The implantation of CE318-T photometers on offshore and coastal platforms constitutes a major turning point for atmospheric and ocean color applications.

Keywords : Aerosols, photometer, water radiance, monitoring, ocean properties, ocean color, Earth observation, remote sensing, CAL/VAL, SeaPRISM.

17th December 2021

The main substances that affect the color of the ocean include dissolved organic matter, living phytoplankton with chlorophyll pigments, and non-living particles like marine snow and mineral sediments. Ocean color data have a critical role in operational observation systems monitoring coastal eutrophication, harmful algal blooms, and sediment plumes. Scientists rely on satellite observations to monitor Ocean Color (OC) parameters, such as chlorophyll a concentration (Chla) and inherent optical properties of water (IOP), to better understand the role of the ocean in the Earth’s climate.

However, the current satellite measurement systems can provide only coarse spatial resolution, with relevant lack of data.

Thus, AERONET Ocean Color saw the light of day in 2002. This new component of AERONET (NASA AErosol RObotic NETwork) aims at providing more data concerning satellites measurements as there is a lack of insights in the monitoring of marine aerosols and water radiance. Since 2002, more than 31 OC measurement sites have been integrated on the network through offshore fixed platforms and coastal platforms all around the world.

Its particularity is that the measurements are taken from the radiance emerging from the sea using CE318-TV12-OC (SeaPRISM) Cimel photometers. By measuring the water radiance from the sea with instruments installed on coastal/offshore platforms or boats, Cimel improves the accuracy of satellites measurements. AERONET decided in 2015, after full validation, to accept only the CE318-T for new photometers entering the network. Below is a representative drawing of the measurement principle of the CE318-TV12-OC (SeaPRISM) photometer:

Figure 1: Measurement principle of the Cimel CE318-TV12-OC (SeaPRISM).

Many missions are conducted by AERONET-OC to collect ocean color data and measurements. Below, one of these campaigns conducted on an offshore platform (AAOT) in the Adriatic Sea.

Figure 2: AERONET OC site located in the Acqua Alta Oceanographic Tower (AAOT) in the Gulf of Venice in the Northern Adriatic Sea in July 2018.

Figure 3: Measurements performed at AERONET-OC AAOT – Scatterplot of LIOP WN(λ) versus LChla WN(λ).

Click Here to read the article!

Citation: Zibordi, Giuseppe, Brent N. Holben, Marco Talone, Davide D’Alimonte, Ilya Slutsker, David M. Giles, and Mikhail G. Sorokin. «Advances in the Ocean Color Component of the Aerosol Robotic Network (AERONET-OC)”, Journal of Atmospheric and Oceanic Technology 38, 4 (2021): 725-746, accessed Sep 17, 2021,


Volcano eruption of Mount Aso in Japan – A peak of AOD due to volcanic ashes

Keywords : Photometer, Aerosols Optical Depth, Atmosphere, volcanic eruption, Ashes.

17th November 2021

The volcano of Mount Aso located in the south of the Japanese archipelago on the island of Kyushu erupted this Wednesday, October 20, releasing volcanic ashes up to 3,5 kilometers in the atmosphere during the strongest eruption time.

The volcano had not been active since 2016, local authorities are advising residents to remain vigilant of volcanic ashes and gases on the leeward side of the Nakadake crater. As a matter of fact, the gas and projectiles created a cloud that is denser than the surrounding air and which is an extremely hot ash plume due to the turbulence between the flow and the overlying air.

One of the Cimel CE318-T photometer is currently providing atmospheric aerosols measurements near the volcano eruption. Indeed, the NASA AERONET site based on the offshore platform of Ariake observation tower located in Ariake Sea in Japan, is about 5 kilometers from the coast of Saga city in Ariake Sea.

Figure 1: Google Earth satellite image showing the position of the NASA AERONET Ariake Tower site in relation to the Mount Aso volcano in Kyushu Island (Japan).

Figure 2: Data provided by the Cimel photometer in the Ariake Tower operated by Saga University, depicting Aerosols Optical Depth in the atmosphere.

We have collected data recorded by the Cimel CE318 photometer which measures the Aerosols Optical Depth (AOD) in the atmosphere. We note a peak of the AOD on October 21, a day after the volcanic eruption.

With the addition of Cimel CE376 LiDAR, it would be possible to obtain more high added value parameters such as the characterization, location and the extinction and backscatter profile of mass concentration of this kind of ash aerosols in the atmosphere.

See more on our AAMS solution which consists in the synergy between our LiDARs and our photometers.


La Palma eruption (Canary Islands) – volcanic plumes tracking by our LiDARs

Keywords : LiDARs, Aerosols, Atmosphere, La Palma, Cumbre Vieja volcano, CE376.

6th October 2021

The Cumbre Vieja volcano on La Palma in the Canary Islands erupted on 19th September for the first time since 1971 resulting in large lava flows and evacuations.

Due to the volcanic eruption, nearly 10 000 tons of sulfur dioxide are released in the atmosphere every day. The risks generated are acid rain and deterioration of air quality which can lead to respiratory problems.

In a few words, this phenomenon is due to the fact that the lava of the volcano which reaches 1000°C meets the sea water which is at around 20°C. Therefore, the sodium chloride contained in the sea breaks down the water into oxygen and hydrogen. However, when hydrogen meets chlorine, they turn into hydrochloric acid which is an extremely dangerous gas.

There are many consequences such as the impact on the air quality which directly concerns the surrounding populations who breathe a toxic smoke harmful for their health.

Air traffic is also strongly impacted as all the flights departing from the island have been cancelled. These disturbances are also due to the lack of instruments measuring aerosols (such as LiDARs) to accurately identify the location of the volcanic ash as well as its characteristics and concentration.

Our CE376 LiDARs in AEMET (Izaña) is tracking plumes of the volcanic ash from the volcanic eruption on La Palma and here are some results to illustrate it.

Figure 1: Quicklook revealing the volcano plumes as captured on 24 September by AEMET in Izaña.

The volcano is propelling air into the atmosphere which meets a thermal inversion – a reversal of the normal behavior of temperature in the troposphere where a layer of hot air sits above a layer of cooler air.

Figure 2: Picture by Virgilio Carreño (Izaña Atmospheric research center, AEMET) showing the interaction of the gas and ash plume of the eruptive column leaving the volcano with the altitude thermal inversion layer of the atmosphere through which the Sahara desert dust transcends.

ATTO project

ATTO: the Amazon Tall Tower Observatory, an Amazon research project

Keywords : ATTO, Aerosols, Photometer, Atmosphere

The Amazon Tall Tower Observatory (ATTO) is the world’s highest research facility located in the middle of the Amazon rainforest in northern Brazil. It is a research site with a 325 meters tower for atmospheric observations.

This joint German-Brazilian project was launched in 2008 in order to further the understanding of the Amazon rainforest and its interaction with the soil beneath and the atmosphere above. This is made possible by recording continuously meteorological, chemical and biological data such as greenhouse gases or aerosols.

Scientists and researchers on site hope to gain insights into how the Amazon interacts with the atmosphere and the soil. This region is very important for the global climate as Saharan dust, biomass smoke from Africa, urban and marine aerosols come from long distances due to the winds. It is vital to get a better understanding of this area for environmental decisions.

On this gigantic tower, a CE318-T photometer is installed at 210 meters from the ground and allows a more efficient calculation of the quantity of aerosols present in the air around this site. The photometer uses NASA’s AERONET calibration system to collect the most reliable data possible.

Cimel photometer on the tower (© NASA AERONET)

At the core of the project is to learn more about biogeochemical cycles, the water cycle and energy fluxes in the Amazon. The goal is to determine their impact on global climate and how they are influenced by the changing climate and land-use change.

ATTO teams strive to close a gap in the global climate monitoring network and want to improve climate prediction models and to recognize the importance of the Amazon within the climate system.

Thanks to our sun-photometer, the scientists on site were able to collect information on daily mean AOD values at 550 nm wavelength.  These data allowed us to analyze the soils present in the atmosphere of the Amazon forest. Here some results of the ATTO project with our sun-photometer between August and September 2019.

Citation: Hassan Bencherif, Nelson Bègue, Damaris Kirsch Pinheiro, David Du Preez, Jean-Maurice Cadet, et al.. Investigating the Long-Range Transport of Aerosol Plumes Following the Amazon Fires (August 2019): A Multi-Instrumental Approach from Ground-Based and Satellite Observations. Remote Sensing, MDPI, 2020, Advances in Remote Sensing of Biomass Burning, 12 (22), pp.3846.

Read the article here!

If you want to discover or learn more about this major project, visit:

GAWPFR WMO reference

New AOD tracking technique by ESA with AERONET and the GAWPFR WMO reference

Keywords : Aerosols, Atmosphere, Sun/Sky/Lunar photometer, Meteorology

The World Meteorological Organization (WMO) has recognised the Word Optical Depth Research and Calibration Center (WORCC) as the primary reference center for Aerosol Optical Depth measurements. The WORCC is a section within the World Radiation Center at the Physikalisch-Meteorologisches Observatorium Davos (PMOD/WRC), located in Davos, Switzerland.

With its new QA4EO project, European Space Agency (ESA) wishes to obtain homogeneous results between the various passive monitoring networks of passive remote sensing of aerosol optical properties, presents in Davos and in France at the Observatoire de Haute Provence (OHP).

Consequently, a precision filter radiometer (PFR) travelling standard was installed at the European calibration site of AERONET to supply continuous traceability of aerosol optical depth measurements to the World reference maintained at Davos through a PFR Triad.

The precision filter radiometer was installed in July 2020 at the Observatoire de Haute Provence (OHP) on a solar tracker provided by the Laboratoire d’Observation Atmosphérique (LOA) next to our 4 sun photometers (CE318-T).

OHP’s platform, with four CIMEL Sun/Sky/Lunar photometers CE318-T and the PFR traveling (at the right of the picture).

The measurements of spectral solar irradiance during clear sky periods are used to retrieve AOD from our photometers with AERONET calibration and the PFR.

You can follow the comparison between these two instruments in real time on this web page. This real-time analysis allows for continuous monitoring and quality control of the measurements provided by these two devices.

Real-time monitoring of the measurement analysis of the two instruments on 24 March 2021 – Source:

After 6 months of comparison (August 2020 to January 2021) between the two networks, results have been very promising with an Aerosol Optical Depth difference of less than 0.01, corresponding perfectly to the WMO criteria for AOD traceability for 3 of its 4 channels. This shows that the results provided by CIMEL CE318-T photometers are in line with the WMO expectations and that CIMEL photometers may be used as an instrument of reference for other research projects.

Other projects are in parallel with this one such as the 19ENV04 project funded by EURAMET and the European Commission to extend the traceability of international unit systems through the characterization and calibration of our Sun/Sky/Lunar photometers from these networks (See more information here).

This collaboration between research institutes and the European metrology community will establish a consistent framework providing calibrations of our Sun/Sky/Lunar photometers with traceability to the SI as well as comprehensive uncertainty budgets that will be a necessary part of the data provided to the users and actors of these networks.

Kazadzis, S., Kouremeti, N., Nyeki, S., Gröbner, J., and Wehrli, C.: The World Optical Depth Research and Calibration Center (WORCC) quality assurance and quality control of GAW-PFR AOD measurements, Geosci. Instrum. Method. Data Syst., 7, 39-53,, 2018.

MAP-IO campaign

Ship-borne CE318-T photometer aboard the Marion Dufresne in the frame of the MAP-IO.

January 11th – March 8th2021

Since the beginning of January 2021, one of our CE318-T photometers is permanently embarked on the Marion Dufresne as part of the MAP-IO (Marion Dufresne Atmospheric Program – Indian Ocean) research programme.

The objective of a permanent installation of our photometer on the Marion Dufresne is to allow the measurement of atmospheric aerosols from mobile platforms, and to extend and automate the coverage of the AERONET network.

CE318-T CIMEL photometer aboard the Marion Dufresne (Credits : LACY/University of la Réunion)

In future campaigns, our photometer will be used mainly in the Southern Hemisphere and the Indian Ocean to measure the aerosol optical depth (AOD). The new campaign that has just started is the result of preparatory campaigns like OCEANET and SEA2CLOUD, during which the system has been tested, improved and validated.

Below, the preliminary results of the campaign obtained thanks to satellite data transmitted to the LOA/CNRS to measure spectral AOD, water vapour content, Ångström exponent, and sky radiance for AERONET.

Map of the first daytime recorded AOD (level 1.5) between 13 and 31 January 2021 (Source: Luc Blarel at LOA/CNRS/U. Lille).


  • To monitor long-term atmospheric changes in the Indian and Austral oceans regions which are very poorly documented (IR ACTRIS and ICOS).
  • To calibrate and validation data from satellites.
  • To understand better the ocean-atmosphere exchanges and regional pollution by improving and adapting and adapting the parametizations used in numerical weather and climate predition models over the Indian and the Austral oceans.

If you want to know more about this campaign click here !

Key words: Aerosols, Atmosphere, sun/sky/lunar photometer, Meteorology



ROSAS – A new BRDF photometer installed in Lamasquère by CESBIO

The Lamasquère site (France) is now equipped with a CIMEL 12 filters photometer (CE318-TU12) which measures direct and diffuse irradiation, and the directional reflectance of the surface (BRDF).

This system, installed in March 2021, is called RObotic Station for Atmosphere and Surface (ROSAS) and operates mounted on top of a 10 m high mast in a field on the agricultural area of Lamothe farm in Lamasquère (France). The CESBIO ROSAS station is thus the 3rd site of this type worldwide after the CNES station in La Crau (France) and the CNES/ESA station in Gobabeb (Namibia), and the first to characterize an agricultural vegetated surface, with seasonal and inter-annual variations of the cover.

The spatial and temporal heterogeneity of the surface of this new site makes it more suitable for the validation of surface reflectance (after atmospheric correction), than for the absolute calibration of satellite sensors, as it is the case for La Crau and Gobabeb. When the Lamasquère field crops become very green and dense, the surfaces are dark and the atmospheric correction errors have a strong impact on the reflectance estimates, and when the crops are mature or the plot is bare ground, the adjacency effects due to the nearby forest become strong. Such in situ measurements are thus of primary interest to CESBIO, CNES and the broader scientific community.

The data are automatically transmitted to CESBIO and CNES every hour via the mobile phone network (GPRS), and processed periodically to derive the filtered bi-directional reflectance distribution function (BRDF).

Here below, you can find the first BRDF measurements acquired a few days after the validation of the station:

Polar diagrams of surface reflectances measured by the ROSAS station in Lamasquère. The 0° azimut corresponds to observations towards the South. The top left image was taken in the morning, the top right around noon, bottom left in the afternoon, and bottom right later on after the arrival of clouds. The yellow dots indicate the position of the sun . The radius of the graph corresponds to the zenith angle, and the other dimension is the azimuth with regard to the North.


More information on :

RIMA NASA-AERONET network : Long-term monitoring of aerosol properties

UVa - Proyecto Aeropa

RIMA NASA-AERONET network: Long-term monitoring of aerosol properties

RIMA (Red Ibérica de Medida fotométrica de Aerosoles) is a scientific network for the long-term monitoring of columnar aerosol properties based on sun-photometer measurements. RIMA is federated to AERONET (AErosol RObotic NETwork), a NASA program in collaboration with the University of Lille (LOA). According to the AERONET aims, the scientific objectives of RIMA involve the characterization of aerosols for climate studies, the validation of satellite products and the synergies with other measurements and data correlation.

RIMA follows all AERONET protocols (calibration, measurements, data policy, etc.) and its sites and data are available through the AERONET web site. The key task of calibration and the network management are carried out by the Group of Atmospheric Optics of the University of Valladolid (GOA-UVa) and master instruments are calibrated at the high-mountain facility CIAI (Izaña Atmospheric Research Center, AEMET) in collaboration with PHOTONS and CIAI-AEMET. Large support is obtained from the AERONET (NASA) and PHOTONS (University of Lille). The calibration facility used by CIMEL for photometers in Izaña is important thanks to its pure sky and its absolute zero which allows a perfect calibration of those solutions since 2006.

A software named Caelis was recently developed by GOA as a service to the RIMA community with the aim to facilitate the network management and the control of the site instruments and measurements. This tool relies on a powerful relational data base which represents a great potential for the scientific work as well.

Keywords: Aerosols, AERONET, Calibration, Sun/Sky/Lunar Multispectral Photometer, Earth observation, Atmospheric monitoring, Satellite CAL/VAL

Acronyms :

  • CIAI: Centro de Investigación Atmosférica de Izaña
  • GOA-Uva: Grupo de Optica Atmosférica – Universidad de Valladolid
  • LOA: Laboratoire d’Optique Atmosphérique

Citation : Toledano, C. & Cachorro, Victoria & Berjón, Alberto & Frutos Baraja, A. & Fuertes, David & González, R. & Torres, Benjamin & Rodrigo, R. & Bennouna, Yasmine & Martín, L. & Guirado-Fuentes, Carmen. (2011). RIMA-AERONET network: Long-term monitoring of aerosol properties. Optica Pura y Aplicada. 44. 629-633.


ESA – New remote sensing tech on satellite for atmospheric measurements

VEGA Rocket

ESA – New remote sensing tech on satellite for atmospheric measurements


On September 3rd 2020, ESA has launched 42 small satellites aboard a Vega rocket from Kourou in French Guiana for the Copernicus Project.

This new type of satellites capable of measuring CO2 emissions to the nearest kilometer and pinpointing their origin.

One of these nanosatellites, PICASSO, carries remote sensing technology developed which will be used to undertake measurements in the upper layers of Earth’s atmosphere.

PICASSO stands for Pico-Satellite for Atmospheric and Space Science Observations and it’s the first CubeSat nanosatellite mission of the Royal Belgian Institute for Space Aeronomy.

Weighing only 3.5kg, it carries two measuring instruments for atmospheric research: A Visible Spectral Imager for Occultation and Nightglow (VISION) and a system to conduct plasma measurements in the ionosphere, the Sweeping Langmuir Probe (SLP).

This project of analysis and collection of satellite data will be carried out over 5 years. The aim is to obtain as much precise information as possible on the quantification of gases in the air.

We will be able to know exactly the real CO2 emission by country, cities and the origin of gases (if it’s anthropogenic or natural).

Thanks to this initiative, more and more surveillance systems will be sent into space over the next few years, which will help develop the market for remote sensing solutions.

Cimel will be part of this development by bringing additional data thanks to its photometers and LiDARs to help calibrate and validate data from satellites.

Credits: ESA-M. Pedoussaut


MOSAiC expedition for climateThe world largest polar expedition

1 SEPTEMBER 2019 – 31 OCTOBER 2020

The MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition is the largest polar expedition in history, involving hundreds of scientists from twenty countries for climate researches.

In September 2019, the German research icebreaker Polarstern set sail from Tromsø, Norway, to spend a year drifting through the Arctic Ocean, trapped in ice, to learn more about global warming and climate change.

This expedition is led by atmospheric scientist Markus Rex, and co-led by Klaus Dethloff and Matthew Shupe, MOSAiC is spearheaded by Alfred Wegener Institute, Hekmholtz Center for Polar and Marine Research (AWI).

The goal of the MOSAiC expedition is to require the closest look ever at the Arctic as the epicentre of worldwide warming and to realize fundamental insights that are key to raise understand global climate changes. The objective is to assess the impact of climate change on the region and on the world as a whole and, ultimately, to improve the performance of climate models in order to obtain more realistic projections.

In this expedition, TROPOS uses one of our Photometer (CE318-T) on the Polarstern to assist the scientists by measuring the atmosphere and providing data to help understanding the climatic model of the Arctic. (Follow the TROPOS campaign here).

MOSAiC expedition 2019
Scientific teams during MOSAiC campaign – December 15, 2019 (Alfred-Wegener-Institut / Esther Horvath)

The new and upcoming studies of the Poles are very important to understand our world, allowing new openings to new applications, new opportunities and new solutions for our environment.

All the results of the analysis will produce a flood of measurement data, which will be extremely valuable for the participating researchers and their peers around the globe, and also for humanity as a whole.

The MOSAiC expedition will end on October 12th after 390 days in extreme conditions for the 600 scientists who took turns in this incredible expedition in the Arctic.

Accordingly, the policy for MOSAiC data is based on a spirit of international cooperation, which all expedition participants expressly agree to adhere to. All the data is saved in the MOSAiC database wich is accessible by scientists of each country for detailed analyses and sharing it to the different members, states participating in this incredible and historical adventure.

If you want to follow the expedition, please check the MOSAiC website here or the Polastern Blog.

Image source: Alfred-Wegener-Institut / [Urheber/Fotograf]