Development of an aerosol retrieval algorithm and aerosol properties from GOSAT-2/TANSO-CAI-2

Makiko Hashimoto,  JAXA,  hashimoto.makiko@jaxa.jp (Presenter)
Chong Shi,  NIES,  shic87@gmail.com
Hideaki Takenaka,  Chiba University,  neurolink.sys@gmail.com
Teruyuki Nakajima,  NIES,  terry-nkj@nifty.com

Greenhouse gases Observing Satellite-2 (GOSAT-2) was launched on October 29th, 2018. GOSAT-2 has two sensors, TANSO-FTS-2 (FTS-2) and TANSO-CAI-2 (CAI-2) for greenhouse gas and cloud-and-aerosol observation, respectively. CAI-2 performs two-directional observation in forward and backward directions and makes an observation at ten bands composed of seven wavelengths at 340, 380, 443, 550, 674, 869 and 1630 nm. The spatial resolution (IFOV) is 920 m at a wavelength of 1630 nm and 460 m at the other wavelengths. CAI-2 is characterized by having two ultraviolet (UV) bands at 340 and 380 nm, which soot, or black carbon (BC), and dust particles have strong light absorption. It is expected that the retrieval accuracy of light absorption characteristics of aerosols can be improved. Particle size information also can be estimated from the visible and near infrared bands. Using these bands data of CAI-2, aerosol optical thickness (AOT), Ångstrom exponent (AE), BC volume fraction (BCF) and equivalent value of PM2.5 (i.e., fine particle amount) are derived.
It is important to understand the aerosol optical properties in urban areas, which is the main source of anthropogenic aerosols. We have developed an aerosol retrieval algorithm called the multi-wavelength and multi-pixel method (MWPM) (Hashimoto and Nakajima, 2017). The method was developed so that aerosol characteristics can be derived with high accuracy even in areas where the ground surface reflectance is non-uniform like urban areas. MWPM has been accelerated by neural network-based method called EXAM (Takenaka et al., 2011). We also have developed an algorithm using multiple pixels over ocean called SIRAW (Shi et al., 2019).
The algorithm has been applied to CAI-2, and aerosol optical properties, fine and coarse particle AOTs, AE, SSA and BCF has been retrieved. We show the result of aerosol properties and comparison with aerosol properties by ground-based observation such as AERONET and SKYNET, and discuss the result and algorithms for modification of the algorithm in the future.

Presentation: Talk_Hashimoto_45_25.pdf 

Presentation Type: Talk

Session: 2.1 Retrieval algorithms and methods for inter-instrument and product Cal/Val

Session Date: Tuesday (6/15) 9:00 AM