Current models do not measure gravity waves with sufficient accuracy, new research suggests. This is important, the study authors say, because it affects the accuracy of atmospheric modeling technologies, which are essential tools in our arsenal when it comes to predicting weather events and creating climate simulations. That means fixing these deficiencies could improve their reliability and increase the accuracy of future studies.

So, what exactly is a gravity wave? As the National Weather Service explains, air can move in one of two ways – straight or in a wave. The waves themselves can either be vertical or horizontal. A gravity wave (not to be mistaken for a gravitational wave) is simply a vertical wave. To visualize a gravity wave, picture the ripples created when a pebble is thrown into a lake. 

Gravity waves form when fluids with different densities meet. An example of this would be waves in the sea. These waves can also form in the atmosphere, where density differences caused by differences in temperature create a similar movement – leading to the turbulence you might experience during a flight.  

In this piece of research, scientists compared data collected from ERA5– atmospheric modeling technology commonly used in climate research – with direct observations made at the Syowa Station in Antarctica using a super-pressure balloon and a large-scale atmospheric radar called PANSY. 

Both detected gravity waves with near-inertial frequencies, aka waves with speeds similar to the natural rotation speed of the Earth. However, the results suggest that ERA5 underestimated the amplitude of these waves. The researchers suggest this is because it is unable to simulate waves with wavelengths less than 3 kilometers or track their exact position with sufficient accuracy.  

“Our study shows that even high-resolution general circulation models used for the latest reanalysis cannot fully reproduce gravity waves and their effects,” lead author Yoshihiro Tomikawa, an associate professor at ROIS, said in a statement – a limitation that could lead to inaccuracies when predicting weather and climatic events. As well as emphasizing the limits of existing models, the study’s authors argue the study highlights the importance of including direct observations in research.

While the scientists in this particular study were measuring waves on the smaller end of the spectrum, they can appear in all sizes – earlier this year, for example, Hurricane Helen cooked up a giant gravity wave over the Gulf of Florida. 

The study was published in the Journal of the Meteorological Society of Japan.