Editorial for the special issue “Remote sensing of atmospheric components and water vapor”

Producción CientíficaThe observation/monitoring of atmospheric components and water vapor in the atmosphere is today open to very different remote sensing techniques, most of them based on the radiation-matter interaction covering the full electromagnetic spectrum. This SI collects some papers regarding the retrieval, calibration, validation, analysis of data and uncertainties, as well as comparative studies on atmospheric gases and water vapor by remote sensing techniques, where different types of sensors, instruments, and algorithms are used or developedMinisterio de Ciencia, Innovación y Universidades (RTI2018-097864-B-I00)Junta de Extremadura - FEDER (IB18092

Evaluation of Water Vapor Radiative Effects Using GPS Data Series over Southwestern Europe

Producción CientíficaWater vapor radiative effects (WVRE) at surface in the long-wave (LW) and short-wave (SW) spectral ranges under cloud and aerosol free conditions are analyzed for seven stations in Spain over the 2007–2015 period. WVRE is calculated as the difference between the net flux obtained by two radiative transfer simulations; one with water vapor from Global Positioning System (GPS) measurements and the other one without any water vapor (dry atmosphere). The WVRE in the LW ranges from 107.9Wm2 to 296.7Wm−2 , while in the SW it goes from −64.9Wm−2 to −6.0Wm−2 . The results show a clear seasonal cycle, which allows the classification of stations in three sub-regions. In general, for total (SW + LW) and LW WVRE, winter (DJF) and spring (MAM) values are lower than summer (JJA) and autumn (SON). However, in the case of SW WVRE, the weaker values are in winter and autumn, and the stronger ones in summer and spring. Positive trends for LW (and total) WVRE may partially explain the well-known increase of surface air temperatures in the study region. Additionally, negative trends for SW WVRE are especially remarkable, since they represent about a quarter of the contribution of aerosols to the strong brightening effect (increase of the SW radiation flux at surface associated with a reduction of the cloud cover and aerosol load) observed since the 2000s in the Iberian Peninsula, but with opposite sign, so it is suggested that water vapor could be partially masking the full magnitude of this brightening.Ministerio de Economía, Industria y Competitividad (grant CGL2017-87917-P)Junta de Extremadura - Fondo Europeo de Desarrollo Regional (grant IB18092)Ministerio de Ciencia, Innovación y Universidades (project RTI2018-097864-B-I00 and fellowship RYC-2016–20784)Junta de Extremadura - Fondo Social Europeo (fellowship PD18029

Aerosol properties of mineral dust and its mixtures in a regional background of north-central Iberian Peninsula

Producción CientíficaTo broaden the knowledge about desert dust (DD) aerosols in western Mediterranean Basin, their fingerprints on optical and microphysical properties are analyzed during DD episodes in the north-central plateau of the Iberian Peninsula between 2003 and 2014. Aerosol columnar properties obtained from the AErosol RObotic NETwork (AERONET), such as aerosol optical depth (AOD), Ångström exponent (AE), volume particle size distribution, volume concentration (VC), sphericity, single scattering albedo, among others, are analyzed in order to provide a general characterization, being some of them compared to particle mass surface concentrations PM10, PM2.5, and their ratio, data obtained from EMEP network. The mean intensity of DD episodes exhibits: AOD440nm = 0.27±0.12, PM10 = 24±18 μg/m3, AE=0.94±0.40 and PM2.5/PM10=0.54±0.16. The AOD and PM10 annual cycles show maximum intensity in March and summer and minima in winter. A customized threshold of AE=1 distinguishes two types of dusty days, those with a prevailing desert character and those of mixed type, which is corroborated by sphericity values. Three well established intervals are obtained with the fine mode volume fraction (VCF/VCT). Coarse-mode-dominated cases (VCF/VCT ≤ 0.2) present a mineral dust character: e.g., particle maximum concentration about 2 μm, non-sphericity, stronger absorption power at shorter wavelengths, among others. The relevance of the fine mode is noticeable in mixtures with a predominance of particles about 0.2-0.3 μm radii. Conditions characterized by 0.2 < VCF/VCT < 0.45 and VCF/VCT ≥ 0.45 present a larger variability in all investigated aerosol properties. Relationships between AOD and columnar particle volume concentration give volume extinction efficiencies between 1.7 and 3.7 μm2/μm3 depending on VCF/VCT. Aerosol scale height is obtained from relationships between surface and columnar concentrations displaying very large values up to 10 km. The uncertainty associated with the transformation between AOD and PM10 can be partially reduced when the aerosol microphysical properties are known.The authors are grateful to Spanish MINECO for the financial support of the FPI grant BES-2012-051868, project CGL2012-33576, and “Juan de la Cierva - Incorporación” grant IJCI-2014-19477. The research leading to these results has received funding from the European Union under grant agreement Nr. 654109 [ACTRIS 2]

Long-term comparative study of columnar and surface mass concentration aerosol properties in a background environment

Producción CientíficaThe relationship between columnar and surface aerosol properties is not a straightforward problem. The Aerosol Optical Depth (AOD), Ångström exponent (AE), and ground-level Particulate Matter (PMX, x=10 or 2.5 µm) data have been studied from a climatological point of view. Despite the different meanings of AOD and PMx both are key and complementary quantities that quantify aerosol load in the atmosphere and many studies intend to find specific relationships between them. Related parameters such as AE and PM ratio (PR=PM2.5/ PM10), giving information about the predominant particle size, are included in this study on the relationships between columnar and surface aerosol parameters. This study is based on long measurement records (2003–2014) obtained at two nearby background sites from the AERONET and EMEP networks in the north-central area of Spain. The climatological annual cycle of PMx shows two maxima along the year (one in late-winter/early-spring and another in summer), but this cycle is not followed by the AOD which shows only a summer maximum and a nearly bell shape. However, the annual means of both data sets show strong correlation (R=0.89) and similar decreasing trends of 40% (PM10) and 38% (AOD) for the 12-year record. PM10 and AOD daily data are moderately correlated (R=0.58), whereas correlation increases for monthly (R=0.74) and yearly (R=0.89) means. Scatter plots of AE vs. AOD and PR vs. PM10 have been used to characterize aerosols over the region. The PR vs. AE scatterplot of daily data shows no correlation due to the prevalence of intermediate-sized particles. As day-to-day correlation is low (especially for high turbidity events), a binned analysis was also carried out to establish consistent relationships between columnar and surface quantities, which is considered to be an appropriate approach for environmental and climate studies. In this way the link between surface concentrations and columnar remote sensing data is shown to provide useful information for aerosol characterization from a climatological context, despite some limitations.Thanks to MINECO for the financial support of the FPI grant BES-2012-051868; “Juan de la Cierva - Incorporación” grant IJCI-2014-19477 and project CMT2015-66742-R. We also thaks to the Environmental Council of the CyL Regional Government (“Consejería de Medio Ambiente, Junta de Castilla y León”) for supporting this research about atmospheric aerosols as well as Consejería de Educación for supporting the project VA100U14

Columnar and surface aerosol load over the Iberian Peninsula establishing annual cycles, trends, and relationships in five geographical sectors

Producción CientíficaThe study of atmospheric aerosol load over the Iberian Peninsula (IP) under a climatological perspective is accomplished by means of PM10 and AOD440nm measurements from EMEP and AERONET networks, respectively, in the period 2000-2013. The PM10 annual cycles in five Iberian sectors show a main maximum in summer and a secondary in spring, which is only observed in the southern area for the AOD climatology. The characteristics of PM10-AOD annual cycles of each geographical sector are explained by the different climatology of the air mass origins and their apportioning. The two magnitudes are correlated with a factor ranging between 20 and 90 depending on the sector. The temporal evolution of the aerosol load has shown a notable decrease in the IP since the 1980s. Statistically significant trends are obtained in the Northeastern sector with a reduction of 26% (period 1985-2000) for the total suspended particles, which continues for the PM10 data with a value of 35% per decade (2001-2013), and also in the whole column, 61% per decade in the AOD440nm (2004-2013).Financial supports from the Spanish MINECO (projects of ref. CGL2011-23413, CGL2012-33576) are also gratefully acknowledged

Integrated water vapor over the Arctic: Comparison between radiosondes and sun photometer observations

Producción CientíficaThe amplification of global warming because of the feedbacks associated with the increase in atmospheric moisture and the decrease in sea ice and snow cover in the Arctic is currently the focus of scientists, policy makers and society. The amplification of global warming is the response to increases in precipitation originally caused by climate change. Arctic predominant increases in specific humidity and precipitation have been documented by observations. In comparison, evapotranspiration in the Arctic is poorly known, in part, because the spatial and temporal sparsity of accurate in situ and remote sensing observations. Although more than 20 observations sites in the Arctic are available, where AERONET sun photometer integrated water vapor (IWV) measurements have been conducted, that information have been barely used. Here, we present a comparison of IWV observations from radiosondes and AERONET sun photometers at ten sites located across the Arctic with the goal to document the feasibility of that set of observations to contribute to the ongoing and future research on polar regions. Sun photometer IWV observations are averaged for three-time windows; 30 min, 6 and 24 h. The predominant dry bias of AERONET IWV observations with respect to radiosondes, identified at tropical and midlatitudes, is also present in the Arctic. The statistics of the comparison show robust results at eight of the ten sites, with precision and accuracy magnitudes below 8 and 2% respectively. The possible causes of the less robust results at the other two sites are discussed. In addition, the impact of selecting other temporal coincidence windows in the average sun photometer IWV used in the comparison were tested. Auto-correlation in diurnal sun photometer IWV could produce appreciable bias in the statistics used for the comparison. We suggest using only one pair of values per day, consisting in the daily mean IWV sun photometer and the IWV radiosonde observation value. This feature should be valid also for comparison of IWV from sun photometer and other instruments. Maximum 10% error level of IWV from sun photometer observations, when compared with radiosondes, have been found for the Arctic. It is in the same order of magnitude than at tropical and middle latitudes locations. It has been demonstrated the feasibility of AERONET IWV observations in the Arctic for research on this variable. AERONET standard instruments and its centralized-standard processing algorithm allow its IWV observations to be considered a relative standard dataset for the re-calibration of other instrumental IWV observations assuming radiosondes as the absolute standard dataset.Ministerio de Ciencia, Innovación y Universidades (grant RTI2018-097864-B-I00)Junta de Castilla y León (grant VA227P20)Junta de Extremadura - Fondo Europeo de Desarrollo Regional (grant GR21080 and project IB18092

Characterization of stratospheric smoke particles over the antarctica by remote sensing instruments

Australian smoke from the extraordinary biomass burning in December 2019 was observed over Marambio, Antarctica from the 7th to the 10th January, 2020. The smoke plume was transported thousands of kilometers over the Pacific Ocean, and reached the Antarctic Peninsula at a hight of 13 km, as determined by satellite lidar observations. The proposed origin and trajectory of the aerosol are supported by back-trajectory model analyses. Ground-based Sun–Sky–Moon photometer belonging to the Aerosol Robotic Network (AERONET) measured aerosol optical depth (500 nm wavelength) above 0.3, which is unprecedented for the site. Inversion of sky radiances provide the optical and microphysical properties of the smoke over Marambio. The AERONET data near the fire origin in Tumbarumba, Australia, was used to investigate the changes in the measured aerosol properties after transport and ageing. The analysis shows an increase in the fine mode particle radius and a reduction in absorption (increase in the single scattering albedo). The available long-term AOD data series at Marambio suggests that smoke particles could have remained over Antarctica for several weeks after the analyzed event.Fil: González, Ramiro. Universidad de Valladolid; EspañaFil: Toledano, Carlos. Universidad de Valladolid; EspañaFil: Román, Roberto. Universidad de Valladolid; EspañaFil: Mateos, David. Universidad de Valladolid; EspañaFil: Asmi, Eija Maria. Finnish Meteorological Institute; Finlandia. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; ArgentinaFil: Rodríguez, Edith. Finnish Meteorological Institute; FinlandiaFil: Lau, Ian C.. Commonwealth Scientific And Industrial Research Organisation Astronomy And Space Science; AustraliaFil: Ferrara, Jonathan. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; ArgentinaFil: D'elia, Raul Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; ArgentinaFil: Antuña Sánchez, Juan Carlos. Universidad de Valladolid; EspañaFil: Cachorro Revilla, Victoria Eugenia. Universidad de Valladolid; EspañaFil: Calle, Abel. Universidad de Valladolid; EspañaFil: de Frutos Baraja, Ángel Máximo. Universidad de Valladolid; Españ

Column integrated water vapor and aerosol load characterization with the new ZEN-R52 radiometer

Producción CientíficaThe study shows the first results of the column-integrated water vapor retrieved by the new ZEN-R52 radiometer. This new radiometer has been specifically designed to monitor aerosols and atmospheric water vapor with a high degree of autonomy and robustness in order to allow the expansion of the observations of these parameters to remote desert areas from ground-based platforms. The ZEN-R52 device shows substantial improvements compared to the previous ZEN-R41 prototype: a smaller field of view, an increased signal-to-noise ratio, better stray light rejection, and an additional channel (940 nm) for precipitable water vapor (PWV) retrieval. PWV is inferred from the ZEN-R52 Zenith Sky Radiance (ZSR) measurements using a lookup table (LUT) methodology. The improvement of the new ZEN-R52 in terms of ZSR was verified by means of a comparison with the ZEN-R41, and with the Aerosol Robotic Network (AERONET) Cimel CE318 (CE318-AERONET) at Izaña Observatory, a Global Atmosphere Watch (GAW) high mountain station (Tenerife, Canary Islands, Spain), over a 10-month period (August 2017 to June 2018). ZEN-R52 aerosol optical depth (AOD) was extracted by means of the ZEN–AOD–LUT method with an uncertainty of ±0.01 ± 0.13*AOD. ZEN-R52 PWV extracted using a new LUT technique was compared with quasi-simultaneous (±30 s) Fourier Transform Infrared (FTIR) spectrometer measurements as reference. A good agreement was found between the two instruments (PWV means a relative difference of 9.1% and an uncertainty of ±0.089 cm or ±0.036 + 0.061*PWV for PWV <1 cm). This comparison analysis was extended using two PWV datasets from the same CE318 reference instrument at Izaña Observatory: one obtained from AERONET (CE318-AERONET), and another one using a specific calibration of the 940-nm channel performed in this work at Izaña Atmospheric Research Center Observatory (CE318-IARC), which improves the PWV product.European Community Research Infrastructure Action (grant 262254)Ministerio de Ciencia, Innovación y Universidades (project RTI2018-097864-B-I00

La radiación solar en el sistema tierra-atmósfera

El Libro “Radiación Solar en el sistema Tierra-Atmósfera” es traducción de la versión original francesa titulada “Le Rayonnement Solaire dans l’ Environment Terrestre”, realizada por el Dr. Alain Chiron de la Casinière. Queremos resaltar aquí dos puntos importantes: uno de ellos es el relativo al carácter educativo y científico del mismo como elemento básico para el estudio de la radiación solar y el otro a la oportunidad de editar un libro de estas características en lengua española. El Sol es la única fuente de energía del planeta Tierra y por tanto el que determina su clima en toda su extensión. La energía radiada por el Sol que llega a nuestro planeta es una cantidad gigantesca de energía que ha de aprovecharse como prototipo de las “limpias”, en el momento en el que la sociedad se enfrenta al reto de la descarbonización como política base para enfrentar el Cambio Climático, considerado ya uno de los problemas fundamentales de la Sociedad. El libro se presenta con una estructura muy académica, obviamente al estilo francés, donde la repetición y rigor es un elemento fundamental en la enseñanza. El libro se estructura en cuatro amplios capítulos. El primero es una introducción a las nociones básicas de radiometría. El segundo capitulo está conformado en dos partes, una dedicada los conceptos propios de la astronomía terrestre y solar. La otra parte se dedica a estudiar ampliamente los procesos básicos de interacción radiación-atmósfera: absorción y dispersión o scattering, que conforman el proceso de atenuación o extinción de la radiación a través de la atmósfera mediante la ley de Beer-Lambert-Bouguer. El tercer capítulo se dedica a estudiar los modelos de radiación solar, desde los que evalúan la insolación a las irradiancias o flujos solares que incluyen tanto los modelos “Broadband” como espectrales, hasta llegar a los llamados Códigos de Cálculo de Transferencia Radiativa. El último capítulo se dedica a estructurar y clasificar los diferentes instrumentos de medida de la radiación y a los principios de calibración y medida, con un breve apunte sobre la acción biológica y química de la radiación solar. Todos estos capítulos se acompañan con una serie de observaciones a los conceptos fundamentales definidos, así como con una serie de problemas y ejercicios y su solución. El segundo punto a resaltar es la importancia de disponer en español de un libro de estas características pues apenas existen obras de este tipo, al ser comunes de uso las escritas en el idioma Inglés. El nivel académico/científico del libro es notable y en él aparecen toda una gama de términos que proceden en su mayoría de la terminología científica original del inglés, aunque en este caso particular además vienen de un libro en francés, es por ello que la obra original contiene una nomenclatura y un amplio índice de términos con un léxico en francés-inglés. Este libro debería de servir a la amplia comunidad de habla hispana como una herramienta elemental para la introducción al estudio de la radiación solar en el sistema global Tierra-Atmósfera.Fotografías de la cubierta pertenecientes al Grupo de Óptica Atmosférica de la Universidad de Valladolid (GOA

Comparison of CIMEL sun-photometer and ground-based GNSS integrated water vapor over south-western European sites

Financiación de acceso abierto gracias al acuerdo CRUE-CSIC con Elsevier.his work analyzes the integrated water vapor (IWV) measured at six Aerosol Robotic Network (AERONET) stations with nearby global navigation satellite system (GNSS) in the Iberian Peninsula for the period 2007–2018. It is shown that both instruments have a high correlation (R2 > 0.91), with small mbe below 1.5 mm and standard deviation (SD) below 2 mm. However, some dependences have been observed when MBE and SD are represented in bins of three variables: IWV, solar zenith angle (SZA), and aerosol optical depth (AOD). The greater or lesser amount of water vapor in the atmosphere seemed to be the more influential variable, increasing dry bias and SD with increasing IWV. Moreover, high SZA values were related to SD increases. A clear seasonal cycle for Cimel–GNSS differences was observed which was mainly related to IWV seasonal cycle. Additionally, AOD did not show a remarkable influence on Cimel–GNSS differences. Finally, the monthly differences are also analyzed with metadata information about Cimel device ID numbers, showing that, for long-term studies, this information can be very valuable.Este trabajo analiza el vapor de agua integrado (IWV) medido en seis estaciones de Aerosol Robotic Network (AERONET) con sistema global de navegación por satélite (GNSS) cercano en la Península Ibérica durante el período 2007-2018. Se muestra que ambos instrumentos tienen una alta correlación (R2 > 0,91), con mbe pequeño por debajo de 1,5 mm y desviación estándar (DE) por debajo de 2 mm. Sin embargo, se han observado algunas dependencias cuando MBE y SD se representan en contenedores de tres variables: IWV, ángulo cenital solar (SZA) y profundidad óptica del aerosol (AOD). La mayor o menor cantidad de vapor de agua en la atmósfera parece ser la variable más influyente, aumentando el sesgo seco y SD con el aumento de IWV. Además, los valores altos de SZA se relacionaron con aumentos de SD. Se observó un ciclo estacional claro para las diferencias Cimel-GNSS que se relacionó principalmente con el ciclo estacional IWV. Además, AOD no mostró una influencia notable en las diferencias Cimel-GNSS. Finalmente, las diferencias mensuales también se analizan con información de metadatos sobre los números de identificación de los dispositivos Cimel, lo que demuestra que, para estudios a largo plazo, esta información puede ser muy valiosa.This work was supported by Junta de Extremadura (Consejería de Economía, Ciencia y Agenda Digital) and European Regional Development Fund (ERDF A Way of Making Europe), through projects GR21080 and IB18092. We thank the principal investigators and their staff for their effort in establishing and maintaining the six AERONET sites used in this investigation. We also thank EUREF for the freely available tropospheric delay data and AEMet for the temperature and pressure data needed for this work. The authors are grateful to the Spanish Ministry of Science, Innovation and Universities for the support through the ePOLAAR project (RTI2018-097864-B-I00). Thanks are due to AERONET-PHOTONS-RIMA staff for providing observations and for the maintenance of the networks.peerReviewe