Airborne remote sensing by lidar complements in-situ measurements by adding an extra, vertical dimension along the flight path. Lidar, which measures light back-scattered from atmospheric particles, provides insight into a number of questions about aerosol properties in the atmosphere, e.g., detrainment from clouds, vertical layering and the formation of new particles. In this study we utilize airborne lidar and in situ aerosol measurements obtained during EPIC2001 to derive a methodology with whichto address these questions.
Lidars only measure relative backscatter, a parameter that is related to the actual backscatter coefficient of aerosols and varies with concentration, size and composition. The conversion of relative to actual backscatter requires calibrations that cannot be done in the laboratory, but must be devised through other methods, such as comparisons with in situ measurements. The technique discussed in this presentation utilizes the airborne measurements from multiple optical spectrometers to derive backscatter profiles during aircraft soundings. These profiles are fit to lidar profiles made at low level prior to the sounding. The best-fit coefficients provide the calibration factor that will be used to convert lidar measurements to backscatter coefficients, an optical parameter that is physically related to aerosol properties, as is discussed in the presentation.