Particles raining down from space offer three-dimensional views inside swirling tropical storms.
Muons created from cosmic rays hitting Earth’s upper atmosphere have revealed the inner workings of cyclones on Japan, researchers report Oct. 6 in scientific reports. The new imaging approach could lead to a better understanding of storms, the researchers say, and offer another tool to help meteorologists forecast the weather.
“Cosmic rays are sustainable natural resources that can be used anywhere on this planet for 24 hours. [a day]”, says geophysicist Hiroyuki Tanaka of the University of Tokyo, so it’s just a matter of harnessing them.
Muons offer a glimpse into storms because variations in air pressure and density change the number of particles that pass through a storm. By counting how many muons reached a detector on the ground in Kagoshima, Japan, as cyclones passed by, Tanaka and his colleagues produced rough three-dimensional maps of the density of air within storms. The approach gave the team an inside look at low-pressure regions in central rotating storm systems.
Muons, which are similar to electrons but about 200 times more massive, can scatter molecules in the air. They are also unstable, meaning that they decay into electrons and other particles called neutrinos given enough time. As air pressure increases, so does its density. That, in turn, increases the chances that a cosmic ray-born muon will stray from its path to a detector or slow down enough to decay before passing through the atmosphere.
For every 1 percent increase in air pressure, Tanaka and colleagues say, the number of muons that survive the passage from the upper atmosphere to the ground decreases by about 2 percent.
Tanaka has previously used cosmic ray muons to look inside the volcanoesand suspects that others have used the particles to study the weather (Serial number: 04/22/22). But, she says, this appears to be the first time anyone has made 3-D muon scans of the interior of a storm.
“It’s an interesting approach,” says meteorologist Frank Marks of the National Oceanic and Atmospheric Administration’s Atlantic Oceanographic and Meteorological Laboratory in Miami, who was not involved in the research.
He doesn’t expect muon imaging to replace conventional weather measurements, but it is another tool scientists could use. “[It] It would be complementary to our existing techniques for providing three-dimensional maps of storms with our other traditional observing systems, such as satellites and radar.”