Introducing the geostationary environment monitoring spectrometer

Abstract

To consistently observe deteriorating air quality over East Asia, the National Institute of Environmental Research, Republic of Korea, is planning to launch an environmental observation sensor, the Geostationary Environment Monitoring Spectrometer (GEMS), onboard the GK-2B satellite (a successor to the GeoKOMPSAT-1) in late 2019. GEMS is a hyperspectral spectrometer that covers the ultraviolet-visible range (300 to 500 nm) with full-width at halfmaximum of 0.6 nm. It has been designed for the observation of air pollutants and short-lived climate pollutants. GEMS captures images at hourly intervals in the daytime, alternating with the Geostationary Ocean Color Imager-II every 30 min. Over the Seoul Special Metropolitan area, South Korea, the spatial sampling resolution of GEMS is 3.5 × 8 km (north-south and east-west, respectively). There are 16 baseline products, including aerosol optical depth and the vertical column density of trace gases such as nitrogen dioxide, sulfur dioxide, formaldehyde, and ozone. Research continues into additional applications (e.g., ground-level concentrations and emissions). © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

New Era of Air Quality Monitoring from Space: Geostationary Environment Monitoring Spectrometer (GEMS)

“…High-temporal-and high-spatial-resolution observations of aerosol properties have been available from geostationary Earth orbit (GEO) instruments: the Meteorological Imager (MI) and the Geostationary Ocean Color Imager (GOCI) on board the Geostationary Korea Multi-Purpose Satellite (GK)-1, also known as Communication, Oceanography and Meteorology Satellite (COMS), and, more recently, from the AHI over Asia (Kim et al 2008;Kim et al 2016;Choi et al 2016;Choi and Ho 2015;Lim et al 2018). Long-term validation of the GOCI aerosol optical depth (AOD) indicates good agreement with ground-based Aerosol Robotic Network (AERONET) measurements, with correlation coefficients of ~0.9 (M. Choi et al 2018). A long-term decreasing trend in AOD over East Asia beginning in 2011 has been identified (e.g., Kim et al 2017).…”

“…Following the increasing interest in AQ in Asia, the GEMS project was initiated by the NIER of Korea in 2008 to establish space-based measurements of AQ at high temporal and spatial resolution (W. J. Choi et al 2018). Since then, feasibility studies for user requirements, conceptual designs, and science algorithm sensitivity studies have been collaboratively conducted by the Korea Aerospace Research Institute (KARI), NIER, and GEMS science team.…”

Spectral Calibration Algorithm for the Geostationary Environment Monitoring Spectrometer (GEMS)

“…Scientific data are then passed to a Consultative Committee for Space Data System encoder (protocol 133.0-B-1) and delivered to the GK2B spacecraft over the broadband SpaceWire data line. Choi et al 2019 [3] provide more details on the GEMS instruments.…”

“…They are collocated at 128.2° E over the equator, where the current GK-1 satellite is stationed. While the GK-2A satellite is dedicated to weather monitoring with a high-performing imaging instrument (16-channel imagers in the visible and infrared bands [1]), the GK-2B satellite is for ocean and environmental observation [2][3]. The ocean mission is a follow-on mission of the current Geostationary Ocean Color Imager (GOCI) of the GK-1 with an improved GOCI-II spectrometer, while the environmental mission is a new in the geostationary.…”

“…The ocean mission is a follow-on mission of the current Geostationary Ocean Color Imager (GOCI) of the GK-1 with an improved GOCI-II spectrometer, while the environmental mission is a new in the geostationary. The GEMS is the key instrument for the environmental mission, as it provides information on trace gases such as ozone, nitrogen dioxide, sulfur dioxide, and formaldehyde, as well as aerosols [2][3]. Geostationary orbit allows the GEMS instrument to provide unprecedented spatio-temporal resolution of air quality information, at least eight times per day with about 3.5 km × 8 km spatial resolution from space.…”