Can Antarctic radar improve southern hemisphere weather forecasts?
Researchers show that continuous radar observations from Antarctica improve forecasts of atmospheric rivers and large-scale weather patterns
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Sparse weather observations over Antarctica limit the accuracy of Southern Hemisphere weather forecasts. Now, researchers show that assimilating hourly wind observations from the Antarctic PANSY radar improves weather forecasts and atmospheric river prediction, demonstrating the value of Antarctic radar data for numerical weather prediction.
view moreCredit: Assistant Professor Kazutoshi Sato from the National Institute of Polar Research, Japan.
Weather forecasts in the Southern Hemisphere (SH) are generally less accurate than those in the Northern Hemisphere because Antarctica and the surrounding Southern Ocean have relatively few weather observations. With limited information about atmospheric conditions in one of the world's most remote regions, forecasting models often struggle to accurately predict the movement of weather systems. This is especially true for atmospheric rivers that can trigger heavy rain, snowfall, flooding, and strong winds across Australia, New Zealand, South America, and Antarctica. Improving forecasts of these weather systems is therefore essential for protecting lives and property, supporting aviation and shipping, and helping communities prepare for hazardous weather.
To solve this problem, researchers from Japan investigated whether continuous radar observations from Antarctica could improve weather forecasts across SH. In a study made available online on July 11, 2026, in the Scientific Reports journal, Assistant Professor Kazutoshi Sato of the National Institute of Polar Research (NIPR), Japan, together with Professor Jun Inoue and Associate Professor Yoshihiro Tomikawa of NIPR; Dr. Akira Yamazaki of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Japan; and Professor Kaoru Sato from The University of Tokyo, Japan, found that incorporating hourly wind observations from an Antarctic radar into a numerical weather prediction system could improve forecasts of atmospheric circulation and atmospheric rivers over SH.
"Observations from the Antarctic radar are not currently incorporated into operational numerical weather prediction systems. Our findings show that assimilating these observations can improve forecast accuracy, demonstrating the value of continuous radar measurements for weather forecasting," says Asst. Prof. Sato.
The researchers used wind observations collected by the Program of the Antarctic Syowa Mesosphere–Stratosphere–Troposphere/Incoherent Scatter (MST/IS) Radar (PANSY) at Japan's Syowa Station in Antarctica. The PANSY radar continuously measures wind conditions in the atmosphere, providing observations at much higher temporal resolution than weather balloons or radiosondes, which are routinely used for weather forecasting but cannot be launched frequently in Antarctica because of financial and operational constraints. The team compared weather analyses and forecasts generated with and without assimilated PANSY radar observations during the 2022 austral winter. The weather analyses and forecasts were conducted using data assimilation and forecasting systems called “ALEDAS” , developed and managed by JAMSTEC on the Earth Simulator, JAMSTEC’s supercomputer. Both experiments included enhanced radiosonde observations from the Year of Polar Prediction in the Southern Hemisphere (YOPP-SH) campaign and covered seven atmospheric river events over the mid-latitude of SH, allowing the researchers to assess the added value of the Antarctic radar.
The results showed that assimilating Antarctic radar observations improved the representation of atmospheric conditions, including wind speed, temperature, and geopotential height, over Antarctica and the Southern Ocean in (re)analysis. Furthermore, the presence or absence of PANSY radar observations resulted in more than a 30% difference in atmospheric river moisture transport. These improvements persisted during the forecast period and enhanced predictions of atmospheric circulation and integrated water vapor associated with atmospheric rivers over SH mid-latitudes. Across all seven SH mid-latitude atmospheric river cases examined, forecasts that included the radar observations showed lower prediction errors than those based only on conventional observations.
"Although radiosonde observations are routinely performed to improve weather forecasts, high-frequency launches are challenging in extremely cold environments. We therefore proposed a new method for improving forecast accuracy using instruments capable of continuous, high-temporal-resolution observations," explains Prof. Inoue.
The study also highlights the broader importance of strengthening weather observations in data-sparse regions. Because uncertainties in Antarctic atmospheric conditions can spread far beyond the polar continent, improving observations there can enhance forecasts across much of SH. As weather prediction models continue to advance, integrating continuous observations from atmospheric radars and other emerging technologies could help make forecasts more reliable, benefiting disaster preparedness, transportation, scientific operations, and communities affected by extreme weather. Furthermore, reanalysis datasets with large uncertainties are widely used to estimate the Antarctic Ice Sheet surface mass balance under climate change. Assimilating PANSY radar observations may therefore improve our understanding of climate change.
About National Institute of Polar Research, Japan
Founded in 1973, the National Institute of Polar Research (NIPR) is an inter-university research institute that conducts comprehensive scientific research and observations in the polar regions. NIPR is one of the four institutes constituting the Research Organization of Information and Systems (ROIS) and engages in comprehensive research via observation stations in the Arctic and Antarctica. It strives to promote polar science by soliciting collaboration research projects publicly, as well as by providing samples, materials, and information. NIPR plays a special role as the only institute in Japan that comprehensively pursues observations and research efforts in both the Antarctic and Arctic regions.
Website: https://www.nipr.ac.jp/english/index.html
About Assistant Professor Kazutoshi Sato of the National Institute of Polar Research, Japan
Dr. Kazutoshi Sato is an Assistant Professor of Meteorology at the National Institute of Polar Research, Tachikawa, Japan, and is affiliated with The Graduate University for Advanced Studies (SOKENDAI). He holds a Ph.D. in Science and has more than a decade of research experience in polar meteorology and climate science. He has authored 53 peer-reviewed publications. His research focuses on polar meteorology, atmosphere–sea ice–ocean interactions, atmospheric rivers, numerical weather prediction, and the use of polar observations to improve weather models. His achievements include recognition in Nature Communications Editors' Highlights (2021).
About the Research Organization of Information and Systems (ROIS)
ROIS is a parent organization of four national institutes (National Institute of Polar Research, National Institute of Informatics, the Institute of Statistical Mathematics and National Institute of Genetics) and the Joint Support-Center for Data Science Research. It is ROIS's mission to promote integrated, cutting-edge research that goes beyond the barriers of these institutions, in addition to facilitating their research activities, as members of inter-university research institutes.
Journal
Scientific Reports
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
Impact of Antarctic radar on Southern Hemisphere atmospheric river reanalysis and forecast
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