Mt. Fuji summit remains vital research spot 20 years after weather station became unmanned

In late July, as climbers celebrated their successful ascents to the summit of Mount Fuji, researchers wearing helmets and safety harnesses were climbing onto the roof of a nearby research facility on Japan’s highest peak.

The Japan Meteorological Agency (JMA)’s former Mount Fuji Weather Station, now known as Fuji Research Station, is located on the mountain’s Kengamine peak at an altitude of 3,776 meters, and this October will mark 20 years since manned operations ended there. Formerly housing a weather radar, the station was once known as a “typhoon fortress.” It is now being utilized as a base for high-altitude observations.

Shungo Kato, 53, an associate professor at Tokyo Metropolitan University who was installing an air intake device outside the building, commented, “Mount Fuji has a lone peak at a high altitude. It’s an extremely valuable location for directly studying the upper atmosphere (the free troposphere), unaffected by the ground.” At the summit, researchers monitor atmospheric pollutants such as carbon monoxide and the volcanic gas sulfur dioxide. They say the station can pick up the effects of volcanic eruptions in places as far away as Sakurajima in southwestern Japan’s Kagoshima Prefecture.

Year-round manned observations began at the summit in 1932. In the winter, the temperature has dropped to minus 30 degrees Celsius and lower, and the station holds the record for the highest wind speed ever recorded in Japan, at 91 meters per second. It is the most severe natural environment in the country. Although the weather radar proved effective in typhoon monitoring, it ceased operations in 1999, and manned operations by JMA workers ended in 2004. It currently functions as an Automated Meteorological Data Acquisition System (AMeDAS) observation point.

Researchers in fields like atmospheric chemistry began to focus on this environment. Yukiko Dokiya, 85, a professor emeritus at Edogawa University in Chiba Prefecture, and others played a pivotal role in founding the nonprofit organization Mount Fuji Research Station. The group began renting part of the building from the JMA, and since 2007, researchers covering various fields from atmospheric chemistry and lightning to cosmic rays, permafrost, and high-altitude medicine have jointly been using the facility, primarily during the summer.

According to Kato, there has recently been a decline in atmospheric pollutants from China and other locations, but it is now known that this actually reduces the amount of sunlight-blocking substances, thus accelerating global warming. “Continuously monitoring changes in atmospheric trace constituents at high-altitude sites like Mount Fuji is crucial for understanding global environmental changes,” Kato said. Results of the observation from the facility include the first-ever discovery of microplastics in clouds by a research group led by Waseda University professor Hiroshi Okochi.

Meanwhile, a surge in the number of climbers on Mount Fuji and reckless ascents have emerged as problems and in July there were a series of deaths in bad weather. Amid these circumstances, Tokyo-based Aoyama Civil Engineering Co. specializing in ground and environmental surveys this year fully launched the website “Imafuji,” which provides weather data and live camera images from 11 locations on Mount Fuji, including the observation station and hiking trails. Yui Oyaizu, 43, a weather forecaster handling the project, commented, “The weather conditions at each hiking trailhead are different and there are times when the wind is unbelievably strong. We encourage climbers to be prepared both in terms of equipment and mentally.”

Dokiya noted, “The number of researchers who will have used the observation station is expected to reach a total of 7,000 by the end of this fiscal year. I never dreamed we would be able to continue for so long.

“Mount Fuji is appealing as a place for young researchers to gather. Though maintaining the activities is challenging financially and in other areas, we hope to keep using the station.”

(Japanese original by Koichiro Tezuka, Photo Group)