Are high concentrations of small particles in cirrus consistent with remote sensing observations?

Aircraft in situ data consistently shows sub 100 micron particle concentrations in excess of 1 per cc in middle latitude and tropical cirrus. Observed particle size distributions frequently demonstrate bimodality with a small particle mode dominating the extinction and even the water content of most cirrus. Some doubt has been cast on these measurements, however, due to possible shattering of ice crystals on probe inlets and aircraft surfaces. We contend that the occurrence of significantly bimodal particle size distributions must be consistent with remote sensing measurements. Using data from the ARM MMCR and Raman lidar we implement a cloud property retrieval algorithm that has been developed with an assumption of a bimodal particle size distribution to explore this issue. Results from examining 1 year of data at SGP will be presented.