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 sho w that the structure of precipitation below a few tens of meters has v ery different statistics than at larger scales. Interpretation of vert ically pointing radar data suggests that, at small scales, a mixing-li ke process occurs because of the differential fall speed of hydrometeo rs, which results in the destruction of small-scale structure. It is a lso 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 precipi tation variability can be identified.