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CE376 LiDAR at Izaña (AEMET)

The CE376 LiDAR at Izaña (AEMET)

High above the clouds in the Canary Islands, scientists at the Izaña Observatory (AEMET) are using the CE376 LiDAR to explore the vertical structure of the atmosphere with unprecedented detail. This advanced instrument allows the aerosol science team to monitor aerosols moving across the Atlantic Ocean, providing critical insights into climate, air quality, and weather processes.

The CE376 is a compact dual-wavelength depolarization elastic lidar (532 and 808 nm). Its continuous monitoring capability makes it particularly valuable for atmospheric research. By analyzing data from both channels, the instrument provides detailed information on aerosol properties, allowing our team to capture the vertical distribution and dynamics of aerosols with unmatched precision.

Every day, the CE376 monitors Saharan dust events as they sweep across the Atlantic, revealing how mineral particles interact with clouds and affect radiation. Over time, it has also recorded comprehensive data on various aerosol types, including volcanic sulfate aerosols from the Cumbre Vieja eruption in September 2021, the devastating wildfire event on the island in August 2023, as well as long-range transported, aged wildfire plumes originating from Canadian wildfires during the late spring seasons. These observations have highlighted clear differences in particle size, shape, and optical properties, demonstrating the CE376’s suitability for continuous monitoring and characterization of both the temporal and vertical evolution of atmospheric aerosols.

Fig 1. MODIS VIS channel satellite image showing the Saharan dust over the Canary Islands on 20 August 2020.

Looking ahead, our team is continuously advancing the integration of CE376 lidar data together with sun photometer and in-situ measurements, while appliying sophisticated retrieval techniques such as GRASP (Generalized Retrieval of Aerosol and Surface Properties). This ongoing collaborative synergy is contributing to a more comprehensive understanding of aerosol optical properties and their effects on radiative forcing and regional climate.

More than just an instrument, the CE376 serves as a window into the atmosphere, revealing processes invisible to the naked eye but essential for science, society, and our understanding of a changing climate.

Fig 2. Saharan Air layer reaching the Izaña Observatory (AEMET). Courtesy of Conchy Bayo (AEMET)
Fig3. CE376 Lidar at Izaña Observatory (AEMET)
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NOAA-NASA MD campaign

NASA and NOAA pioneered a shipborne photometer campaign across the Atlantic

In 2023, NASA and NOAA launched a groundbreaking Atlantic campaign, placing an automated, AERONET-compatible sun photometer aboard a research vessel for the first time. The goal was simple but ambitious: collect high-quality aerosol optical depth (AOD) data over ocean regions, long neglected by traditional land-based monitoring networks. By measuring directly from the sea, scientists could fill a critical observational gap and strengthen satellite validation where fixed stations are sparse.

The instrument, a CIMEL CE318‑T, was specially adapted for shipborne deployment. Engineers stabilized it against vessel motion, added protective enclosures to withstand sea spray, and updated the firmware to maintain accurate sun-tracking and sky radiance measurements. Calibrations were aligned with AERONET protocols, ensuring the data matched the rigorous standards of land-based sites.

Adapted CIMEL CE 318‑T photometer installed on the vessel, stabilized against motion and protected from spray

Voyage across the Atlantic

Aboard the RV Marion Dufresne, the photometer captured aerosol characteristics along a route stretching from the tropical Atlantic, across the Intertropical Convergence Zone (ITCZ), and into the mid-latitudes. The ship crossed the ITCZ three times, recording interactions between Saharan dust, marine aerosols, and cloud systems. Over the three-year period, the dataset revealed patterns of episodic dust transport, background sea-spray, and long-range aerosol variability.

The campaign was conducted in close collaboration with the LOA through the AGORA-Lab, which ensured data quality control, calibration traceability, and scientific analysis in coordination with NASA’s AERONET team.

RV Marion Dufresne cruise track across the Atlantic, showing key aerosol sampling regions.

Key insights include:

  • Shipborne AOD retrievals were on par with established AERONET sites, confirming data quality.
  • The measurements provide essential reference points for satellite sensors like PACE and support improved aerosol transport modeling.

Bridging the gap in ocean observations

Oceanic aerosol measurements are scarce but essential for accurate climate modeling and satellite validation. By deploying high-precision, automated photometers on ships, NASA and NOAA created a bridge between sparse ground stations and satellite footprints. This approach allows for continuous monitoring, capturing both episodic events like dust storms and consistent background conditions.

The campaign also sets a template for future maritime aerosol monitoring. Plans include deploying similar instruments on additional vessels, extending geographic coverage, and integrating vertical profiling systems or unmanned aerial platforms. Data are archived in standardized formats and made publicly available, ensuring the scientific community can leverage the measurements for satellite match-ups, climate model validation, and process studies.

By venturing directly into the Atlantic, NASA and NOAA have opened a new chapter in aerosol observation. This initiative not only fills a critical gap in global monitoring but also enhances our understanding of aerosol-cloud-climate interactions in remote ocean regions.

References

  1. Torres, B. et al. 2025. Adaptation of the CIMEL‑318T to shipborne use: 3 years of automated AERONET-compatible aerosol measurements on board the research vessel Marion Dufresne. Atmos. Meas. Tech., 18, 4809‑4838. DOI:10.5194/amt‑18‑4809‑2025.
  2. Torres, B. 2024. Three years of aerosol measurements using an automated photometer on the first long-term AERONET ship site. LOA/Apolo Univ. Lille.
  3. AERONET / Maritime Aerosol Network (MAN) website.
  4. PACE Technical Report Series Vol 11. 2023. PACE Science Data Product Validation Plan. NASA.

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TRANSAMA campaign

TRANSAMA Campaign: Exploring aerosols across the oceans

In April–May 2023, the French research vessel Marion Dufresne II set sail from La Réunion Island toward Barbados on a unique mission: the TRANSAMA campaign (Transit to AMARYLLIS-AMAGAS). As part of the MAP-IO program (Marion Dufresne Atmospheric Program–Indian Ocean), this expedition aimed to deepen our understanding of aerosols — tiny particles suspended in the atmosphere – and their behavior over the open ocean.

Aerosols, whether transported from distant continents or generated locally, play a critical role in cloud formation, sunlight reflection, and climate dynamics. Yet, their behavior over the oceans remains poorly documented due to the logistical challenges of conducting continuous measurements at sea. TRANSAMA was designed to fill this gap by deploying state-of-the-art instrumentation capable of capturing both column-integrated and vertically resolved aerosol data in a fully autonomous, shipborne environment.

To meet this challenge, CIMEL collaborated closely with the Laboratoire d’Optique Atmosphérique (LOA) through their joint research structure, AGORA-Lab, which coordinated and supported all the instrumental installations aboard the ship.

Two CIMEL instruments formed the backbone of this observational campaign. The CE318-T Sun/Sky-Lunar photometer, set up permanently on board the ship since 2021, continuously recorded aerosol optical depth and particle size distribution during daylight hours, while the micro-LiDAR scanned the vertical structure of the atmosphere, revealing the layering of aerosols and their interactions with clouds.

Installed on the deck and carefully adapted for marine conditions, these instruments worked in harmony, providing a detailed picture of the atmosphere above the Atlantic.

Spatio-temporal variability of aerosol properties during the TRANSAMA campaign (21 April–15 May 2023) aboard the RV Marion Dufresne II. Measurements were conducted along the route from La Réunion Island to Barbados. (a) 3D variation of NRB at 532 nm from lidar measurements overlaid on a true-color image of the covered regions. (b) AOD at 440 nm and (c) EAE at 440/870 nm derived from photometer observations, displayed on topographic maps. Photometer data include L1 and L1.5 solar and lunar observations. Red345 pins mark the ports at Le Port (La Réunion), Recife (Brazil), and Bridgetown (Barbados).

Each observation contributed to a growing dataset that bridges the gap between local measurements and global atmospheric models.

Following the success of the 2023 campaign, the set up of a new CE376 lidar aboard Marion Dufresne in the framework of the OBS4CLIM project is scheduled for late October 2025. Once the lidar will be set up on board the vessel, it will record regular mobile measurements during the ship’s rotations from La Réunion island to the French Southern and Antarctic Lands (TAAF). These next voyages will further extend the temporal coverage of aerosol observations and help scientists understand the seasonal variations and long-range transport processes over the Indian and Atlantic Oceans.

CE318-T photometer
CIMEL micro-LiDAR

Key publications

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NASA-ARSET

NASA-ARSET reveals how AERONET contributes to air quality and climate applications

Ground-based networks such as AERONET play a crucial role in atmospheric science and air quality monitoring. During its latest NASA ARSET training titled “Atmospheric Composition Ground Networks Supporting Air Quality,” AERONET was showcased as a global benchmark in providing high-quality aerosol optical data for researchers, air quality managers, and decision-makers.

CIMEL CE318-T photometer enables fully autonomous, standardized, and long-term aerosol monitoring across diverse environments—from megacities to deserts and polar regions. With over 600 stations in 80+ countries, AERONET has become a global reference in satellite validation and atmospheric composition studies.

The ARSET training session reveals:

  • How ground-based observations complement satellite missions
  • The role of AERONET in policy-relevant applications
  • The importance of consistent, open-access data

You can access the training here: NASA ARSET Program

Key benefits of joining NASA-AERONET:

  1. Global data integration: As part of AERONET, CE318-T data integrates into a global network, allowing users to compare and access high-quality, standardized aerosol data worldwide, enhancing research with broader data context.
  2. Real-time data accessibility: AERONET provides near real-time data processing and availability on its online platform, allowing end-users to access and analyze current aerosol measurements efficiently.
  3. High-quality data: CE318-T photometers within AERONET are regularly calibrated at NASA’s calibration facilities, ensuring consistent, reliable, and high-quality data that meet strict scientific standards.
  4. Comprehensive aerosol data products: AERONET processes raw CE318-T measurements to deliver aerosol properties like aerosol optical depth (AOD), particle size distribution, and water vapor content, providing users with valuable insights without needing to process the raw data manually.
  5. Research collaboration opportunities: By participating in AERONET, end-users gain access to a collaborative network of scientists and research institutions globally, fostering opportunities for joint research projects and data sharing.
  6. Data validation for satellite missions: AERONET data is widely used to validate satellite aerosol measurements, allowing end-users to contribute to and benefit from satellite-derived aerosol research and applications in atmospheric studies.
  7. Recognition and credibility: Being part of AERONET enhances the credibility of the data collected, as the network is globally recognized in atmospheric sciences, potentially increasing the impact and visibility of users’ research.
Network of Networks – Calibration Centers/Sites
AERONET network – Calibration Centers/Sites
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CIMEL CE376 Lidar at the Cyprus Institute

CIMEL CE376 Lidar Strengthens Aerosol and Dust Monitoring at the Cyprus Institute

Nicosia, Cyprus – June 2025

TThe Cyprus Institute’s Climate and Atmosphere Research Center (CARE-C) continues to enhance its atmospheric observation capabilities with the CIMEL CE376, a compact, automatic aerosol lidar system providing high-resolution vertical profiles of aerosols and dust over the Eastern Mediterranean.

Installed on the institute’s rooftop platform, the CE376 has been operating continuously since late 2021, supporting advanced research and real-time environmental monitoring as part of the EMME-CARE project.

Advanced Technical Features:

  • Dual-wavelength operation at 532 nm and 808 nm.
  • Polarization channel at 532 nm for depolarization ratio retrievals.
  • Vertical range: Up to 10 km in daytime and 18 km at night.
  • Vertical resolution: 15 m; Temporal resolution: 1 s.

This system is designed to be compact and energy-efficient, suitable for continuous, remote, and even mobile operations — ideal for climate-sensitive regions like the Eastern Mediterranean and the Middle East.

Accurate Dust and Aerosol Profiling

The CE376 provides real-time vertical profiles of:

  • Particle backscatter and extinction coefficients
  • Volume depolarization ratios for aerosol typing
  • Planetary boundary layer (PBL) height estimation

Recent observations show the lidar’s capacity to clearly distinguish between clean atmospheric layers and dust intrusions originating from North Africa. Notably, during spring 2024, several Saharan dust events were recorded over Cyprus, with elevated layers reaching above 5 km and enhanced depolarization ratios indicating non-spherical particles consistent with mineral dust.

Calibration and Data Quality

An internal calibration and data correction procedure has been implemented to ensure the high accuracy of depolarization ratio measurements. Molecular depolarization values are now well-aligned with theoretical expectations (~0.0033), allowing for robust identification and classification of aerosol types.

The processed and corrected data are openly available via the Cyprus Institute’s EMME-CARE Upper-Air Data Portal, providing the scientific community and policymakers with vital insights into aerosol dynamics, air quality, and climate interactions across the region.

The site also hosts a CIMEL CE318-T photometer as part of the AERONET network, enabling valuable synergy with the CE376 for improved aerosol classification and dust monitoring.

Explore real-time data here: https://emme-care.cyi.ac.cy/data/upper-air-over-cyprus/

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Aerosol optical depth comparison between GAW-PFR and AERONET-Cimel radiometers from long-term (2005–2015) 1 min synchronous measurements

CE318-T Izaña

Aerosol optical depth comparison between GAW-PFR and AERONET-Cimel radiometers from long-term (2005–2015) 1 min synchronous measurements

August 9, 2019

A comprehensive comparison of more than 70 000 synchronous 1 min aerosol optical depth (AOD) data from three Global Atmosphere Watch precision-filter radiometers (GAW-PFR), traceable to the World AOD reference, and 15 Aerosol Robotic Network Cimel radiometers (AERONET-Cimel), calibrated individually with the Langley plot technique, was performed for four common or “near” wavelengths, 380, 440, 500 and 870 nm, in the period 2005–2015.

The goal of this study is to assess whether, despite the marked technical differences between both networks (AERONET, GAW-PFR) and the number of instruments used, their long-term AOD data are comparable and consistent.

The percentage of data meeting the World Meteorological Organization (WMO) traceability requirements (95 % of the AOD differences of an instrument compared to the WMO standards lie within specific limits) is >92 % at 380 nm, >95 % at 440 nm and 500 nm, and 98 % at 870 nm, with the results being quite similar for both AERONET version 2 (V2) and version 3 (V3). For the data outside these limits, the contribution of calibration and differences in the calculation of the optical depth contribution due to Rayleigh scattering and O3 and NO2 absorption have a negligible impact. For AOD >0.1, a small but non-negligible percentage (∼1.9 %) of the AOD data outside the WMO limits at 380 nm can be partly assigned to the impact of dust aerosol forward scattering on the AOD calculation due to the different field of view of the instruments. Due to this effect the GAW-PFR provides AOD values, which are ∼3 % lower at 380 nm and ∼2 % lower at 500 nm compared with AERONET-Cimel. The comparison of the Ångström exponent (AE) shows that under non-pristine conditions (AOD >0.03 and AE <1) the AE differences remain <0.1. This long-term comparison shows an excellent traceability of AERONET-Cimel AOD with the World AOD reference at 440, 500 and 870 nm channels and a fairly good agreement at 380 nm, although AOD should be improved in the UV range.

Citation: Cuevas, E., Romero-Campos, P. M., Kouremeti, N., Kazadzis, S., Räisänen, P., García, R. D., Barreto, A., Guirado-Fuentes, C., Ramos, R., Toledano, C., Almansa, F., and Gröbner, J.: Aerosol optical depth comparison between GAW-PFR and AERONET-Cimel radiometers from long-term (2005–2015) 1 min synchronous measurements, Atmos. Meas. Tech., 12, 4309–4337, https://doi.org/10.5194/amt-12-4309-2019, 2019.

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Sunbelt Spectra comparison with Standard ASTM G173: the Chilean case

Sunbelt Spectra comparison with Standard ASTM G173: the Chilean case

December, 2017

Two spectra of solar direct normal irradiance (including circumsolar) are estimated based on spatio-temporal averages of the relevant atmospheric parameters extracted from two different databases: MODIS satellite sensor retrievals and AERONET sun photometer network. The satellite database is used to calculate an average spectrum for the area of the Atacama Desert. The AERONET database is used for two purposes: (i) to apply bias-removal linear methods to correct the MODIS parameters over Atacama, and (ii) to calculate an average local spectrum for the Paranal station. The SMARTS radiative transfer model is used to obtain the three spectra developed in this study. Both the Atacama and Paranal spectra are compared against each other and also to the world reference, ASTM G173. In one of the cases, significant differences are found for short wavelengths. In order to quantify the relative importance of these spectral differences, the propagation of errors due to the use of each spectrum is evaluated for CSP applications over the Atacama Desert, considering twelve different scenarios involving the reflectance, transmittance or absorptance of various materials.

Citation: Marzo, Aitor & Polo, Jesus & Wilbert, Stefan & Gueymard, Chris & Jessen, Wilko & Ferrada, Pablo & Alonso-Montesinos, Joaquín & Ballestrín, Jesús. (2017). Sunbelt Spectra comparison with Standard ASTM G173: the Chilean case. AIP Conference Proceedings. 2033. 10.1063/1.5067195.

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Image source: Pixabay

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NASA AERONET

NASA AERONET

Aerosols, these tiny particles of the lower atmosphere, are one important component of atmosphere affecting climate (radiative effects, water cycle) and air quality.

For characterizing and monitoring aerosols, water wapor and clouds, LOA and Cimel, in collaboration with NASA’s GSFC, developed the robotic solar photometer for the AERONET network in the early 1990s. The meeting between CNRS and NASA researchers and the industrial company Cimel led to the definition of an automatic, robust, autonomous solar photometer that transmits its data by radio, providing AOD and particle size in real time. In 1998, the French component (PHOTONS) was awarded the INSU Observation Service label.

Cimel is NASA – AERONET’s exclusive supplier of automatic Sun Sky Lunar photometers (CIMEL CE318-T) operating in near real time and providing aerosol optical and columnar microphysical properties.

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A 10-year characterization of the Saharan Air Layer lidar ratio in the subtropical North Atlantic

A 10-year characterization of the Saharan Air Layer lidar ratio in the subtropical North Atlantic

May 10, 2019

Particle extinction-to-backscatter ratio (lidar ratio) is a key parameter for a correct interpretation of elastic lidar measurements. Of particular importance is the determination of the lidar ratio of the Saharan Air Layer mineral dust transported into the free troposphere over the North Atlantic region. The location of the two sun photometer stations managed by the Izaña Atmospheric Research Centre (IARC) on the island of Tenerife and a decade of available micropulse lidar (MPL) data allow us to determine the lidar ratio under almost pure-dust conditions. This result can be considered representative of the Saharan dust transported westward over the North Atlantic in the subtropical belt.

Three different methods have been used to calculate the lidar ratio in this work: (1) using the inversion of sky radiance measurements from a sun–sky photometer installed at the Izaña Observatory (2373 m a.s.l.) under free-troposphere conditions; (2) the one-layer method, a joint determination using a micropulse lidar sited at the Santa Cruz de Tenerife sea-level station and photometric information considering one layer of aerosol characterized by a single lidar ratio; and (3) the two-layer method, a joint determination using the micropulse lidar and photometric information considering two layers of aerosol with two different lidar ratios. The one-layer method only uses data from a co-located photometer at Santa Cruz de Tenerife, while the two-layer conceptual approach incorporates photometric information at two heights from the observatories of Izaña and Santa Cruz de Tenerife. The almost pure-dust lidar ratio retrieval from the sun–sky photometer and from the two-layer method give similar results, with lidar ratios at 523 nm of 49 ± 6 and 50 ± 11 sr. These values obtained from a decade of data records are coincident with other studies in the literature reporting campaigns in the subtropical North Atlantic region. This result shows that the two-layer method is an improved conceptual approach compared to the single-layer approach, which matches the real lower-troposphere structure well. The two-layer method is able to retrieve reliable lidar ratios and therefore aerosol extinction profiles despite the inherent limitations of the elastic lidar technique.

We found a lack of correlation between lidar ratio and Ångström exponent (α), which indicates that the dust lidar ratio can be considered independent of dust size distribution in this region. This finding suggests that dust is, under most atmospheric conditions, the predominant aerosol in the North Atlantic free troposphere, which is in agreement with previous studies conducted at the Izaña Observatory.

Citation: Berjón, A., Barreto, A., Hernández, Y., Yela, M., Toledano, C., and Cuevas, E.: A 10-year characterization of the Saharan Air Layer lidar ratio in the subtropical North Atlantic, Atmos. Chem. Phys., 19, 6331-6349, https://doi.org/10.5194/acp-19-6331-2019, 2019.

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Photo credits: NASA-GSFC

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The plume of the Icelandic volcano Bardarbunga pollutes the air in the Nord – Pas de Calais

The plume of the Icelandic volcano Bardarbunga pollutes the air in the Nord – Pas de Calais

At the end of September 2014, the Nord – Pas de Calais region suffered an episode of heavy air pollution due to the eruption of the Icelandic volcano Bardarbunga, which has already been going on for more than a month.

The analysis of observations of the volcanic plume, obtained from the ground, thanks to CIMEL photometers and LiDAR, and by satellite, by a team of researchers, engineers and technicians from the Laboratoire d’optique atmosphérique (LOA, CNRS / Université Lille 1) in collaboration with the association for monitoring air quality atmo Nord – Pas de Calais, allowed them to describe the journey, from Iceland, of the volcanic plume and its arrival in the lowest layers of the French atmosphere.