Tropospheric NO<sub>2</sub> measurements using a three-wavelength optical parametric oscillator differential absorption lidar

Abstract. The conventional two-wavelength differential absorption lidar (DIAL) has measured air pollutants such as nitrogen dioxide (NO2). However, high concentrations of aerosol within the planetary boundary layer (PBL) can cause significant retrieval errors using only a DIAL technique to measure NO2. We proposed new obtain more accurate measurements NO2 three-wavelength based on an optical parametric oscillator (OPO) laser. This study derives equations necessary retrieve vertical profiles in troposphere. Additionally, two rules optimum choice three wavelengths applied are designed help increase differences cross-sections and reduce interference. relative uncertainties caused by extinction, molecular gases other than gas interest backscattering calculated (438 439.5 nm) (438, 441 techniques. extinction reduced less 2 % those when technique. Moreover, uncertainty analysis indicates that fluctuation presents concentration which were obtained HU (Hampton University) OPO DIAL. As first step assess accuracy profiles, we compared simulated data from Weather Research Forecasting Chemistry (WRF-Chem) model. comparison suggests retrieved with have similar structure magnitudes typically ±0.1 ppb modeled profiles.