Comparison between the ESFT and LBL simulation with enhanced SCIATRAN of orbital CO2 retrieval for High-resolution Satellite

The enhanced radiative transfer model SCIATRAN completes the simulation from the single point to the orbital data. There are 69 points locating at a global scale. The ESFT and LBL modes are implemented in the enhanced SCIATRAN for Medium-resolution Satellite (SCIAMACHY) and High-resolution Satellite simulations. A comparison of their spectra, accuracy and speed has been undertaken. For SCIAMACHY, the relative errors of O2 A-band (755-775 nm) and WCO2 band (1560-1680 nm) for ESFT and LBL (same sampling) are far less than 1%. The speed of ESFT mode is about 1.17 times faster than LBL mode for O2 A-band, about 5.24 times faster for WCO2 band. For High-resolution Satellite, the relative errors of O2 A-band and CO2 bands for ESFT and LBL are much less than 1%, and the speed increases to about 1.09 times for O2 A-band (759-769 nm) than LBL mode, about 3.83 times for WCO2 band (1568-1583 nm) than LBL mode. But the speed of LBL mode increases to about 47.55 times for SCO2 band (2043-2058 nm) than ESFT mode. This study provides a theoretical guide for the subsequent inversion of CO2 column concentration for High-resolution Satellite.