Unprecedented rainfall reported on King George Island during the southern winter – 2024-07-16 09:32:11 – 2024-07-16 09:34:19

In an unprecedented event, national researchers have documented in a recent scientific article a rain event on the White Continent during the southern winter on King George Island. This phenomenon occurred during the first days of July 2023, when the Frei base reported not only temperatures above zero but also liquid precipitation instead of snow.

“Not only was the fact that it rained extraordinary, but also the duration of the event. King George Island endured a 12-hour downpour,” said climatologist Raúl Cordero, a researcher at the University of Santiago de Chile (Usach) and member of the National Antarctic Science Program (Procien).

The cause of this event was an atmospheric river, understood as a warm band that transports a large amount of heat and humidity that, upon reaching land, condenses and forms clouds that discharge abundant precipitation.

“The article highlights the importance of atmospheric rivers in the Antarctic Peninsula during winter, a phenomenon that has been little studied until now. It reveals how these events can cause significant increases in temperature and rainfall in a region that is typically cold and snowy,” added Deniz Bozkurt, researcher at the Department of Meteorology at the University of Valparaíso and lead author of the text.

Atmospheric rivers produce significant increases in temperature, rising freezing levels, and liquid precipitation instead of snow in coastal areas. This can also accelerate ice melting and affect the stability of ice sheets and glaciers. However, atmospheric rivers can also have positive impacts, such as increasing snow accumulation in the interior parts of the continent, which is beneficial for the stability of Antarctic ice.

These events have been observed previously during the austral summer, but not during winter. The studies involved in situ observations of atmospheric parameters through the launch of radiosondes and allowed a better understanding of these phenomena and their impacts.

The importance of Antarctic science in winter

In this context, the work carried out by master’s students Álvaro Gómez and Benjamín Carrillo, members of the Usach Antarctic Research Group led by Cordero, was essential. They remained from March to October 2023 at the “Professor Julio Escudero” base of the Chilean Antarctic Institute (INACH), on King George Island, to keep the TARP-02 (Transportable Antarctic Research Platform) research platform operational. These students launched the radiosondes that allowed detailed monitoring of the atmospheric river.

“The only way to monitor the effects of these types of phenomena is with on-site observations. This winter rain event would not have been detected or would have gone unnoticed if two researchers from my group had not been working there,” says Cordero.

It is essential to study these phenomena in winter, says Bozkurt, because they have a significant impact on the region, as recent observations show.

“Collecting data in winter helps to better understand climate patterns and their seasonal variations. In addition, the data collected can help identify beneficial effects, such as increased snow cover, and dangerous effects of these events. These data sets are valuable for evaluating and validating models, which tend to have significant errors in and around Antarctica,” said the researcher from the University of Valparaíso.

Atmospheric rivers are arriving more frequently to Antarctica. This would clearly explain “why we have had increasingly frequent temperature records on the White Continent,” says Cordero. This underlines the need for constant monitoring throughout the year and not just in the summer season.

These phenomena are natural, but climate change and global warming are considered key factors potentially contributing to the increased frequency and severity of these events, although several issues remain to be clarified.

“Changes in climate facilitate the formation of atmospheric rivers and increase temperatures in the region. Further modelling efforts and statistical analysis are needed to clarify this,” Bozkurt concludes.

Climate connections

Atmospheric rivers are not only a phenomenon of Antarctica, but also affect our country. These events can generate intense rainfall, potential flooding and landslides, especially in the central and southern areas. Depending on their intensity and duration, they can be both beneficial and dangerous, as they can also increase snow cover, benefiting water resources.

The article “Atmospheric river brings heat and rain to the north of the Antarctic Peninsula during the southern winter of 2023” was published in the journal Geophysical Research Letters and included the participation of researchers Deniz Bozkurt, Jorge Carrasco (University of Magallanes), Raúl Cordero, Francisco Fernandoy (Andrés Bello University), Álvaro Gómez-Contreras (University of Chile), Benjamín Carrillo (University of Magallanes) and Bin Guan (University of California).

INACH is a technical body of the Ministry of Foreign Affairs with full autonomy in all matters related to Antarctic matters of a scientific, technological and dissemination nature. INACH complies with the National Antarctic Policy by encouraging the development of research excellence, effectively participating in the Antarctic Treaty System and related forums, strengthening Magallanes as a gateway to the White Continent and carrying out actions to disseminate Antarctic knowledge to the public.