Mesure de la pression et de la température atmosphériques par absorption différentielle lidar: influence de la largeur d'émission laser

Tropospheric pressure and temperature could be deduced from the measurement of the molecular oxygen optical thickness in the A band centered at 762 nm. A detailed study of the accuracies of these measurements is presented, taking into account the nonmonochromaticity of the laser emission, the experimental uncertainties, and the atmospheric perturbations which lead to uncertainties in the mathematical derivation. Relative accuracies of 0.2 percent on the pressure and 0.4 percent on the temperature could be obtained using operational lidar systems. The vertical range is from 2 km to 3 km with a spatial resolution of 100 m and an integration time of the order of 1 min. It is shown that the assumption of the monochromaticity of the laser emission requires the spectral width and the accuracy for the absolute frequency of the laser line to be both less than a few tenths of a gigahertz