Using GIS to Display and Analyze Houston Lightning Mapping Array Data During Hurricane Harvey

The Houston Lightning Mapping Array (HLMA) network has been in use since April 2012 and continues to be a key instrument in plotting the 3-D behavior of lightning in the Houston area. The HLMA makes regular observations of the time, latitude, longitude, height, and power of each lightning point during a thunderstorm event that passes within the range of detection of the network. The lightning data are output to a public website (https://atmo.tamu.edu/ciams/lma/index.html) every minute. The data are displayed in the form of a 2-D plot, which is adequate for general viewing and public use.

Geographic Information Systems (GIS) are a set of tools used for analysis, visualization, and management of geospatial and aspatial data. Using GIS software not only gives us the ability to make a better view of the data, but also allows for the relationships between the locations of the measurements to be plotted out and sorted with respect to any category we can think of regarding the HLMA’s database. We can quantify the data with respect to lightning event number, distance to closest strike, time of event, magnitude, etc. We can also perform spatial analyses on the data to find new trends that we never thought existed before.

Utilizing this type of analysis in an innovative fashion can lead to a more qualitative lightning research and advanced warning system for first responders and the public. For example, through the use of GIS, trends that link the frequency of occurrence and the time of lightning events based on the spatially related variables in the database can be investigated. Thus, a tandem between the HLMA data feed and an innovative GIS script can lead to a better way of determining not only the storm location but also whether the convection is increasing or decreasing.

In this study, Hurricane Harvey is used as a real-world example of merging GIS methods and techniques with real-time lightning data. Hurricane Harvey was one such event that devastated the Gulf Coast of South Texas and provided numerous lightning data points that were recorded by the HLMA. The lightning data points are plotted with respect to lightning event density, distance to closest strike, time of event, and magnitude just before the major flooding event occurred. Preliminary GIS analysis shows a strong correlation between areas of major flooding and greater frequency of lightning events. The data are further spatially analyzed for trends as well as displayed in a more qualitative manner on the website for public use. Furthermore, GIS analysis of HLMA data can lead to a better warning system for first responders.