Measurement of Pressure-Induced Broadening and Shift Coefficients of Carbon Dioxide Absorption Lines around 1.6 µm for using Differential Absorption Lidar

Abstract

A precise measurement of the vertical profiles of carbon dioxide is required for reducing the uncertainty in the carbon budget. In order to achieve measurements of the vertical CO2 distribution with an uncertainty better than approximately 4 ppm, a precise knowledge of the pressure-dependent broadening and shift coefficients of CO2 absorption lines is indispensable. In this paper, we report the measurement of air pressure-induced shift coefficients for eight absorption lines at around 1.57 µm. On average, the pressure shift coefficients are -0.30 MHz/Torr for pure CO2 and -0.24 MHz/Torr under an air-mixed condition.