Three-wavelength CO₂ differential absorption lidar for atmospheric temperature profiling at 1.57  µm

We propose a three-wavelength CO₂-DIAL operating at 1.57 µm for lower-tropospheric temperature profiling. The method retrieves temperature and CO₂ number density simultaneously by matching two independent CO₂ densities derived from different absorption pairs within a self-consistent retrieval framework. Sensitivity analysis shows that the effective absorption cross section is nearly independent of aerosol scattering ratio, enabling temperature retrieval without the aerosol corrections. Field observations demonstrate temperature uncertainty better than 0.8 K from 0.4 to 3.1 km altitudes, with a 0.3 km vertical and 30 min temporal resolutions. Water-vapor interference is negligible (<0.05K), confirming the robustness of the approach for lower-tropospheric temperature measurements.