I am interested in a wide variety of lightning physics questions. I consider myself primarly an "instrument guy" - someone
who develops instrumentation to better understand the underlying nature of how lightning works.
There is also a very real societal impact related to lightning research. To that end, I am also involved in investigations
how to better explore this important area of lightning research, particularly how lightning and lightning energetics
relate to severe weather.
One instrument we have developed is the Huntsville Alabama Marx Meter Array (HAMMA).
This is a set of sensors deployed in the Huntsville, AL area that measures the electromagnetic radiation produced by lightning in the
Very Low Frequency/Low Frequency (VLF/LF) regime. These sensors are quite adept at "seeing" the processes in lightning that produce
large scale changes in current, like the return stroke. In this sense, HAMMA is able to explore which parts of lightning are the most energetic.
In conjuction with the North Alabama Lightning Mapping Array, which is able to detect small scale discharges associated with lightning,
we are able to explore lightning in more detail than either system can alone.
One of the outstanding questions in lightning is "how does it all get started?". Currently, there are two theories for lightning
initiation: the hydrometor breakdown hypothesis and the runaway breakdown hypothesis. We are currently performing an investigation
that may shed some light (hah!) on which hypothesis may be favored and provide valuable data for modelers also interested in this
fascinating science question.
I also conduct research using the Lightning Imaging Sensor (LIS). LIS an optical sensor, in low earth orbit aboard the TRMM satellite,
that detects lightning from space. Currently, we are exploring better ways to utlize the data from LIS, particularly the energetics
each lightning flash. In addition, we are working on showing the utility of detecting lightning that may produce forest fires using LIS data.
We have added a high speed camera to our suite of instruments here at UAH. This will allow us to study the processes
in lightning that produce optical emissions in great detail. Here's an example of some of the things we're able to do:
In addition, I am part of the Geostationary Lightning Mapper (GLM) Science team. This instrument will
be flown on the GOES-R satellite and will provide continuous lightning observations from geostationary orbit. The team is currently exploring ways
to make best use of the GLM data once it goes online, using various current lightning data sets. One particularly important data set is LIS lightning
data. Much of GLM's design was based on LIS. A proper understanding of how to best use GLM data rests with properly understanding how LIS works.
I currently have a student researching the concept of "dark lightning". This idea is based on the possibility that some lightning processes,
particulaly the leader of intracloud lightning, may produce very little optical emissions. We are currently investigating how often this
may occur using HAMMA and LIS.