Fractal geometry of aggregate snowflakes revealed by triple wavelength radar measurements
Stein, T. H. M., Westbrook, C. D. and Nicol, J. (2015) Fractal geometry of aggregate snowflakes revealed by triple wavelength radar measurements. Geophysical Research Letters, 42 (1). pp. 176-183. ISSN 0094-8276
To link to this article DOI: 10.1002/2014GL062170
Radar reflectivity measurements from three different wavelengths are used to retrieve information about the shape of aggregate snowflakes in deep stratiform ice clouds. Dual-wavelength ratios are calculated for different shape models and compared to observations at 3, 35 and 94 GHz. It is demonstrated that many scattering models, including spherical and spheroidal models, do not adequately describe the aggregate snowflakes that are observed. The observations are consistent with fractal aggregate geometries generated by a physically-based aggregation model. It is demonstrated that the fractal dimension of large aggregates can be inferred directly from the radar data. Fractal dimensions close to 2 are retrieved, consistent with previous theoretical models and in-situ observations.