Initial results of GOSAT TANSO calibration

Abstract

Greenhouse gases Observing SATellite (GOSAT) is a Japanese mission to observe greenhouse gases, such as CO 2 and CH 4 , from space with a Fourier transform spectrometer and a push broom imager. The GOSAT was launched on January 23, 2009. The initial functional check-out phase was completed on April 10 to confirm the on-orbit performance. The initial calibration and validation phase was completed on July 30 in the following 3 months to acquire observation data at calibration and validation sites. The initial calibration was evaluated on accuracies of radiometry, geometry and spectrometry by using acquired data. The results were reflected to the improvement of the Level 1 algorithm and the products. The initial calibrated Level 1 products have been already released to the GOSAT research PIs in August.

Calibration of operational GOSAT Level 1 products

“…The spectral axis accuracies can be evaluated by 2 independent methods, solar Fraunhofer lines and atmospheric absorption lines. Spectral axis of both sunlight and atmosphere evaluations were resulted in similar shifts in calibration and validation phase [3]. The solar Fraunhofer line has a sharp structure to determine the line position accurately.…”

“…The Level 1 algorithm was developed by using the evaluation of the PFT data [2]. After the launching, the observation data was evaluated on orbit by onboard and vicarious calibration methods in the initial calibration and validation phase [3]. The results were reflected to improvement of the Level 1 algorithm for providing the initial calibrated Level 1 products.…”

Research on Calculation Method of On-Orbit Instrumental Line Shape Function for the Greenhouse Gases Monitoring Instrument on the GaoFen-5B Satellite

“…This involves measuring the ILSF by selecting prominent gas absorption lines or laser wavelengths within the working spectral range. For on-orbit ILSF determination, laser diodes are commonly chosen as light sources [18][19][20], sharing the same principles as tunable lasers. Another option is to use the solar spectrum, although adjustments to parameters such as the distance from the Sun to the Earth and solar activity cycles are necessary [21].…”