Pacific Phenomenon Could Cause More Thunderstorms in Hungary

In Hungary, experiments to detect very low-frequency natural radio noise generated by lightning have been carried out since the 1980s. Since 1993, a ball antenna has been used to detect Schumann resonances in the electric field. This measurement system remains operational at the Széchenyi István Geophysical Observatory near Nagycenk, possibly housing one of the world's longest datasets of this kind, according to Gabriella Sátori, Professor Emerita at the HUN-REN Institute of Earth Physics and Space Science (HUN-REN EPSS) and lead author of the paper. In their publication, the researchers used this dataset to study changes in the distribution of lightning activity.

 The study showed how changes in Schumann resonance (SR) frequencies on daily and annual timescales reflect shifts in global lightning activity. It also revealed that, in some cases, SR frequencies are sensitive to the movement of thunderstorm chains spanning hundreds of kilometres on distant continents, such as South America.

"I have been working in this field for almost ten years, and I am still amazed every day that measurements taken in Hungary allow us to study lightning activity in thunderstorms thousands of kilometres away," said Tamás Bozóki, the second author of the paper. "We already know a great deal about the Earth's lightning activity, but many questions remain unanswered, as lightning activity is constantly changing in relation to climate change. It is no coincidence that the World Meteorological Organization (WMO) recently classified lightning as an essential climate variable, providing crucial information about the ever-changing state of the atmosphere," he added.

"The most intriguing result of the paper is that a zonal phenomenon in the tropical Pacific, the El Niño Southern Oscillation (ENSO), influences lightning activity on a global scale," highlighted Gabriella Sátori. She noted that although it was demonstrated in the late 1990s that global thunderstorm activity also shifts north-south on the ENSO timescale, the meteorological background of this observation was not understood at the time. However, they have now managed to decipher it.

"During the warm phase of ENSO, heat accumulates in the tropics and then spreads over the following period, causing surface temperatures to rise slightly even at mid-latitudes, particularly in the Northern Hemisphere. Since lightning activity is sensitive to changes in surface temperature, this small increase in surface temperature resulted in a significant rise in lightning frequency in the cases studied," added the HUN-REN EPSS researcher.

As the next step, the researchers plan to examine lightning activity in Hungary over the past 30 years in greater detail to determine the potential impact of the Pacific phenomenon. The results will help us better prepare for thunderstorms that cause significant economic damage, such as supercells.