A statistical study of meteoroid fragmentation and differential ablation using the Resolute Bay Incoherent Scatter Radar

There has been much interest in the meteor physics community recently regarding the detailed processes by which the meteoroid mass flux arrives in the upper atmosphere. Of particular interest are the relative roles of simple ablation, differential ablation, and fragmentation in interpretation of the meteor events observed by the high-power large-aperture (HPLA) radars. An understanding of the relative roles of these mechanisms is necessary to determine whether the considerable meteor mass flux arriving in the upper atmosphere arrives mostly in nanometer dust/smoke (via fragmentation) or atomic form (via ablation), which in turn has important consequences in understanding not only the aeronomy of the region but also the formation and evolution of various upper atmospheric phenomenon such as Polar Mesospheric Summer Echoes. Using meteor observations from the newly operational Resolute Bay Incoherent Scatter Radar (RISR), we present the first statistical study showing the relative contribution of these mechanisms. We find that RISR head echoes exhibited ∼48% fragmentation, ∼32% simple ablation, and ∼20% differential ablation. We also report existence of compound meteor events exhibiting signatures of more than one mass loss mechanism. These results emphasize that the processes by which the meteoroid mass is deposited into the upper atmosphere are complex and involve all three mechanisms described here. This conclusion is unlike the previously reported results that stress the importance of one or the other of these mechanisms. These results will also contribute in improving current meteoroid disintegration/ablation models.