Photo/Illutration Bitchu Matsuyama Castle is enveloped in a sea of clouds. (Provided by the city government of Takahashi, Okayama Prefecture)

TAKAHASHI, Okayama Prefecture--A university lab is providing artificial intelligence-based probabilities on whether a sea of clouds will form around the “mountain castle in the sky” here.

Lab members at the Okayama University of Science started the daily cloud forecasts in October for the area around Bitchu Matsuyama Castle.

Their numbers could help tourists plan trips when clouds are more likely to form and surround the castle, enhancing the picturesque beauty of the historic site.

Bitchu Matsuyama Castle is located along the Takahashigawa river near the 487-meter peak of Mount Gagyuzan.

A sea of clouds may cover the area on mornings from late September through early April, but the peak season is from October through December.

The clouds are prone to form when a number of conditions are met, including: calm wind in the altitude range of 1,000 to 2,000 meters; a large temperature difference between daytime and night on the previous day; and clear weather on the previous night.

But the formations are not guaranteed, and many early morning visitors who throng a mountain observation deck 1.1 kilometers from the castle can leave disappointed.

Officials of the city government’s tourism division said they often receive inquiries about when a sea of clouds will form.

However, they can only give explanations on weather conditions that might facilitate the cloud phenomenon.

Members of the lab, led by Yukitaka Ohashi, a professor of meteorology with the OUS Faculty of Biosphere-Geosphere Science, installed a camera at the observation deck to take automated pictures of the area surrounding the castle.

They collected images from October last year through May and fed the information into an AI system, along with temperature, humidity and wind speed data from the same period.

The lab also developed a computer program that enabled the system to give the probability of a sea of clouds forming at the castle on the following morning.

The forecasts are accessible, with links from the websites of the Takahashi city government and OUS, at (http://unkai.cloudfree.jp/unkai-t.html).

The Japanese website offers the probabilities that on the following day: (1) a castle in a sea of clouds will be visible from the observation deck; (2) a sea of clouds will form but will not surround the castle; and (3) there will be no sea of clouds.

The probabilities are renewed three times a day at 4:20 p.m., 8:20 p.m. and 10:20 p.m.

Lab members resumed photographing the area around the castle on Sept. 25 to improve the forecast accuracy. They are storing pictures taken at 5-minute intervals between 4 a.m. and 11 p.m.

Ohashi previously used an AI system to forecast the occurrence of a sea of clouds in the Miyoshi Basin of Hiroshima Prefecture. The system achieved an accuracy rate of about 80 percent, so he applied the technology for Takahashi’s castle in the sky.

“Visitors feel uneasy about coming to the site without any available information,” Ohashi said, adding that the accuracy rate is not high enough yet. “I hope to feed more data into our AI system to help provide information for viewers of the mountain castle.”

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