For centuries in Japan, poets have both lamented and extolled the fleeting beauty of cherry tree blossoms, the quintessential symbol of spring.
Today, people are turning to apps instead of verses to enjoy the blooming, which can be as brief as a week. One way to celebrate the blossoms is through "hanami," which means "flower viewing." It refers to picnicking under the blossoms, often with copious amounts of alcohol. It's a national pastime.
Such is the country's passion for cherry blossoms, known as "sakura," that the state-run Japan Meteorological Agency once deployed a supercomputer that crunched temperature, elevation and other data to predict when and where they begin and peak. Articles still discuss the agency's mathematical equations to predict the pink explosions.
The agency provided cherry blossom forecasts for over half a century, based on sample trees and historical records, but stopped in 2009 to focus on other services. Since then, companies have stepped in with forecasts of their own and now compete to produce the best smartphone apps for timing hanami.
One of the latest is a crowdsourced feature called Sakura Channel, part of the popular Weathernews Touch app for iOS and Android, which has been downloaded 13 million times. It provides forecasts, based on user reports, for when cherry blossoms will bloom at 700 famous viewing locations across Japan. Users can see hanami calendars and get alerts about when their favorite groves of cherry trees will burst into pink-white flowers.
They can also choose from preferences such as public parks, cherry-lined roads and spots known for nighttime revelry under the boughs. A "sakura simulator" shows a low-res view of pink petals gradually taking over cities such as Tokyo as users click through the calendar from late March through early April, the usual season for sakura.
The app was developed by Weathernews, a climate information company that has also distributed about 1,000 spherical "pollen robot" sensors that can detect airborne pollen, useful for forecasting the hay fever season.
"Our app is special in that it uses information from ordinary people. About 8 million users are sending us photos and weather reports of every sort," a Weathernews spokeswoman said.
"Some other developers simply tell you whether trees are blooming or not in each prefecture, but about 11,200 users across the country are sending us information about local cherry trees and we take advantage of that input."
Weathernews has also introduced a "virtual hanami" feature showcasing time-lapse photos taken with smartphones and panoramic videos of cherry blossoms captured with Ricoh's 360-degree Theta m15 camera.
Not to be outdone, Navitime Japan is offering twice-daily cherry blossom updates for more than 1,000 sites across the country. It has added the information to its popular smartphone and feature phone apps, which help Japanese navigate subway and train connections as well as roads and highways. They also provide location-specific info such as the availability of parking spots, and of course travel directions.
Japanese websites, meanwhile, abound with information on where to see blossoms, from timetables of current predictions compared to average flowering dates to lists of live cams trained on petals.
For instance, Weather Map, which began issuing predictions in 2010, has PC and mobile sites with detailed information including temperature charts, blooming graphs and a map of Japan showing the front of cherry blossoms moving up the archipelago from south to north. It uses observations of about 50 sample trees to make predictions, according to a Weather Map spokeswoman.
It also has a cherry blossom outlook and maps for most cities. The site predicts the flowers will be at full bloom in Tokyo on March 31 after opening three days earlier than the average date. The traditional cherry "weathervane" for the capital is a grove of old cherry trees at Yasukuni Shrine, a politically controversial Shinto sanctuary that honors soldiers killed in past wars.
Tim Hornyak covers Japan and emerging technologies for The IDG News Service. Follow Tim on Twitter at @robotopia.