Further evidence for superterminal raindrops

Abstract

A network of optical disdrometers (including laser precipitation monitors and a two-dimensional video disdrometer) was utilized to determine whether the recent reports of "superterminal" raindrops were spurious results of drop breakup occurring on instrumentation. Results unequivocally show that superterminal raindrops at small (less than 1 mm) sizes are ubiquitous, are measurable over an extended area, and appear in every rain event investigated. No evidence was found to suggest that superterminal drops are the result of drop breakup due to impact with the measurement instrument; thus, if the superterminal drops are the result of drop fragmentation, this fragmentation happens in the ambient atmosphere during all rain events measured in this study. The ubiquity of superterminal drops at small drop sizes raises natural questions regarding rain accumulation estimations, estimates of drop size distributions, and erosion characterization. Key Points Superterminal drops are realSuperterminal drops are not the result of instrument splashingA large fraction of drops less than 1 mm in diameter appears to be superterminal