Variations in the microphysical structure of stratiform regions of BAMEX MCSs from optical array probe measurements and high-resolution radar observations

During the Bow Echo and Mesoscale Vortex Experiment (BAMEX), the NOAA-P3 aircraft executed seventeen Lagrangian spiral descents advecting with the ambient wind, collecting in-situ microphysical data to characterize the vertical variability of hydrometeor shapes, sizes and phases in the stratiform regions behind mesoscale convective systems (MCSs). In order to quantitatively use the derived cloud properties to investigate microphysical processes occurring in stratiform regions, the timing and locations of the spirals must be understood in context of the meteorological evolution of each system.

Using level-II WSR-88D data and airborne dual and quad-Doppler measurements, the locations of the spiral descents were characterized with respect to the locations of the transition zone, the trailing stratiform region, the radar bright band, upper level front-to-rear flow, mid-level rear-to-front flow, and the rear inflow jet axis. Vertical and horizontal variations in number concentration, the derived slope parameter to analytic fits to observed size distributions and particle habits were observed among the various storms and in different locations within their trailing stratiform precipitation shields. In this paper, we use these measurements to diagnose preferred regions of sublimation, melting and evaporation, and synthesize a conceptual microphysical model of the trailing stratiform regions of summertime midlatitude MCSs.