Analysis of the 6 July 2015 PECAN MCS Utilizing Airborne- and Ground-Based Doppler Observations and Airborne In-Situ Microphysical Data

On 6 July 2015, a mesoscale convective system (MCS) over South Dakota was observed as a part of the Plains Elevated Convection at Night (PECAN) experiment. Ground-based observations were gathered by a suite of mobile Doppler radars, mesonets, and sounding arrays. Additionally, the NOAA P-3 aircraft performed 10 pseudo-dual-Doppler legs (PDDs) and 8 spiral ascents/descents within the transition zone (TZ) and enhanced stratiform rain region (ESR) of the MCS. Several of these spirals were conducted behind two developing bow echoes, with at least one spiral within the rear inflow jet. The NOAA P-3 was outfitted with the X-band (3.2 cm wavelength) NOAA Tail Doppler Radar (TDR). The TDR has a range of ~70 km, and an extended Nyquist velocity of ± 51 m s^-1. The TDR alternates scanning fore and aft of the aircraft, providing for pseudo-Dual-Doppler retrievals. Additionally, Optical Array Probes (OAPs) were mounted on the NOAA P-3 and their data used to compute particle number, sizes, and shapes.

A subset of the data collected from the TDR during the 10 PDDs conducted on 6 July has been synthesized with data from several ground-based radars using the Spline Analysis at Mesoscale Utilizing Radar and Airborne Instrumentation (SAMURAI) technique. These SAMURAI analyses provide a detailed estimate of the kinematic and radar reflectivity structure during several periods of system evolution. Of the 8 spiral ascents/descents conducted on 6 July, 4 spiral ascents/descents were performed within the TZ, with an additional 4 spirals in the ESR. Data collected by the OAPs during these spirals were processed by the University of Illinois OAP Processing Software (UIOPS), allowing for the generation of vertical profiles of particle mass and number distributions, total water content, total number concentration, and median mass diameter. When considered in the context of the SAMURAI analyses, these profiles and accompanying profiles of relative humidity and temperature help explain how the microphysical processes occurring in various regions of the MCS influenced the system dynamics. The relationship between diabatic cooling and the flows within this nocturnal elevated MCS will be discussed.