Spectrometric fluorescence and Raman lidar: absolute calibration of aerosol fluorescence spectra and fluorescence correction of humidity measurements

Abstract. RAMSES is the operational spectrometric fluorescence and Raman lidar at Lindenberg Meteorological Observatory. It employs three spectrometers, with UVA spectrometer (378–458 nm spectral range) being latest to be implemented in 2018. The extends measurement range shorter wavelengths than previously accessible, its water vapor measurements can corrected for effects. First new experimental setup of near-range receiver, which integrates spectrometer, described. Then it detailed how absolutely calibrated spectra are merged those obtained second (440–750 range). part this study dedicated effect aerosol on lidars. When aerosols present, a fluorescence-induced error always arises therefore requires thorough analysis, even though particularly significant (in relative terms) only when atmosphere dry, signal strong, or bandwidth detection channels wide. For moisture method introduced that effectively eliminates systematic error. However, increase trueness comes expense precision. investigations further show an accurate correction impossible not equipped but single receiver channel only, least biomass burning aerosol, because given backscatter coefficient wavelength auxiliary channel, induced humidity vary widely due changing shape spectrum, depends type atmospheric state possibly also other factors.