In a national first, US scientists have used high-resolution lidar data to determine lightning’s impact on tropospheric ozone.
Scientists at the University of Alabama in Huntsville (UAH) have used the university’s Rocket-city Ozone Quality Evaluation in the Troposphere (RO3 QET) lidar to measure ozone that was chemically produced by summertime lightning over the USA. Following further development, the research could play an important role in air quality prediction and assessment.
The UAH team estimated lightning nitric oxide emissions based on the observations of Vaisala’s US National Lightning Detection Network (NLDN). They then measured the resulting ozone created by the lightning downwind of the storms, where clear conditions allowed lidar to function, and quantified the ozone enhancements due to lightning.
In the winter, intermixing of stratospheric ozone with the troposphere in a process called stratospheric tropospheric exchange (STE) is the chief means of ozone transport into our air, but in summertime that process subsides and lightning bolts create significant ozone enhancements in the middle to upper troposphere, particularly in the south-eastern USA.
“When lightning introduces ozone into the upper troposphere, there is some downward transport mechanism that will affect lower tropospheric ozone,” explained Dr Lucy Wang, a UAH Earth Systems Science Center (ESSC) research associate and lead author of a paper on the team’s findings.
“In the troposphere, ozone is considered a bad gas,” she said. “It can worsen bronchitis, emphysema and asthma. We are investigating the processes that influence the ozone production. There are still many uncertainties in this research that we are trying to improve upon.”
The team used data from a lidar facility on the top floor of the National Space Science Technology Center (NSSTC) in Cramer Research Hall in Huntsville, Alabama, one of just five such atmospheric lidar facilities in the USA and about 15 worldwide. - February 2017