The Status of development activities for Geostationary Environment Monitoring Spectrometer(GEMS)

The GEMS project has been underway since 2008 to monitor the trace gases, NO2, SO2, HCHO, O3 and AOD. Currently, GEMS has been installed on the GK2B, and environment testing at satellite level is underway. The GK2B satellites equipped GEMS will be launched in Guiana before March 2020 using the Ariane 5.

GEMS coverage is about 75°E - 114°E and 5°S - 45°N, and spatial resolution is 8 × 7 km² at Seoul. GEMS observes ultraviolet-visible range between 300nm and 500nm with 0.6 nm spectral resolution, and takes images hourly intervals in the daytime, alternating with the GOCI-2 (Geostationary Ocean Color Imager-II) every 30min.

Main products (O₃, HCHO, NO₂, SO₂, AOD, etc.) of GEMS are retrieved via Differential Optical Absorption Spectroscopy (DOAS) (NO₂, SO₂, HCHO, and cloud), Optical estimation (AOD, O₃ profile, and O₃ total) using UV-Vis hyper-spectral earthshine radiance.

We expect that GEMS will calculate atmospheric contents of trace gases and aerosol optical depth and be able to provide fundamental data for the global monitoring and improvement of the environment.

In addition, we anticipate GEMS to be utilized in air quality prediction models and contribute to the increased accuracy of forecasts and warnings that are needed for the avoidance of air pollution, thus, enhancing the quality of life of people. Also, we expect that GEMS will potentially be able to contribute in the development of a clean air environment globally.

This presentation assessed the role and the potential of GEMS in air quality monitoring and addressing climate change, the current development situation of GEMS and preparation for data production.