Japan’s sakura or cherry blossom season is feverishly anticipated by locals and visitors alike. Many tourists plan their entire trips around the blooms, and Japanese flock to parks in their millions to enjoy the seasonal spectacle.

In general, blooms begin as early as March in southern Kyushu and appear as late as May in northernmost Hokkaido.

In a bid to improve its forecasts, some outfits have started crowdsourcing data, including Weathernews, a firm in Chiba near Tokyo.

It relies on photos of buds sent in regularly by 10,000 citizens across the country who are registered on the company’s website and app. The company launched what they call the “Sakura Project” in 2004, signing up members who choose their own cherry tree and send pictures of its buds to the firm at regular intervals.

Just observing the bud can give surprisingly accurate information about how far the flower is from full bloom.

A sakura bud still a month from blossoming will be small and firm, but after 10 days, the tip turns slightly yellow-green, and then a darker green part emerges.

When the tip of the bud turns a faint pink, it’s just a week until bloom time.

Thanks to the project, Weathernews has accumulated data from 2 million reports on cherry flower buds in the past 15 years, which it uses to increase the accuracy of its forecasting.

It also incorporates weather data collected from its own observation devices across Japan — 13,000 locations in total, 10 times more than the official weather agency has. Weathernews employees also call around 700 parks regularly to check the growth of cherry flower buds.

The company and other forecasters also employ mathematical models and algorithms.

Japan’s Meteorological Agency stopped forecasting cherry blossoms in 2010, after more than five decades, saying other organizations were now making predictions with sufficient accuracy.

The agency does however still declare the official start of cherry blossom season by monitoring 58 so-called barometer trees.

The trees are at locations across the country, and the precise locations are considered a closely guarded secret.

Words to Learn 相关词汇

【算法】suànfǎ algorithm a process or set of rules to be followed in calculations or other problem-solving operations, especially by a computer

【晴雨表】qíngyǔbiǎo barometer an instrument measuring atmospheric pressure, used especially in forecasting the weather

日本人和游客都非常期待樱花季。很多游客按照樱花季的时间规划整个行程，还有数百万日本人会在樱花季涌入公园饱览盛景。

一般来讲，日本南部九州的樱花早在三月就开放了，而在最北部的北海道，樱花要到五月才开放。

为提高预测准确性，一些机构开始通过众包的方式收集数据，比如，东京附近千叶市的天气新闻公司。

这家公司的数据来源于1万名日本各地的市民定期发送的樱花花蕾照片。这些市民都在该公司的网站和应用程序上进行了注册。

这家公司在2004年推出了“樱花项目”，与民众签约。民众选择所要观测的樱花树，并定期将花蕾照片发送给公司。

只需观察花蕾，就能给出樱花盛开时间的准确信息，着实出人意料。

还有一个月才开花的樱花花蕾小而紧实，但在10天之后，花蕾的顶部有些许变为黄绿色，之后会呈现出深绿色。

花蕾的顶部变为淡粉色时，距离花开就只有一周了。

由于有了这个项目，天气新闻公司在过去15年间已经收集了樱花花蕾的200万份报告，公司以此提高了预测的准确性。

公司还整合了用自己的观测设备收集的天气数据，这些设备遍布日本1.3万处观测场所，比日本气象厅的观测场所多10倍。

公司职员还会定期给700个公园打电话，核对樱花花蕾的生长情况。

该公司和其他预测机构还使用了数字模型和算法。

日本气象厅在2010年终止了其持续50多年的樱花花期预测工作，称其他机构目前的预测准确率已足够高。

不过，日本气象厅还是会通过监测58棵“晴雨树”来正式宣布樱花季的开始。

这些“晴雨树”遍布日本各地，但其准确地点秘而不宣。 (Chinadaily.com.cn)