资源环境科技发展态势分析平台

The microphysical characteristics of deep convective storms are a critically important, yet difficult aspect of storm morphology to observe in situ. These observations play a large role in several areas of ongoing research, but detailed observations in key portions of clouds do not exist with the currently available measurement platforms. To facilitate these observations, a balloon-borne particle imaging device known as the PArticle Size, Image, and Velocity (PASIV) probe was developed at the National Severe Storms Laboratory, which is capable of measuring particle counts on scales as small as 50m. The videosonde observations from the PASIV showed that precipitation particle counts change rapidly between analysis layers, sometimes by as much as a few orders of magnitude (10(2)-10(4) in adjacent layers), and radar reflectivities calculated directly from observed particle size distributions agree with mobile radar measurements. Furthermore, the observations allow the distributions to be partitioned into various particle types, which sheds light on which particles are dominating the radar signal at various times. These distributions per particle type, and their associated mixing ratios, agree with independent model analysis. Additionally, single-, double-, and triple-moment parameterized particle size distribution functions are fit to various layers, with the general result that ice particles are easily represented by exponential distributions while rain is better fit with a gamma distribution. The parametric fits for ice and rain distributions found here support previous work and some portions of modeled microphysics, but also suggest room for improvement when deciding which schemes to use with cloud modeling.

Plain Language Summary A microphysics instrument capable of measuring the number, size, shape, and composition of particles inside thunderstorms has been developed that flies on a weather balloon. The observations collected are compared to radar observations and some aspects of computer models that validate what these other tools are seeing and show room for improvements. These observations are providing a unique and unprecedented look at the details of in situ particle concentrations. Understanding of the processes responsible for the formation and maintenance of these particles can lead to advances in forecasting ability and real-time decision making.