Atmosphere and Ocean-Surface Observations by GCOM-C (SHIKISAI)

抄録

SHIKISAI, the Global Change Observation Mission-Climate (GCOM-C) satellite, was launched on 23 Dec. 2017 and began global observation with a Second-generation Global Imager (SGLI) on 1 Jan. 2018. SGLI has seventeen channels from near-ultraviolet (NUV, 0.38 m) to thermal infrared (12 m) wavelengths and two polarization channels at the red and nearinfrared wavelengths with a spatial resolution of 250 m or 1 km and a swath width of 1150 km or 1400 km. The goals of GCOM-C are to continuously monitor changes in the global environment and acquire the knowledge needed to improve our prediction of the earth-system environment. For example, the unique SGLI channels and spatial resolution enabled us to observe the following atmosphere and ocean surface phenomena. Thick aerosols from the wildfires in eastern Siberia were characterized by SGLI polarimetry and NUV channels, which are advantageous in detecting small-particle aerosols and optically absorbing aerosols. The 250-m resolution multi-channel observation enabled us to evaluate the spectral characteristics of water-leaving reflectance at patches of high chlorophyll-a concentration in coastal areas, including various kinds of red tide. Pumice rafts produced by a submarine volcano, Fukuoka-no-ba, were detected by the SGLI 250-m resolution images in 2021. We derived the fine resolution ocean surface current using pairing sensors of similar spatial resolution with tens of minutes time lag. GCOM-C/SGLI can be expected to play a role in the earth system's observation networks by continuing the observations over more periods than the planned 5-year lifetime.