Validation and Analysis of GOSAT XCO2 Measurements by TCCON Sites
The data from 18 sites of TCCON are used for the validation of GOSAT XCO2 products from 2009 to 2017, which show a consistency between satellite data and groundbased measurements. Biases between the satellite data and groundbased measurements in East Asia, North America, Europe and Oceania are 2.23±2.69, 2.19±2.19, 2.01±2.49， 1.59±1.79 ppm, respectively, and the correlation coefficient is not less than 0.75. The accuracy of satellite products is higher in the range of 30°S-60°N, but slightly lower in high latitudes. In addition, authors also use GOSAT L2 XCO2 products to analyze the change of global atmospheric CO2 in longterm sequence. The results show that the concentration of global atmospheric CO2 shows a continuous upward trend from 2009 to 2017, and the global average annual growth rate is 2.22 ppm·a-1. There are some fastgrowing countries and regions, including China, the United States, India, and Africa. Influenced by natural emissions of El Ni〖AKn~D〗o, the concentration of atmospheric CO2 grew the fastest in 2016, with the growth rate being more than 3 ppm·a-1.