Remote sensing of aerosols at night with the CoSQM sky brightness data

Aerosol optical depth is an important indicator of aerosol particle properties and their associated radiative impacts. AOD determination is very important to achieve relevant climate modelling. Most remote sensing techniques to retrieve aerosol optical depth are applicable to daytime given the high level of light available. The night represents half of the time but in such conditions only a few remote sensing methods are available. Among these approaches, the most reliable are moon photometers and star photometers. In this paper, we attempt to fill gaps in the aerosol detection performed with the aforementioned techniques using night sky brightness measurements during moonless nights with the novel CoSQM, a portable, low-cost and open-source multispectral photometer. In this paper, we present an innovative method for estimating the aerosol optical depth using an empirical relationship between the zenith night sky brightness measured at night with the CoSQM and the aerosol optical depth retrieved during daytime from the AErosol Robotic NETwork

Spectral aerosol radiative forcing and efficiency of the La Palma volcanic plume over the Izaña Observatory

On 19 September 2021, a volcanic eruption began on the island of La Palma (Canary Islands, Spain). The eruption has allowed the assessment of an unprecedented multidisciplinary study on the effects of the volcanic plume. This work presents the estimation of the spectral direct radiative forcing (∆F) and efficiency (∆F E f f) from solar radiation measurements at the Izaña Observatory (IZO) located on the island of Tenerife (∼140 km from the volcano). During the eruption, the IZO was affected by different types of aerosols: volcanic, Saharan mineral dust, and a mixture of volcanic and dust aerosols. Three case studies were identified using ground based (lidar) data, satellite-based (Sentinel5P Tropospheric Monitoring Instrument, TROPOMI) data, reanalysis data (Modern-Era Retrospective Analysis for Research and Applications, version 2, MERRA-2), and backward trajectories (Flexible Trajectories, FLEXTRA), and subsequently characterised in terms of optical and micro-physical properties using ground based sun-photometry measurements. Despite the ∆F of the volcanic aerosols being greater than that of the dust events (associated with the larger aerosol load present), the ∆F E f f was found to be lower. The spectral ∆F E f f values at 440 nm ranged between −1.9 and −2.6 Wm−2nm−1AOD−1 for the mineral dust and mixed volcanic and dust particles, and between −1.6 and −3.3 Wm−2nm−1AOD−1 for the volcanic aerosols, considering solar zenith angles between 30◦ and 70◦, respectively.The authors also acknowledge the support of ACTRIS, Ministerio de Ciencia e Innovación of Spain, through the projects SYNERA: PID2020-118793GA-I00 and RT2018- 097864-B-I00, and Junta de Castilla y León grant N◦. VA227P20

Medida del vapor de agua integrado en columna sobre el Observatorio Atmosférico de Izaña mediante radiometría de microondas. Comparación con otras técnicas

Se presentan en este estudio los resultados de la comparación entre las medidas del vapor de agua integrado en la columna total atmosférica (IWV), obtenido con un radiómetro de microondas RPG-LHATPRO de la serie G5 (MWR), en el Observatorio Atmosférico de Izaña (IZO) y los obtenidos mediante las técnicas FTIR, EKO MS-711, CIMEL, GNSS y radiosondas Väisala RS41 durante diferentes períodos de tiempo comprendidos entre mayo de 2020 y abril de 2023. Los resultados de la comparación indican una alta trazabilidad del MWR superior al 90% con la mayoría de las técnicas, siendo la técnica FTIR, con un 99%, la de mayor trazabilidad durante el día y las RS41, con un 98%, durante la noche. Como consecuencia, estas dos últimas técnicas podrían usarse en estudios que involucren medidas del IWV con el MWR en los que se necesiten complementar períodos de ausencias de datos para el día y la noche, respectivamente. El estudio nos ha permitido estimar también la exactitud y precisión de las medidas del IWV, así como el límite de detección de las diferentes técnicas, constatando que las técnicas MWR y CIMEL Lunar son las de mayor exactitud y precisión con límites de detección de 0.18 mm y 0.13 mm y máximas incertidumbres de 0.77 mm y 0.93 mm, respectivamente. Se constata también que el instrumento MWR mide más IWV que cualquiera de las otras técnicas, tanto de día como de noche (entre un 4% y un 22% más, dependiendo de la técnica). Asimismo, las diferencias entre el IWV del MWR y el del resto de técnicas muestran, en valor absoluto, un progresivo aumento lineal con el contenido de vapor de agua, tanto de día como de noche, una ligera disminución con el ángulo cenital solar y un muy débil aumento con el ángulo cenital lunar. El ángulo de fase lunar influye en la comparación disminuyendo las diferencias entre MWR y CIMEL Lunar en el rango [-30º, 30º]

Volcanic eruption of Cumbre Vieja, La Palma, Spain: A first insight to the particulate matter injected in the troposphere

The volcanic eruption of Cumbre Vieja (La Palma Island, Spain), started on 19 September 2021 and was declared terminated on 25 December 2021. A complete set of aerosol measurements were deployed around the volcano within the first month of the eruptive activity. This paper describes the results of the observations made at Tazacorte on the west bank of the island where a polarized micro-pulse lidar was deployed. The analyzed two-and-a-half months (16 October–31 December) reveal that the peak height of the lowermost and strongest volcanic plume did not exceed 3 km (the mean of the hourly values is 1.43 ± 0.45 km over the whole period) and was highly variable. The peak height of the lowermost volcanic plume steadily increased until week 11 after the eruption started (and 3 weeks before its end) and started decreasing afterward. The ash mass concentration was assessed with a method based on the polarization capability of the instrument. Two days with a high ash load were selected: The ash backscatter coefficient, aerosol optical depth, and the volume and particle depolarization ratios were, respectively, 3.6 (2.4) Mm−1sr−1, 0.52 (0.19), 0.13 (0.07) and 0.23 (0.13) on 18 October (15 November). Considering the limitation of current remote sensing techniques to detect large-to-giant particles, the ash mass concentration on the day with the highest ash load (18 October) was estimated to have peaked in the range of 800–3200 μg m−3 in the lowermost layer below 2.5 km.This research was funded by the Spanish Ministry of Science and Innovation (PID2020- 118793GA-I00, PID2019-104205GB-C21, EQC2018-004686-P and PID2019-103886RB-I00), the H2020 program from the European Union (GA no. 19ENV04, 654109, 778349, 871115 and 101008004), and the Unit of Excellence “María de Maeztu” (MDM-2017-0737) financed by the Spanish State Research Agency (AEI). The authors wish to thank ACTRIS, AEROSPAIN and Junta de Castilla y León (ref: VA227P20) for supporting the calibration of the AERONET sun photometers used in this publication, and also to Ayuntamiento de Tazacorte, Ayuntamiento de Fuencaliente and Cabildo Insular de La Palma for their help in terms of infrastructure and logistics. M.-Á.L.-C. and C.V.C.-P. are supported by the INTA predoctoral contract program. E.J.W. is funded by the NASA Radiation Sciences Program and Earth Observing System.Peer ReviewedArticle signat per 16 autors/es: Michaël Sicard (1,2), Carmen Córdoba-Jabonero (3), Africa Barreto (4), Ellsworth J. Welton (5), Cristina Gil-Díaz (1),Clara V. Carvajal-Pérez (3), Adolfo Comerón (1), Omaira García (4), Rosa García (6), María-Ángeles López-Cayuela (3),Constantino Muñoz-Porcar (1), Natalia Prats (4), Ramón Ramos (4), Alejandro Rodríguez-Gómez (1), Carlos Toledano (7), Carlos Torres (4) // (1) CommSensLab, Department of Signal Theory and Communications, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain; (2) Ciències i Tecnologies de l’Espai-Centre de Recerca de l’Aeronàutica i de l’Espai/Institut d’Estudis Espacials de Catalunya (CTE-CRAE/IEEC), Universitat Politècnica de Catalunya, 08034 Barcelona, Spain; (3) Atmospheric Research and Instrumentation Branch, Instituto Nacional de Técnica Aeroespacial (INTA), 28850 Torrejon de Ardoz, Spain; (4) Izaña Atmospheric Research Center, State Meteorological Agency of Spain (AEMET), 38001 Santa Cruz de Tenerife, Spain: (5) Code 612, Goddard Space Flight Center, National Aeronautics and Space Administration, Greenbelt, MD 20771, USA; (6) TRAGSATEC, 28006 Madrid, Spain; (7) Group of Atmospheric Optics, Universidad de Valladolid, 47011 Valladolid, SpainPostprint (published version

Spectral aerosol optical depth from SI-traceable spectral solar irradiance measurements

Spectroradiometric measurements of direct solar irradiance traceable to the SI were performed by three spectroradiometer systems during a 3-week campaign in September 2022 at the Izaña Atmospheric Observatory (IZO) located on the island of Tenerife, Canary Islands, Spain. The spectroradiometers provided direct spectral irradiance measurements in the spectral ranges 300 to 550 nm (QASUME), 550 to 1700 nm (QASUME-IR), 300 to 2150 nm (BiTec Sensor, BTS), and 316 to 1030 nm (Precision Solar Spectroradiometer, PSR), with relative standard uncertainties of 0.7 %, 0.9 %, and 1 % for QASUME/QASUME-IR, the PSR, and the BTS respectively. The calibration of QASUME and QASUME-IR was validated prior to this campaign at Physikalisch-Technische Bundesanstalt (PTB) by measuring the spectral irradiance from two spectral irradiance sources, the high-temperature blackbody BB3200pg as a national primary standard and the tuneable laser facility TULIP

Aerosol characterisation in the subtropical eastern North Atlantic region using long-term AERONET measurements

A comprehensive characterisation of atmospheric aerosols in the subtropical eastern North Atlantic has been carried out using long-term ground-based Aerosol Robotic NETwork (AERONET) photometric observations over the period 2005–2020 from a unique network made up of four stations strategically located from sea level to 3555 m on the island of Tenerife. This site can be considered a sentinel for the passage of airmasses going to Europe from Africa, and therefore the aerosol characterisation performed here adds important information for analysing their evolution during their path toward Northern Europe. Two of these stations (Santa Cruz de Tenerife – SCO – at sea level and La Laguna – LLO – at 580 m a.s.l.) are located within the marine atmospheric boundary layer (MABL), and the other two (Izaña – IZO – at 2373 m a.s.l. and Teide Peak – TPO – at 3555 m a.s.l.) are high mountain stations within the free troposphere (FT). Monthly climatology of the aerosol optical depth (AOD), Ångström exponent (AE), aerosol concentration, size distribution and aerosol optical properties has been obtained for the MABL and FT. Measurements that are quite consistent across the four sites have been used to categorise the main atmospheric scenarios, and these measurements confirm an alternation between predominant background conditions and predominant dust-loaded Saharan air mass conditions caused by seasonal dust transport over the subtropical North Atlantic. Background conditions prevail in the MABL and FT for most of the year, while dust-laden conditions dominate in July and August.The authors also acknowledge the support from ACTRIS, Ministerio de Ciencia e Innovación, Spain, through the projects SYNERA (PID2020-118793GA-I00) and ePOLAAR (RTI2018-097864-BI00) and from Junta de Castilla y León (grant no. VA227P20)

Estimation of the Mass Concentration of Volcanic Ash Using Ceilometers: Study of Fresh and Transported Plumes from La Palma Volcano

This study presents a synergistic approach to the study of the aerosol optical and microphysical properties measured in La Palma, Spain, during the 2021 eruption of the Cumbre Vieja volcano (from 19 September to 13 December 2021). This study aims to characterize the different phases of the volcanic eruption using the spatio-temporal evolution of the event together with the mass concentration quantification of four different atmospheric layers. The impact of the plume’s pathway that reached the South of France is analyzed. Here, passive and active remote sensors were used, namely CL51 and CL61 ceilometers and AERONET sunphotometers. The attenuated backscattering ranged from 0.8 to 9.1 × 10−6 (msr)−1 and the volume depolarization ratio measured nearby the volcano was up to 0.3. The ash plume remained within the first 4 km agl, with intense episodes that reached mean aerosol optical depth values of up to 0.4. Thirteen study cases were selected where coarse mode was dominant over fine mode. For the data selection, the fine and coarse lidar ratios found were 3.9 ± 0.8 and 21.0 ± 3.8 sr in the north and 6.9 ± 1.8 and 30.1 ± 10.3 sr in the south. The ash mass concentration reached moderate levels with maximum values of up to 313.7 μgm−3.This work was financially supported by ONERA within the framework of the PROMETE project 2017–2021; the Spanish Ministry of Science and Innovation (PID2019-103886RB-I00\AEI\10.13039\501100011033); and the H2020 program from the European Union (GA no. 654109, 778349, 871115, 101008004 and 101086690)

Sharp increase of Saharan dust intrusions over the Western Mediterranean and Euro-Atlantic region in winters 2020–2022 and associated atmospheric circulation [Discussion paper]

During the winters of the 2020–2022 period, several intense North African dust intrusions affected Europe. Some of them displayed a duration never recorded before. They were referred to as exceptional by several international operational and research institutions considering that wintertime is the season with minimum dust activity in the Mediterranean and Europe. These anomalous winter events with origin in North Africa largely affected western Mediterranean. The main objective of the present work is to analyse the atmospheric drivers (synoptic and large-scale environments) of wintertime (from January to March) dust events over the region covering North Africa, the Western Mediterranean and the Euro-Atlantic during the period 2003–2022. Overall, our results indicate large interannual variability over the study period. A dust catalogue of dust events identified by aerosols retrievals from satellite and aerosol reanalysis products shows a very irregular record and large differences between winter months. The analyses demonstrate a positive anomaly in dust concentration and maximum altitude during the dust events of 2020–2022 in comparison with those of previous years (2003–2019). Winter dust events over western Mediterranean are associated with enhanced blocking activity over the Euro-Atlantic sector, which favours the obstruction of the westerlies and the occurrence of cut-off lows at subtropical latitudes. However, these high-pressure systems can exhibit a large variety of configurations, including meridional dipole blocking patterns with poleward shifted jets or Mediterranean subtropical ridges with an intensified mid-latitude jet. The former was more frequent during the reference 2003–2019 period, whereas the latter was relatively common during the anomalous 2020–2022 period

ICOS-Spain. Activity Report 2021-2022

Editors: O.E. García, S.F. León-Luis y Melchor González-Dávila.[ES]El Sistema Integrado de Observación del Carbono (ICOS) es una infraestructura europea de investigación (ERIC) que tiene por objetivo la monitorización de gases de efecto invernadero. Esta iniciativa está financiada por la Unión Europea y países socios. La Asamblea General de ICOS aprobó la solicitud de adhesión de España, y su incorporación se hizo oficial el 1 de enero de 2021. En la actualidad, la red ICOS-España, donde AEMET ejerce la coordinación, cuenta con cinco estaciones que cubren los dominios: atmosférico, oceánico y de ecosistema. El "Informe de Actividades ICOS-España: 2021-2022" presenta las principales tareas llevadas a cabo en cada estación, con el objetivo de obtener la certificación ICOS y mostrar el estado actual de avance en este proceso. Además, el informe también resume las actividades de comunicación y difusión realizadas por los investigadores que forman parte del nodo nacional.[EN]The Integrated Carbon Observation System (ICOS) is a European Research Infrastructure (ERIC) that aims to monitor greenhouse gases. This initiative is funded by the European Union and partner countries. The ICOS General Assembly approved Spain's membership, and its incorporation officially began on January 1, 2021. Currently, the ICOS-Spain national network, coordinated by AEMET, has five stations covering atmospheric, oceanic, and ecosystem domains. The "ICOS-Spain Activities Report: 2021-2022" presents the main tasks carried out at each station, with the aim of obtaining ICOS certification and the current situation of this process. In addition, the report also summarizes the communication and dissemination activities carried out by the researchers who are part of the national node

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