January's Hunga Tonga Eruption Causes Significant Cooling Event in the Stratosphere, Might Affect This Winter and the Next

In January, the Hunga Tonga eruption led to a significant cooling event that is currently being tracked in the stratosphere. How this may impact both the current and following winters is discussed by an expert.

Over the southern hemisphere, strong cold anomalies continue to be tracked in the stratosphere. The significant stratospheric water vapor cloud produced by January's Hunga Tonga eruption is what is responsible for the anomalous cooling. Record-low temperatures have been found in the southern stratosphere, cooling on this scale had not previously been observed in satellite records.

How this cooling event developed and how it might affect the weather in the upcoming winters of 2022 and 2023 are explained by a severe weather expert from Severe Weather Europe.

Stratosphere

The troposphere, which is the lowest level of the atmosphere, is where all clouds can be found. Over the polar regions, it can reach an altitude of about 8 km, and over the tropics, it can reach an altitude of about 14 km to 6 km.

The stratosphere is a much deeper layer that lies above it. This layer is very dry and about 30 km thick.

While the planet's weather is in the lowest layer of the atmosphere, these layers are crucial because impacts from above can significantly alter it. The stratosphere in particular is well known for its impacts and modifications on the jet stream and the Polar Vortex.

Volcanic Eruptions and the Atmosphere

Different gases and materials can be directly ejected into the stratosphere by powerful volcanic eruptions. This can have a variety of global and regional atmospheric effects depending on the type and quantity of particles.

On January 15, 2022, a submarine volcano called Hunga Tonga in the South Pacific erupted violently. Massive volcanic activity from Tonga caused a plume that briefly touched the mesosphere at 58 km.

The eruption released a large amount of water vapor as well as volcanic gases, including sulfur, into the stratosphere. Due to the volcano being "submarine," or below the water's surface, and erupting out of the ocean, the volume of water in the plume was very high.

This eruption was powerful enough to cause shockwaves that were felt by monitoring stations all over the world.

Later analysis determined the eruption column's maximum altitude to be approximately 57.5 kilometers. The massive volcanic cloud continued to circle the entire hemisphere after reaching its peak in the mesosphere, remaining in the middle to the upper stratosphere.

This cloud contained a variety of particles, including water vapor.

Cooling Effect

Water vapor also cools, but not at the surface as sulfur does. Instead, it causes the stratosphere to cool. Regarding the Hunga Tonga eruption, the total water content increased from 1500 Teragrams, which is normal, to more than 1700 Teragrams, which is a 10% increase. A sizable "cloud" of water vapor that circles the globe in the stratosphere has a significant cooling effect and is likely to affect future global weather patterns.

In the southern hemisphere, cooling had already been noticed since May. By October, most of the southern hemisphere experiences colder temperatures. This overall significant anomaly in the southern stratosphere indicates that the Polar Vortex is currently stronger. Record-low temperatures are being observed and are expected in the mid-stratosphere for this time of year.

Cooling Anomalies

The most recent analysis reveals that the cooling anomalies extend into the polar regions. The majority of the southern stratosphere is consequently colder than usual. After such a powerful injection of water vapor into the stratosphere, this outcome was somewhat predictable.

According to data analysis, from the lower stratosphere up to the middle and upper stratosphere, the southern stratosphere is generally colder than usual. The mid-to low-stratosphere is covered by the marked region, and the cold anomalies there are primarily caused by water vapor cooling.

The water vapor cloud cooling will cause the mid-latitudes to stay colder as the south polar stratosphere regions warm.

Previous Studies

In March, a study, led by Meng Zhou, was published in the journal Advances in Atmospheric Sciences, which stated that the Hunga Tonga eruption won't be powerful enough to overcome the longer-term trend of global warming.

In contrast, an article by NASA published in August pointed out that Since water vapor traps heat, even though the Tonga volcano did not release significant amounts of aerosols, the enormous amounts of water vapor produced by the eruption may have had a small and temporary warming effect. The effect wouldn't last long enough to notably exacerbate the effects of climate change because the extra water vapor would dissipate once it left the stratosphere.

Influence on Winter

The South Pacific island of Hunga Tonga's eruption in January released a significant amount of water vapor, which was injected into the stratosphere. As we move into the end of the summer and the beginning of the winter, that water vapor is still significantly cooling the southern stratosphere.

According to historical data, During later warming events in the stratosphere over those in the northern hemisphere, there is a flimsy indication of stratospheric cooling in the south. However, since other background signals might be in play, much more research is required.

If the stratosphere warms during the winter in the northern hemisphere, circulation may be severely disrupted. This results in pressure changes and may let loose arctic air into Europe and the United States.

It would make sense for the southern hemisphere's stratospheric changes to affect the northern hemisphere as well. The upcoming winter will be a fantastic "lab test" in real life demonstrating the potential global weather changes because of the significant cooling in the southern hemisphere. This analysis was done by Andrej Flis, an expert in various fields of weather, and a contributor for Severe Weather Europe.