A Sprite, A Megaflash, and a Gigantic Jet Walk Into A Bar in Lemont

Dr. Tim Logan, Texas A&M University
EVS Seminar Graphic

The Texas Gulf Coast is impacted by electrified deep convection which can occur in any given calendar month. The Houston Lightning Mapping Array (HLMA), located in Texas and operational since 2012, provides three-dimensional lightning data in real time and currently consists of a network of 10 sensors which surround the inner Houston Metropolitan area. The HLMA detects and maps very high frequency (VHF) electromagnetic sources from electrified deep convective clouds with an efficiency of virtually 100% within 100 km of the centroid. Though the efficiency rapidly decreases with distance (e.g., inverse square law), there is adequate coverage of lightning activity over the Gulf of Mexico (e.g., tropical convection) and much of Texas (e.g., continental deep convection). The HLMA is unique in that it serves a major metropolitan area situated within a transitional marine/continental region. Recently, the HLMA network has observed curious lightning phenomena such as transient luminous events (TLEs) and megaflashes. Examples of TLEs include sprites, jets, and gigantic jets. During the past two decades, due to better camera technology and advanced lightning detection techniques, more TLE types have been discovered such as ELVEs, HALOs, Ghosts, and Pixies. Fortuitously, more information is being gathered on the origins and nature of TLEs each year thanks in part to a growing interest from the “citizen science” community. However, there is still much to be examined and studied about not only how they form but their impacts on the global charge structure. This seminar documents several events that were observed within the confines of the HLMA and includes: the 16 May 2024 flooding and wind event over Southeast Texas (Houston and Bryan/College Station), a sprite/HALO derived from a parent flash which was negative and exhibited an unusually strong peak current (-401 kA), a near 200 km megaflash observed during Hurricane Nicholas (2021), a series of gigantic jets from the same tropical cyclone within a few hours of landfall, and more sprites from Dr. Logan’s research group. Special attention is paid to the comparison/contrast of the nature of these events with previous work, charge analyses, inferred cloud microphysics, and convective environment.

Logan Biosketch

•              Dr. Tim Logan is an Assistant Professor at Texas A&M University. His primary research goals are (1) investigate the relationship between lightning source/flash rates and precipitation/flooding events in the Houston Metropolitan Area and communities along the Texas Gulf Coast, (2) analyze the long-term aerosol impacts on low-level and deep convective cloud development, and (3) discern the possible impacts of biomass burning smoke on cloud top lightning discharges and upper atmosphere lightning. He teaches courses in Weather and Climate for non-science majors, Air Pollution Meteorology, and graduate level Atmospheric Physics and Radiation. He is the director of the Houston Lightning Mapping Array and is a co-discoverer of the WMO-certified world’s longest lightning flash (768 km).

 •              Tim’s current research consists of the following funded projects:

(1) Aerosol impacts on lightning and severe weather in the Houston Metropolitan Area and Texas Gulf Coast.

(2) Aerosol transport and impacts on marine and continental boundary layer cloud development with an emphasis on investigating the direct and indirect effects of biomass burning aerosols derived from wildfires and natural processes.

(3) Using total lightning to investigate aerosol radiative and microphysical impacts on deep convective clouds.

(4) Using total lightning to investigate relationship between lightning and severe flooding using the Houston Lightning Mapping Array (HLMA) in coordination with personnel from the Texas Division of Emergency Management Office and related emergency first responders.

(5) Analyzing deep convection that produces transient luminous events (TLEs) in Texas.

•              Tim is an avid storm chaser and brings along his lightning sensors and cameras at every opportunity. Tim is an avid hockey fan who plays as a goalie and defenseman in a pond hockey league