Charge structures in New Mexico, Colorado, and South Dakota.

摘要

Spend a summer in South Dakota, and one thing becomes undoubtedly clear: thunderstorms in the beginning of the season are different from storms at the end of the season. Large, organized Mescoscale Convective Systems (MCS's) reign in the spring and early summer, and small, isolated storm cells dot the landscape in the late summer. These late-summer storms are similar in morphology to New Mexico storms, which---with little exception---contain a main negative charge region, whereby the dominate charge delivered to ground by lightning is negative. This Normal Polarity (NP) charge structure is observable via the New Mexico Tech Lightning Mapping Array (LMA), which has been operated by Langmuir Laboratory since the late 1990s.;In contrast, South Dakota's MCS-type storms are similar in morphology to those from the 2012 Deep Convective Clouds and Chemistry (DC3) project, which revealed that thunderstorm charge structures in north-central Colorado were predominantly anomalous---i.e. not NP---characterized by positive cloud- to-ground (+CG) lightning, and lower than-normal CG rates.;In this study, we manually identify charge regions in LMA data for the above three geographic regions---New Mexico, Colorado, and South Dakota---and we use this data set to demonstrate our ability to connect charge structure with storm morphology, and to relate these findings to charging mechanism theories. Ultimately, we want to create a "charge structure climatology" by automating charge identification, which will provide a platform for validating storm charging mechanism theories.