Accurate Absolute Measurements of Liquid Water Content (LWC) and Ice Water Content (IWC) of Clouds and Precipitation with Spectrometric Water Raman Lidar

Abstract A detailed description is given of how the liquid water content (LWC) and ice (IWC) can be determined accurately absolutely from measured Raman spectra clouds. All instrumental spectroscopic parameters that affect accuracy water-content measurement are discussed quantified; specifically, these effective absolute differential backscattering cross section vapor , molecular efficiencies η liq frozen microparticles, respectively. The latter two following rigorous theoretical approaches combined with Lidar for Atmospheric Moisture Sensing (RAMSES) measurements. For this includes a new experimental method assumes continuity number molecules across vertical extent melting layer. Examples measurements presented, including supercooled liquid-water clouds layers. Error sources discussed; one effect stands out interfering fluorescence by aerosols. Aerosol effects calibration issues main reasons why spectral required quantitative LWC IWC. presented study lays foundation cloud microphysical investigations evaluation models or data products other instruments. As first application, IWC retrieval methods evaluated based on either lidar extinction radar reflectivity While lidar-based retrievals show unsatisfactory agreement RAMSES measurements, radar-based which used in Cloudnet project performs reasonably well. On average, retrieved agrees within 20% to 30% (dry bias)