The progress of Chinese Carbon Dioxide Satellite (TanSat): observation design, Retrieval algorithm and validation network

Abstract:

The Chinese carbon dioxide observation satellite (TanSat) project is the national high technology research and development program. It is funded by the ministry of science and technology of the people’s republic of China and the Chinese Academy of Sciences. TanSat will monitor carbon dioxide in Sun-Synchronous orbit by a hyper resolution grating spectrometer – Carbon Dioxide Sensor. A wide field of view moderate resolution imaging spectrometer - Cloud and Aerosol Polarization Imager (CAPI) will measure the aerosol and cloud properties synchronously.

TanSat project turned to Critical Design Phase after Preliminary Design Review on June 2013, and it plan to finish Critical Design Review on December 2014 and launch on July 2016.

A multi-bands retrieval algorithm has been developed to approach XCO₂ with applying O₂A band observation to reduce aerosol and cirrus cloud influence. The state vector list has been modified from previous two-bands algorithm by adding aerosol model parameters, cirrus cloud model parameters and linear correction on O₂A bands. Application of TanSat XCO₂ retrieval Algorithm on GOSAT Observation (ATANGO) has been developed from multi-bands TanSat algorithm. GOSAT observation has been used in retrieval experiment of ATANGO. A preliminary inter comparison test has been carried out with the XCO₂ product of University of Leicester (UoL) full physics algorithm. The bias of 1.2 hPa (~0.1%) and 2.4ppm (~0.6%) of surface pressure and XCO₂ between ATANGO and UoL were indicated, and the standard deviation of 2.8hPa (~0.28%) and 1.23ppm (~0.3%) of surface pressure and XCO₂ between ATANGO and UoL were found.

The Ground-based observation network of XCO₂ in China was developed, which include three Fourier transform infrared spectroscopy (IFS-125) over Xinglong, Beijing, Shenzhen, and three Optical Spectrum Analyzers (OSA) over Shangdong, Hainan Island, and Dunhuang, with different latitude and background. The measurement spectrum has been investigated with a full physics optimal estimation algorithm and a DOAS like algorithm. The aerosol and cloud observation network measurement provided information on aerosol and cloud optical properties distribution in China, and it will be helpful to develop a more reliable priori data in future XCO₂ algorithm study.