Cherry blossom season is big business in Japan. Photo / Getty Images
Cherry blossom season is big business in Japan. Photo / Getty Images
As cherry blossoms – or Sakura – are beginning to bloom earlier in Japan, AI technology is being used to give a more accurate forecast for the start of spring.
The start of the cherry blossom season brings a boost for tourism and local businesses, with many visitors planning trips around the blooms.
During this time, shops and restaurants are packed with sakura themed merchandise, food and drinks.
Locals traditionally celebrate the season with hanami – which are viewing parties and picnics among the trees in cherry blossom hotspots.
In Tokyo, the pink sakura flowers have already started to appear – just over a week earlier than their expected arrival on March 23.
This year, Japanese weather firm Weathernews has started crowdsourcing data for the blossoms, using photos of buds sent in to its website and app by 10,000 citizens.
"Cherry blossom forecasting is impossible for us without this system," spokeswoman Miku Toma told the Daily Mail.
Weathernews launched its "Sakura Project" in 2004, asking members to choose their own cherry tree and send regular photos of its buds to the firm.
"We realised we could see the details of how buds grow thanks to the pictures sent to us," said Toma. "So we decided to incorporate the project to help predict blossoms."
Observing changes in the buds can give an accurate forecast of how far away from blooming the tree is.
A month before blossoming, the sakura bud is small and firm, before the tip changes to a yellow-green colour ten days later. After that, a darker green part becomes visible. Once the bud turns a faint pink colour, blossoms are a week away.
Over the last 15 years, the firm has gathered data from more than two million reports – which have increased the accuracy of its forecasting.
Another forecaster, Otenki Japan, is run by a subsidiary of precision-equipment manufacturer Shimadzu – it started using artificial intelligence to predict cherry blossoms in 2018.
According to Japan News, the company even started a unique competition to see who would be more accurate in their predictions – humans, or AI.
As of March 1, both human and AI prognosticators were calling for the flowers to appear earlier than in an average year nationwide. But in some locations, the expectations differ by a few days. The results of the competition will be announced on April 5 on the company's Otenki Japan weather forecast website.
To apologize for my absence, enjoy these cherry blossoms I passed in Tokyo today! pic.twitter.com/HUov3AhDH9
In the company, human weather forecasters had predicted the blooming dates until 2017, but in 2018 AI replaced them for the first time. However, its 2018 predictions came within two days of the actual blooming dates for only 31 per cent of 45 locations in the country.
The hit rate of the AI predictions is lower than that of predictions by Hisashi Kataoka.
Kataoka, 41, is the company's group leader and has worked as a weather forecaster for 17 years. His average hit rate was 37 percent from 2010 to 2017.
So, the company gave its AI additional information about cherry blossoms' cycle of being dormant in autumn and winter and developing flower buds in early spring, and about changing weather patterns, such as temperature data. As a result, the rate improved to 60 per cent in a simulation based on last year's blossoming dates.
Kataoka said: "I held a 63 percent hit record in the past. I'm looking forward to the results."
Japan's Meteorological Agency stopped its sakura forecast, which ran for more than fifty years, in 2010. It said other organisations were now making forecasts with sufficient accuracy.
Locals traditionally celebrate the season with hanami -viewing parties and picnics among the trees in cherry blossom hotspots. Photo / Getty Images
However, the agency still declares the official start of cherry blossom system, by monitoring 58 "barometer trees" around the country – the locations of which are a closely guarded secret. But one of these trees is known to be in Tokyo, at the Yasukuni shrine.
Every March, inspectors visit these trees once a day – increasing to twice daily as they begin to blossom. Once five or six blossoms begin to appear, the cherry blossom season is announced.
"People pay more attention to the cherry blossom season than any other flower in Japan," Ryo Dojo, an official of the statistics unit at the Japan Meteorological Agency, told AFP.
When it comes to predicting the arrival of the blossoms, a large data set of temperatures is used – as the flowers will appear earlier if temperatures rise highly in spring. If it's warmer than usual in winter and autumn, the blossoms can be delayed.
Extreme weather is also a factor – unusual patterns last year meant some trees were blossoming in October, well before the usual season.
Woman in kimono take photos under a cherry blossom trees in full bloom during cherry blossom season in Maruyama park, Kyoto. Photo / Getty Images
In Japanese culture, the cherry blossom is a symbol of the fragility of life – as the blooms only last around a week before they start falling off the trees.
The season also marks a time of change, as it coincides with the start of the business year, when many university graduates begin their first full time jobs and others shift into new positions.
