Microphysical, Kinematic and Lightning Properties of Deep Moist Convection across Northern Alabama during the Deep Convective Clouds and Chemistry Experiment

One of the primary goals of the Deep Convective Clouds and Chemistry (DC3) experiment is to study the kinematic, microphysical, and environmental control of lightning properties, particularly those that may govern the production of nitrogen oxides (NO_x), including flash type (intracloud [IC] versus cloud-to-ground [CG]), three-dimensional extent and frequency, in a wide variety of storm types. During DC3, several episodes of deep moist convection (DMC) were sampled with various ground-based meteorological platforms across northern Alabama. The Balloon-borne radiosonde sampling of both the pre- and near-storm environment aided in determining the state of the thermodynamic and kinematic (e.g. instability and vertical wind shear) environment that govern the intensity, longevity, and morphology of DMC and thus lightning production. The UAHuntsville Mobile Alabama X-Band Radar (MAX), UAHuntsville Advanced Radar for Meteorological and Operational Research (ARMOR) , and the National Weather Service's S-Band Weather Surveillance Radar (WSR-88D) at Hytop, AL (KHTX), comprise the multi-Doppler and dual-polarization radar network across northern AL that captured the kinematic and microphysical evolution of DMC. The NASA Marshall Space Flight Center North Alabama Lightning Mapping Array (NA LMA) along with data from Vaisala's National Lightning Detection Network (NLDN), documented the three dimensional properties of both IC and CG lightning. Meteorological, microphysical and chemical measurements made via aircraft available on two case days complement both surface and balloon borne instruments.

This unique network of polarimetric radars allow for multi-Doppler-wind synthesis and hydrometeor identification throughout the evolution of the DMC. With this analysis, theorized relationships between the kinematics of the updraft, in the mixed phase region (0 to -40 °C), the resultant riming growth of ice hydrometeors (e.g., graupel, - and hail volume mass) and the production of lightning can be explored. The updraft accumulation of graupel and small hail and the downdraft-driven descent of ice hydrometeors will be examined for their role in the production of IC and CG lightning, respectively. In addition to flash rate and type, the kinematic and microphysical control of flash extent will be studied as it is theorized to play an important role in the production of NO_x.

The primary focus of this study will be to present the co-evolution of lightning flash properties in the context of preliminary radar-based kinematic and microphysical retrievals for two high priority DC3 cases (21 May and 11 June 2012) during which aircraft measurements of NO_x were made in and around DMC over Northern Alabama. On 21 May, conditions favored both ordinary as well as linear convection across northeastern AL and adjacent sections of TN. During the aircraft mission of 11 June, multicellular convection occurred across much of southern TN and northern AL. Both of these cases offer the opportunity to compare and contrast the varying morphologies experienced during the field phase of DC3.