On the determination of scale ranges for precipitation fields

To test some recent theories on the nature of precipitation structure, data were collected using radar and a newly developed ''sonic'' gauge to investigate precipitation variability at small scales. Results show that the structure of precipitation below a few tens of meters has very different statistics than at larger scales. Interpretation of vertically pointing radar data suggests that, at small scales, a mixing-like process occurs because of the differential fall speed of hydrometeors, which results in the destruction of small-scale structure. It is also shown that convection in the melting layer seems to recreate some of the structure that had been lost as snow fell. Finally, over scales of meteorological interest, at least four distinct regimes in precipitation variability can be identified.