A spectroscopic method of monitoring the atmospheric CO 2 mixing ratio vertical profile from space is described. An experimental design is presented for a solar occultation mode with the O 2 A band in the visible region to retrieve pressure and temperature profiles first, and then several CO 2 bands in the infrared region at 4.3, 2.7, and 2.0 m to obtain CO 2 mixing ratio profiles. Instrument techniques considered are low resolution Fourier transform spectrometry and radiometry of various

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... dths. Simulations indicate that the precision of the pressure, temperature, and CO 2 mixing ratio measurements for an altitude region 30 -10 km are less than 1%, 1 K, and 1%, respectively, for the case of the Fourier transform spectrometer and approximately 1%, 1 K, and 2% for the case of the radiometer. With careful experimental design, measurements can be made with better precision and also can extend below 10 km. This inferred precision of CO 2 may be considered to be good enough for investigating atmospheric dynamics when CO 2 is used as a tracer and also for measuring spatial and temporal variations of CO 2 mixing ratios in the range of 0.5-6.5% of 350 parts per million by volume in the troposphere and the lower stratosphere.