Researchers in Japan demonstrate how vertically layered atmospheric rivers influence snowfall variability in Antarctica
Atmospheric rivers are responsible for transporting moisture and play an important role in snowfall over the ice sheet. However, conventional two-dimensional detection methods have been unsuccessful at capturing these systems accurately. Now, researchers have developed a new 3D algorithm for the detection of atmospheric rivers. Their findings reveal that atmospheric rivers form vertically structured moisture plumes that exert strong control over Antarctic precipitation and its long-term variability.
A rise in the global sea level is closely linked to snowfall in Antarctica, as it directly affects the mass balance of the Antarctic ice sheet. A major source of this snowfall is atmospheric rivers (ARs), which are long, narrow bands of concentrated water vapor in the atmosphere that transport huge amounts of moisture from tropical or subtropical regions toward cooler areas. When these systems reach Antarctica, they can trigger substantial snowfall events over the ice sheet. While this is known, detecting ARs over the Antarctic continent remains a major challenge due to the steep topography and extremely dry environment of Antarctica.
To address this issue, Kazu Takahashi, a doctoral student at the Graduate University for Advanced Studies (SOKENDAI), together with Professor Jun Inoue, Assistant Professor Kazutoshi Sato, Assistant Professor Naohiko Hirasawa, and Project Researcher Kyohei Yamada from the National Institute of Polar Research, developed a new three-dimensional (3D) AR detection algorithm. Their study, made available online on May 5, 2026, and published in Geophysical Research Letters on May 16, 2026, extends conventional 2D AR detection methods into a three-dimensional framework for accurately detecting ARs. “We found that ARs approaching Antarctica are not vertically aligned as previously assumed but are often tilted structures extending from the Southern Ocean into the upper atmosphere above the continent,” reports Mr. Takahashi.
Conventional 2D methods could not accurately represent this behavior, which led to unclear detection of Antarctic AR activity. The newly developed 3D method overcomes this limitation by identifying moisture transport across multiple atmospheric pressure levels simultaneously. To evaluate this new algorithm, the researchers analyzed precipitation observation data collected at Dome Fuji Station in East Antarctica during the 44th Japanese Antarctic Research Expedition (JARE44) and MODIS satellite data for the period from 2003 to 2004, corresponding to the JARE44 observation period. After this evaluation, the statistical analysis over Antarctica was conducted using ERA5 data from 1979 to 2023. The results showed that this new method was able to successfully detect ARs associated with more than half of the significant precipitation events observed during the expedition period.
“AR-related precipitation accounted for approximately 40% of the total precipitation at Dome Fuji,” Mr. Takahashi explains.
The atmospheric climatological analysis from 1979 to 2023 further revealed the dominant role of ARs in climatological Antarctic precipitation variability. Although ARs occurred less than 10% of the time across Antarctica, they accounted for approximately 30%-60% of the annual total precipitation, with contributions reaching up to 90% in some coastal and West Antarctic regions. Interestingly, the spatial pattern of long-term precipitation trends closely matched the distribution of AR-related precipitation trends, indicating that ARs strongly regulate long-term Antarctic snowfall variability.
Apart from the discovery, the study also has important meteorological implications. Although ocean-warming-induced ice loss is the primary driver of sea-level rise, variations in Antarctic snowfall alter ice-sheet mass balance and hence can influence the magnitude of sea-level rise. The findings also suggest that considering changes in AR activity is essential for improving projections of Antarctic climate variability and ice-sheet mass changes under global warming. The researchers further note that large-scale atmospheric phenomena, such as atmospheric warming, may influence Antarctic precipitation through changes in AR activity.
Explaining the motivation behind the study, the authors noted that earlier approaches were not able to sufficiently characterize ARs over Antarctica and that more advanced detection frameworks were needed to understand variability in Antarctic ice sheet. By incorporating the vertical dimension of moisture transport, the newly developed 3D detection method paves
the way for a powerful framework to support future expeditions into Antarctic precipitation processes and climate dynamics.
Reference
Title of original paper: Capturing Antarctic Precipitation With a 3D Atmospheric River Algorithm
Journal: Geophysical Research Letters
DOI:https://doi.org/10.1029/2025GL120986
About the Graduate University for Advanced Studies, Japan Established in 1988, the Graduate University for Advanced Studies, SOKENDAI, is one of the national universities of Japan. It operates as a distributed research university that cooperates
with research institutes throughout Japan and offers 20 doctoral programs with the support of parent institutes. The programs cover a broad range of academic fields, including particle physics, materials science, life sciences, astronomy, informatics, history, and culture. The
institute aims to contribute towards the creation and development of culture through education and research in academic theory and application. It boasts a highly international student community, with about 30% of its students coming from outside Japan. Since its
establishment, SOKENDAI has produced approximately 2,600 Ph.D. graduates in various academic fields of basic research. It is recognized for its strong research output, ranking 15th in Japan and 760th globally in U.S. News & World Report’s Best Global Universities.
About the National Institute of Polar Research, Japan
Founded in 1973, the National Institute of Polar Research (NIPR) is Japan’s leading center for comprehensive scientific research and observation in the Arctic and Antarctic regions. As one of the four institutes under the Research Organization of Information and Systems (ROIS), NIPR advances polar science through interdisciplinary research, long-term field observations, and the operation of research stations in both polar regions. The institute actively promotes international and collaborative research by publicly inviting joint research projects and providing researchers with access to polar samples, materials, and scientific data. NIPR also plays a unique role as Japan’s only institution dedicated to comprehensive observation and research efforts across both Antarctica and the Arctic, contributing to a deeper understanding of Earth’s climate, environment, and polar systems.
Website: https://www.nipr.ac.jp/english/index.html
About Researcher Kazu Takahashi from the Graduate University for Advanced Studies,Japan and the National Institute of Polar Research, Japan
Kazu Takahashi is a Ph.D. student and atmospheric scientist within the Department of Polar Science at SOKENDAI (the Graduate University for Advanced Studies), Japan. He is currently conducting research in the field of polar meteorology and climate science at the National Institute of Polar Research (NIPR). His research interests include atmospheric dynamics, precipitation processes, and climate variability in polar regions. To date, Mr. Takahashi has published two peer-reviewed papers as a corresponding author and co-authored a peer reviewed paper, contributing to broader insights into Earth’s climate system.
Funding information
This work was partly supported by JST SPRING (grant number: JPMJSP2104) and by the Japan Society for the Promotion of Science (JSPS) KAKENHI (grant numbers: 23H00523 and 24H02341). This study is part of the Science Program of the Japanese Antarctic Research Expedition (JARE) and was supported by the National Institute of Polar
Research (NIPR) under the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.
Media contact:
Kazu Takahashi
[email protected]
