The Ministry of Environment (ME), Ministry of Science and ICT (MSIT), and Ministry of Oceans and Fisheries (MOF) have first released on 18 November Asian air quality images from the Geostationary Environment Monitoring Spectrometer (GEMS) onboard the GEO-KOMPSAT-2B (GK-2B) satellite.

The images released today are the first results from the development project of the geostationary environmental satellite initiated in 2008. The satellite launched on 19 February 2020 and placed into the intented geostationary orbit on 6 March went through in-orbit testing (IOT) and now is in the test operation phase.

The images show levels of atmospheric pollutants including particulate matter, nitrogen dioxide, sulfur dioxide and ozone over Asia observed by GEMS during its IOT period.

They also provide information on temporal changes in generation, transport, and distribution of aerosol optical depth (AOD)* used as a proxy for particulate matter concentrations, nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3).

* Aerosol Optical Depth: An optical measure of the variations in solar transmittance caused by aerosols (i.e., particulate matter and fine dust)

Particularly on 9 September 2020, GEMS detected high levels of nitrogen dioxide emitted from large cities with heavy traffic (such as Seoul, Pyeongyang, Beijing, Shenyang, Osaka, Nagoya, etc.), industrial areas, and coal-fired power plants.

While traditional foreign low earth orbit (LEO) environmental satellites, OMI* and TROPOMI**, were difficult to fully observe the same areas due to cross track or thick clouds, GEMS can provide homogeneous information over the Asian region (see the figure below).

* OMI: Ozone Monitoring Instrument, launch in 2004 (the United States)

** TROPOMI: Tropospheric Monitoring Instrument, launch in 2017 (Europe)

GEMS also spotted the movement of an SO2 plume emitted from the Nishinoshima Volcano, Japan (6 August 2020), inflow of particulate matter into the Korean peninsula outside(20 October 2020), and high levels of total column ozone over Northeast China and Japan (6 August 2020).

This release presents that GEMS on a geostationary earth orbit (altitude of 36,000km) has comparable or better spatiotemporal* resolution of about 8 times per day and 3.5 × 8 km2 at Seoul than LEO satellites (altitude of 850 km) with similar air quality missions.

* Spatiotemporal resolution: the minimum observation area and the number of scans per day/hour

GEMS is the world's first environmental satellite on GEO that can observe its target area about 8 times everyday while the foreign LEO satellites do the same area only once per day.

In addition, GEMS has 11 times and twice better spatial resolution than the U.S. OMI and European TROPOMI, respectively.

* OMI (launch in 2004): One observation per day, 13 × 24 km2

* TROPOMI (launch in 2017): One observation per day, 7 × 7 km2

GEMS will make hourly measurements of atmospheric pollutants (particulate matter, sulfur dioxide, nitrogen dioxide, formaldehyde, ozone, etc.) average 8 times during daylight over the Asian region*.

* The GEMS domain covers about 20 Asian countries within the latitudes of 5°S to 45°N (Indonesia to Mongolia) and the longitudes of 80°E to 152°E (India to Japan).

It is expected that GEMS can make observations up to 10 times per day in summer and 6 times in winter.

The National Institute of Environmental Research (NIER) of the ME will determine the GEMS observation scenarios in a way that contains as much the Korean peninsula and Eastern China as possible, taking into account its effective observation area.

Moreover, the ME is planning to step up international cooperation in order to enhance the reliability of GEMS data and broaden their applications.

The 'Building the Pan-Asia Partnership for Geospatial Air Quality information (PAPGAPi) Project' has been initiated with the objective to share GEMS-derived information on air pollution including fine dust and climate change causing substances.

* Bangladesh, Bhutan, Cambodia, India, Indonesia, Laos, Mongolia, Myanmar, Nepal, the Philippines, Sri Lanka, Thailand, Vietnam

The International GEMS Validation Team kicked off in October 2020 will continuously conduct diverse research activities to validate and improve GEMS data products over the mission lifetime.

Environment Minister Cho Myung-Rae visited the Environmental Satellite Center of the NIER, ahead of the release, to be briefed on the data production procedure, regular observation scenarios, GEMS validation activities, and international cooperation projects.

He declared that "As demonstrated again by the GEMS imagery released today, air pollution is not a problem that can be solved by individual countries but an issue shared by the entire region. Therefore, the Korean government will promote multilateral international cooperation along with the bi-lateral efforts with China to improve air quality over Asia."

Chang Yoon-Seok, President of the NIER, said "Once the expert review is completed in the first half of next year, GEMS data products will be released on the Environmental Satellite Center website(nesc.nier.go.kr) sequentially, validated ones first, in the form of image files", and he added "GEMS measurements of air pollution over Asia will serve as robust scientific input to environmental policy making."

Attachments 1. Outline of the GK2B Project

        2. GEMS Development Project

        3. Temporal/Spatial Resolution of Major Air Quality Missions

        4. GEMS Images of Air Pollution

        5. GEMS Scan Coverage

        6. Q & A