The lidar data acquisition system was modified to continuously record these parameters with each lidar scan. This modified system has been operational since August 1998. The lidar calibration was then empirically adjusted so that the aerosol scattering coefficients derived from the lidar agreed with those measured with a nephelometer. An example of our preliminary measurements is shown in figure 1. The panel shows the aerosol phase function measured with a polar nephelometer.
Measurements show enhanced forward scatter, which is typical of large salt aerosol.
Measurements above 155 degrees are not valid. The right panel shows a time series of scattering versus time. Lidars also suffer from a near field effect in which light is not focused on the detector. In order to characterize this effect for our system, we have used a spectralon target to measure the near field response as a function of distance. The results are shown in Figure 2, along with a theoretical response calculated for a Cassegrain telescope using the parameters for our 28 cm Celestron.