Ice crystal morphological complexity and asymmetry parameter: Implications for light scattering measurements

The retrieval of asymmetry parameter often relies on comparison with light scattering models. Here, we present a model-free algorithm for retrieving the asymmetry parameter of ice crystals from polar nephelometer measurements. In addition, we introduce the so-called C$_p$ parameter for defining the degree of morphological complexity of ice crystals. The C$_p$ is defined in such a way that it measures the decay rate of coefficients for Legendre expansion of the angular scattering function. It was found that the C$_p$ parameter is strongly correlated with the distortion parameter of the ice crystal models. The effectiveness of C$_p$ is validated using a case study on rimed particles.