Size distribution of hydrometeors through the melting layer

Hydrometeor size and velocity distributions and particle number flux densities are measured with an optical spectrometer within the melting layer of stratiform precipitation. These data are compared to raindrop size measurements with a disdrometer below the melting layer. Comparing the hydrometeor number flux densities, the following conclusions can be made: the number flux density of snowflakes just above the melting layer corresponds 1:1 to the number flux density of raindrops just below the melting layer. Furthermore, strong evidence is found for aggregation of hydrometeors within the upper part of the melting layer and breakup within the lower part.