| The University of Wyoming King Air (UWKA) platform with its airborne profiling lidars provided a unique opportunity to investigate the vertical structure and evolution of atmospheric bores during the Plains Elevated Convection at Night (PECAN) field campaign in summer 2015. One particularly impressive bore with striking roll clouds was sampled on June 20 from the time the leading wave first pulled away from the cold pool, where over 10 m s-1 updrafts were encountered, through the early dissipative stage in which the leading wave began to lose amplitude and speed. Striking roll clouds formed in wave crests and wave energy was detected to about 4.5 km AGL.;Phase relationships observed at flight level were different from those at the surface. In particular, enhanced front-to-rear winds, cooler air, and negative pressure perturbations (p') prevailed in crests. The latter probably were non-hydrostatic, caused by strong horizontal vorticity. Flight level winds above the bore fluid persistently were front-to-rear. Surface measurements late in the bore's lifecycle, just after sunrise, indicated four waves with a northerly wind direction in crests and a maximum p' value of +2 mb in the first crest, followed by slight warming. Ground-based profiling measurements showed mixing and moistening of the boundary layer. A wave trapping analysis indicated a negative Scorer parameter region due to flow reversal at mid-levels, providing significant curvature above the stable boundary layer. The observed bore strength of 2.4-2.9 and speed of 15-16 m s-1 agree well with values predicted from hydraulic theory.;Preliminary analyses of the July 11 and July 15 bore cases are also included in this study with the intention of providing a basis for future work. |
