including one mountain weather station (Izaña) located above the trade-wind inversion layer; and (2) simulated wind speed from two atmospheric hindcasts over ocean (i.e., SeaWind I at 30 km for 1948–2014; and SeaWind II at 15 km for 1989–2014). The results revealed a widespread significant negative trend of trade-winds over ocean for 1948–2014, whereas no significant trends were detected for 1989–2014. For this recent period wind speed over land and ocean displayed the same multi-decadal variability and a distinct seasonal trend pattern with a strengthening (late spring and summer; significant in May and August) and weakening (winter–spring–autumn; significant in April and September) of trade-winds. Above the inversion layer at Izaña, we found a predominance of significant positive trends, indicating a decoupled variability and opposite wind speed trends when compared to those reported in boundary layer. The analysis of the Trade Wind Index (TWI), the North Atlantic Oscillation Index (NAOI) and the Eastern Atlantic Index (EAI) demonstrated significant correlations with the wind speed variability, revealing that the correlation patterns of the three indices showed a spatio-temporal complementarity in shaping wind speed trends across the Eastern North Atlantic. ; C. A. -M. has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 703733 (STILLING project). This research was also supported by the Research Projects: Swedish BECC, MERGE, VR (2014–5320), PCIN-2015-220, CGL2014-52135-C03-01 and Red de ...

This paper presents a new empirical equation relating horizontal visibility and PM10 dust concentrations. The new empirical equation (IZO-Eq) is derived from observations performed at the Izaña Atmospheric Observatory (IZO, 28.30ºN, 16.49ºW, 2367 m a.s.l., Tenerife, Spain), recorded during Saharan dust outbreaks from 2003 to 2010. A filter based on relative humidity, present-weather and aerosol optical properties is applied to identify dust events. IZO-Eq is validated in the Sahel region during the dry and wet seasons (2006-2008) using data from two PM10 monitoring stations from the African Monsoon Multidisciplinary Analysis (AMMA) International project, and data from the nearest meteorological synoptic stations. The estimated PM10 derived from IZO-Eq is compared against that those obtained by other empirical equations and dust surface concentrations from NMMB/BSC-Dust model. IZO-Eq presents better performance than the other equations in both dry and wet seasons when compared with observed PM10 at two Sahelian sites. IZO-Eq is also able to reproduce the surface concentration variability simulated by NMMB/BSC-Dust. Above 10 km of horizontal visibility, empirical equations cannot be used to estimate PM10, since above this threshold equations estimate a nearly constant PM10 value, regardless of the visibility range. A comparison between the PM10 spatial distributions derived from visibility SYNOP observations through IZO-Eq, the modelled values from the NMMB/BSC-Dust model and aerosol optical depth (AOD) retrieved from MODIS is performed for the 2006-2008 period. The different spatial distributions present a rather good agreement among them as well as to reproduce the characteristic seasonal dust features over North Africa. ; The present work was carried out in the framework of the Monitoring Atmospheric Composition and Climate (MACC-II) project under the European Union Seventh Research Framework Program (Grant Agreement Number 283576), and as part of the activities of the World Meteorological Organization Sand and ...

Presentación realizada para: XI Congreso de la Asociación Española de Climatología celebrado Cartagena entre el 17 y el 19 de octubre de 2018. ; This research has received funding from the European Union's Horizon 2020 research and innovation programmeunder the Marie Skłodowska-Curie grant agreement No. 703733 (STILLING project).

Comunicación presentada en: 2012 European Aerosol Conference (EAC-2012), B-WG01S2P30, celebrada del 2 al 7 de septiembre de 2012 en Granada. ; This work has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement N. 262254. Financial support from the Spanish Ministry of Science (MICINN) under projects with ref. CGL2009-09740, CGL2011-23413, CGL2010-09480-E and CGL2011-13085-E as well as from Junta de Castilla y León are gratefully acknowledged.

This work involves a first analysis of the systematic errors observed in the AOD retrieved at nighttime using the Sun–sky–lunar CE318-T photometer. In this respect, this paper is a first attempt to correct the AOD uncertainties that currently affect the lunar photometry by means of an empirical regression model. We have detected and corrected an important bias correlated to the Moon's phase and zenith angles, especially at longer wavelength channels. ; AERONET Sun photometers at Izaña have been calibrated within the AERONET Europe TNA, supported by the European Union's Horizon 2020 research and innovation program under grant agreement no. 654109 (ACTRIS-2).

A 7-year comparison study between measured and simulated LDR under cloud-free conditions has been performed at the BSRN Izaña. Results show an excellent agreement with a mean bias (simulated-measured) < 1.1 %, and RMSE < 1 %, are within the instrumental error (2 %). ; AERONET Sun photometers at Izaña have been calibrated within the AERONET Europe TNA, supported by the European Union's Horizon 2020 research and innovation program under grant agreement no. 654109 (ACTRIS-2). This research has benefited from the result of the project INMENSE (funded by the Ministerio de Economía y Competividad from Spain, CGL2016-8068.

A 7-year (2010–2016) comparison study between measured and simulated longwave downward radiation (LDR) under cloud-free conditions was performed at the Izaña Atmospheric Observatory (IZO, Spain). This analysis encompasses a total of 2062 cases distributed approximately evenly between day and night. Results show an excellent agreement between Baseline Surface Radiation Network (BSRN) measurements and simulations with libRadtran V2.0.1 and MODerate resolution atmospheric TRANsmission model (MODTRAN) V6 radiative transfer models (RTMs). Mean bias (simulated - measured) of 10 mm, the observed night-time difference between models and measurements is +5Wm-2 indicating a scale change of the World Infrared Standard Group of Pyrgeometers (WISG), which serves as reference for atmospheric longwave radiation measurements. Preliminary results suggest a possible impact of dust aerosol on infrared radiation during daytime that might not be correctly parametrized by the models, resulting in a slight underestimation of the modeled LDR, of about -3Wm-2, for relatively high aerosol optical depth (AOD>0.20). ; AERONET Sun photometers at Izaña have been calibrated within the AERONET Europe TNA, supported by the European Union's Horizon 2020 research and innovation program under grant agreement no. 654109 (ACTRIS-2). This research has benefited from the result of the project INMENSE (funded by the Ministerio de Economía y Competividad from Spain, CGL2016-8068.

This manuscript proposes and validates a methodology for the quantification of the daily African PM load during dust outbreaks in southern Europe. The daily net dust load in PM10 attributable to an African episode can be obtained by subtracting the daily regional background (RB) level from the PM10 concentration value at a RB station. The daily RB level can be obtained by applying a monthly moving 30th percentile to the PM10 time series at a RB station after a prior extraction of the data coincident with African dust transport. For days with influence of African dust, the dust load is given by the difference between the daily PM10 values minus the daily PM10 RB levels. This method allows us to quantify the net African dust load without chemical speciation. The comparison between the estimated net load during African dust outbreaks (ADO) and the crustal load determined by chemical speciation of PM10 filters at three RB stations in Spain had resulted in a very good correlation (R2=0.60-0.83), being the equivalence (correlation lines' slopes ~ 1) highly significant in the three cases. ; This study was supported by the S.G.D. Environmental Quality and Industrial Environment from the Spanish Ministry of the Environment, but also by research projects from the Ministry of Science and Innovation (CGL2005-03428- C04-03/CLI, CGL2007-62505/CLI, GRACCIE- CSD2007-00067), the European Union (6th framework CIRCE IP, 036961, EUSAAR RII3-CT-2006-026140) and the Ministry of the Environment (CALIOPE, 441/2006/3-12.1).

The aim of this paper is to analyze the suitability of the high-mountain stations Mauna Loa and Izaña for Langley plot calibration of Sun photometers. Thus the aerosol optical depth (AOD) characteristics and seasonality, as well as the cloudiness, have been investigated in order to provide a robust estimation of the calibration uncertainty as well as the number of days that are suitable for Langley calibrations. The data used for the investigations belong to the AERONET and GAW-PFR networks, which maintain reference Sun photometers at these stations with long measurement records: 22 years at Mauna Loa and 15 years at Izaña. In terms of clear-sky and stable aerosol conditions, Mauna Loa (3397ma.s.l.) exhibits on average 377 Langley plots (243 morning and 134 afternoon) per year suitable for Langley plot calibration, whereas Izaña (2373ma.s.l.) shows 343 Langley plots (187 morning and 155 afternoon) per year. The background AOD (500nm) values, on days that are favorable for Langley calibrations, are in the range 0.01–0.02 throughout the year, with well-defined seasonality that exhibits a spring maximum at both stations plus a slight summer increase at Izaña. The statistical analysis of the long-term determination of extraterrestrial signals yields to a calibration uncertainty of ∼ 0.25–0.5%, this uncertainty being smaller in the visible and near-infrared wavelengths and larger in the ultraviolet wavelengths. This is due to atmospheric variability produced by changes in several factors, mainly the AOD. The uncertainty cannot be reduced based only on quality criteria of individual Langley plots and averaging over several days is shown to reduce the uncertainty to the needed levels for reference Sun photometers. ; This research has received funding from the European Union's Horizon 2020 Research and Innovation Programme under grant agreement no. 654109 (ACTRIS-2). The funding by MINECO (CTM2015-66742-R) and Junta de Castilla y León (VA100P17) is also acknowledged.

In the present work, atmospheric mineral dust from a MACC-II short reanalysis run for 2 years (2007–2008) has been evaluated over northern Africa and the Middle East using satellite aerosol products (from MISR, MODIS and OMI satellite sensors), ground-based AERONET data, in situ PM10 concentrations from AMMA, and extinction vertical profiles from two ground-based lidars and CALIOP satellite-based lidar. The MACC-II aerosol optical depth (AOD) spatial and temporal (seasonal and interannual) variability shows good agreement with those provided by satellite sensors. The capability of the model to reproduce the AOD, Ångström exponent (AE) and dust optical depth (DOD) from daily to seasonal time-scale is quantified over 26 AERONET stations located in eight geographically distinct regions by using statistical parameters. Overall DOD seasonal variation is fairly well simulated by MACC-II in all regions, although the correlation is significantly higher in dust transport regions than in dust source regions. The ability of MACC-II in reproducing dust vertical profiles has been assessed by comparing seasonal averaged extinction vertical profiles simulated by MACC-II under dust conditions with corresponding extinction profiles obtained with lidar instruments at M'Bour and Santa Cruz de Tenerife, and with CALIOP. ; This work has been supported by EU-project Monitoring Atmospheric Composition and Climate (MACC-II) under the European Union Seventh Framework Programme, grant agreement number 283576. J. M. Baldasano and S. Basart acknowledge the Severo Ochoa (SEV-2011-00067) program of the Spanish Government and the mobility program from the Catalan Government (BE-DGR 2012).

In the present work, atmospheric mineral dust from a MACC-II short reanalysis run for 2 years (2007–2008) has been evaluated over northern Africa and the Middle East using satellite aerosol products (from MISR, MODIS and OMI satellite sensors), ground-based AERONET data, in situ PM10 concentrations from AMMA, and extinction vertical profiles from two ground-based lidars and CALIOP satellite-based lidar. The MACC-II aerosol optical depth (AOD) spatial and temporal (seasonal and interannual) variability shows good agreement with those provided by satellite sensors. The capability of the model to reproduce the AOD, Ångström exponent (AE) and dust optical depth (DOD) from daily to seasonal time-scale is quantified over 26 AERONET stations located in eight geographically distinct regions by using statistical parameters. Overall DOD seasonal variation is fairly well simulated by MACC-II in all regions, although the correlation is significantly higher in dust transport regions than in dust source regions. The ability of MACC-II in reproducing dust vertical profiles has been assessed by comparing seasonal averaged extinction vertical profiles simulated by MACC-II under dust conditions with corresponding extinction profiles obtained with lidar instruments at M'Bour and Santa Cruz de Tenerife, and with CALIOP. ; This work has been supported by EU-project Monitoring Atmospheric Composition and Climate (MACC-II) under the European Union Seventh Framework Programme, grant agreement number 283576. J. M. Baldasano and S. Basart acknowledge the Severo Ochoa (SEV-2011-00067) program of the Spanish Government and the mobility program from the Catalan Government (BE-DGR 2012).

The synergetic use of meteorological information, remote sensing both ground-based active (lidar) and passive (sun-photometry) techniques together with backtrajectory analysis and in-situ measurements is devoted to the characterization of dust intrusions. A case study of air masses advected from the Saharan region to the Canary Islands and the Iberian Peninsula, located relatively close and far away from the dust sources, respectively, was considered for this purpose. The observations were performed over three Spanish geographically strategic stations within the dust-influenced area along a common dust plume pathway monitored from 11 to 19 of March 2008. A 4-day long dust event (13–16 March) over the Santa Cruz de Tenerife Observatory (SCO), and a linked short 1-day dust episode (14 March) in the Southern Iberian Peninsula over the Atmospheric Sounding Station "El Arenosillo" (ARN) and the Granada station (GRA) were detected. ; This work has been supported by the Spanish Ministry for Science and Innovation (MICINN) under the Complementary Actions CGL2008-01330-E (2009) in the frame of the Spanish and Portuguese Aerosol LIdar NETwork (SPALINET), and CGL2010-10012-E (Evaluation of lidar observations in the frame of CIEMAT/EARLINET intercomparison by airborne in-situ measurements of trace gases and aerosols, MISPA-LIDAR, 2010); projects CGL2008-05939-C03-03/CLI, CGL2007-66477-C02-01, CSD2007-00067 and CGL2010-18782 of the Spanish Ministry of Education; projects P08-RNM-3568 and P10-RNM-6299 of the Autonomous Government of Andalusia; and the EARLINET-ASOS project (EU Coordination Action, contract no. 025991 (RICA)). JLG-R thanks the Spanish Ministry of Education and the Portuguese Fundaçao para a Ciencia e a Tecnologia for supporting under grants EX2009-0700 and SFRH/BPD/63090/2009, respectively.

This paper presents the new photometer CE318-T, able to perform daytime and night-time photometric measurements using the sun and the moon as light source. Therefore, this new device permits a complete cycle of diurnal aerosol and water vapour measurements valuable to enhance atmospheric monitoring to be extracted. In this study we have found significantly higher precision of triplets when comparing the CE318-T master instrument and the Cimel AErosol RObotic NETwork (AERONET) master (CE318-AERONET) triplets as a result of the new CE318-T tracking system. Regarding the instrument calibration, two new methodologies to transfer the calibration from a reference instrument using only daytime measurements (Sun Ratio and Sun-Moon gain factor techniques) are presented and discussed. ; The AERONET sun photometers at Izaña have been calibrated within the AERONETEurope TNA, supported by the European Community-Research Infrastructure Action under the FP7 ACTRIS grant agreement no. 262254. This work has also been supported by the Andalusia regional government through projects P12-RNM-2409 and P10-RNM-6299, by the Spanish Ministry of Science and Technology through project CGL2013-45410-R; and finally by the EU through ACTRIS project (EU INFRA-2010-1.1.16-262254).