ISRO's OCM-3 AOD & EOS-06: Transforming India's Air Quality Insight

By Girish Linganna

Mar 5: ISRO has developed and validated a new instrument, the Ocean Colour Monitor (OCM-3) Aerosol Optical Depth (AOD) product, which aids in deciphering the intricate variations in air quality throughout India. Utilizing the innovative SAC AErosol Retrieval (SAER) algorithm and data from the EOS-6 satellite, this advanced tool offers a refined approach to observing and analyzing air pollution in India. ISRO confirmed its effectiveness through a tweet on the X platform yesterday.

The Indian Space Research Organisation (ISRO) successfully launched nine satellites, including an Earth Observation Satellite (EOS-06), into various orbits using the agency's Polar Satellite Launch Vehicle (PSLV-C54) on the 26th of November 2022.

EOS-06 represents the third generation in the Oceansat series,with mass of 1117 kgs , offering ongoing services similar to Oceansat-2 but with improved payload capabilities. This satellite is equipped with four key instruments: the Ocean Color Monitor (OCM-3), Sea Surface Temperature Monitor (SSTM), Ku-Band Scatterometer (SCAT-3), and ARGOS. Oceansat-2, launched in September 2009, was designed to observe the world's oceans, continuing to gather ocean color data along with global wind vector information and contributing to the study of the lower atmosphere and ionosphere.

EOS-06 is designed to collect ocean color data, sea surface temperature, and wind vector information for use in oceanographic, climatic, and meteorological studies. The satellite is also aimed to support the creation of value-added products like potential fishing zones, utilizing chlorophyll, sea surface temperature, and wind speed, as well as terrestrial geophysical parameters.

The Ocean Colour Monitor (OCM-3) Aerosol Optical Depth (AOD) product is now available to researchers and students on "Meteorological and Oceanographic Satellite Data Archival Center (MOSDAC)" following their official registration. ISRO invites scholars to explore air quality dynamics in unprecedented detail with this data repository. It acts as a standard for air quality simulation models, offering critical information for academics and decision-makers aiming for a more sustainable and healthier environment.

This progress is made possible through the impressive 1-kilometer spatial resolution of the OCM-3 aboard the EOS-6 satellite. The EOS-6, which was launched in 2022, comes fitted with an advanced OCM sensor. This represents a major advancement in our capability to observe atmospheric aerosols, which are tiny particles suspended in the air that can affect air quality and climate. This high level of detail enhances our understanding of air pollution patterns and their impact on the environment.

A 1 km spatial resolution means the satellite can distinguish features on the Earth's surface that are as small as 1 kilometer apart, providing detailed images and data for analysis.

The OCM-3 AOD product offers new and detailed views of aerosol levels over India.It thoroughly examines the tiny particles floating in the air, helping scientists understand air quality changes accurately. Its detailed data shows how tiny dust and pollution particles (PM2.5/PM10) move and spread over big cities, providing a clearer picture of air pollution.Outside of India, the OCM-3 AOD product is used around the world to keep an eye on aerosols from various sources, like fires in South Asia and wildfires in Canada, helping us understand how these particles cover areas globally.

PM 2.5 and PM 10.0 refer to particulate matter that is 2.5 micrometers and 10 micrometers in diameter or smaller, respectively. These tiny particles are suspended in the air and can be harmful to health, with PM 2.5 being able to penetrate deep into the lungs and even enter the bloodstream.

Aerosols are tiny particles or droplets in the air that can come from natural sources or human activities.

The OCM-3 AOD product has been thoroughly checked and confirmed to be accurate by comparing it with measurements taken on the ground. Over four months, from January to April 2023, the data from the satellite was matched with real measurements from AERONET stations across India, proving that the satellite's data is reliable.

Aerosols are tiny solid or liquid particles floating in the air that can influence the planet's climate, cloud characteristics, the quality of the air we breathe, and our health.Aerosol Optical Depth or Thickness (AOD/AOT) measures how much aerosols are present in a column of the atmosphere from the ground up.The Aerosol Robotic Network (AERONET) across India allows for the comparison of aerosol trends over different years.Thorough checks of the OCM-3 AOD product in India and neighboring South Asian countries have demonstrated great accuracy, with match levels reaching 0.8. This means the satellite data closely aligns with actual measurements, where 0.8 indicates a very strong agreement.

Recent studies have shown a significant rise in aerosol levels after October 13, 2023, especially over the Indo-Gangetic Plain. Delhi, in particular, has very high aerosol levels, highlighting the lasting effects of pollution around and after the Diwali festival.In mid-December, there was a slight improvement in air quality, but then aerosol levels went up again in mid-January 2024.The AOD measurements and fire information, together with air path analysis, prove there are many fires happening. This shows that burning leftover crops is a major cause of bad air pollution.

Therefore, the OCM-3 AOD provides a detailed view towards creating a future where each breath reflects advancement. Interested parties are invited to sign up at MOSDAC to explore and help improve accurate air quality tracking,says ISRO.




(The author Girish Linganna of this article is a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. You can reach out to him at:



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Title: ISRO's OCM-3 AOD & EOS-06: Transforming India's Air Quality Insight

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