Planetary waves are fluctuations in temperature, pressure, density and wind velocity that cover the entire thickness of the atmosphere. This phenomenon, which resembles ocean tides in many ways, is not visible to the human eye and can last from one to thirty days. Planetary waves are formed in the lower layers of the atmosphere and propagate to its uppermost layers, where their amplitude increases due to lower atmospheric density. In the upper layers, waves are the dominant form of motion, as they determine the transfer of energy and momentum between different layers of the atmosphere. Finally, these waves are also the driving force of the atmospheric meridional circulation (the transfer of air masses between the Earth’s equator and the poles), which takes place on a global scale and most strongly affects the composition of the atmosphere.
Changes in meridional circulation affect the behaviour of the ozone layer, which, as many scientists believe, acts as a kind of guardian of life on Earth, protecting it from the harmful effects of the hard part of the ultraviolet radiation of the Sun. In this connection, scientists from SPbU decided to analyse the impact made on global atmospheric circulation by planetary waves that last for 16 days and intensify in winter in the northern hemisphere. In the past, such waves were studied using satellite data, but no one has yet estimated the contribution of the 16-day wave to changes in temperature and wind velocity on the planet.
“A study of this kind requires a series of numerical experiments and a simulation of atmospheric circulation. We conducted such experiments and showed that the impact of just one 16-day wave on average per month can cause the velocity of atmospheric currents (winds) to change by up to 5%. It would seem that the percentage is quite small, but we are talking about a global, constantly active process that has a significant impact on climatic conditions, including temperature,” Andrey Koval, doctor of physical and mathematical sciences, is quoted as saying by SPbU.
The authors of the study estimate that, under certain conditions, the combined contribution of several planetary waves can produce such powerful wind and temperature disturbances that their echoes propagate down to the surface. This results in periods of extreme warming and cooling in the Arctic and in northern temperate latitudes.