More typhoons than usual have threatened Taiwan this year, which is bad news for most residents, but a source of sustenance for an elite group of scientists who love nothing more than to chase the storms.
The scientists are part of Dotstar (Dropwindsonde Observations for Typhoon Surveillance near the Taiwan Region), a research project started in 2003 involving 14 organizations, from Taiwan’s Central Weather Bureau (CWB) to the US-based National Oceanic and Atmospheric Administration.
Their mission: Get on a specially equipped plane whenever a typhoon approaches and track it at 13,100m to help forecasters figure out how the storm will behave.
The operation is the first and only one in the northwestern Pacific and East Asia region to engage in aircraft surveillance of typhoons.
“An intensive survey allows us to obtain more thorough data on how typhoons develop and how they could interact with each other,” said Chen Hsin-gan, a member of the project and a researcher at National Taiwan University (NTU).
Rarely have the scientists been busier than over the past couple of weeks, when they flew four missions to follow Typhoon Tembin to the southeast and then southwest to track Typhoon Bolaven further away to the northeast between Tuesday last week and Monday.
The two storms engaged in some atmospheric gymnastics, with Bolaven pulling Tembin back toward Taiwan after it went out to sea on Friday — a phenomenon known as the Fujiwhara effect.
Flight crews of three meteorologists and two former air force pilots have been following the storms’ every movement, spending five hours at a time flying above and even at the very heart of the typhoons to collect data, project member and CWB Weather Forecast Center director Cheng Ming-dean (鄭明典) said.
Cheng said that when the plane, a re-equipped business jet operated by Taiwan-based Aerospace Industrial Development Corp, is above the storm, thermos-shaped devices called “dropwindsondes” are released into its bands.
Usually around 15 of these 40cm-long measuring instruments are used to detect humidity, wind direction and velocity, making them a valuable resource of information that the CWB can draw on to determine a typhoon’s often fickle path.
After each flight is completed, all the information collected is sent to the team’s lab to identify the typhoon’s steering flow in different time frames.
“It’s the most direct scientific data we can get, and we share our analysis with partners in Japan, the US and Europe,” Cheng said, adding that the project costs Taiwan NT$30 million (US$1 million) each year.
Lin Po-hsiung (林博雄), an NTU professor and the project’s co-principal investigator, said that each mission can improve the forecasting accuracy of a typhoon’s path within the next 24 hours by 20 percent on average for the project’s US partners.
Somewhat surprisingly, the operation only improves Taiwan’s forecast accuracy by about 10 percent, Lin said, because its weather bureau’s computers do not run the same model as their US counterparts and crunch data relatively slowly.
However, that should change later this year when the weather bureau receives a supercomputer it has ordered, Lin said.
According to the CWB, the new system’s speed will enable weather forecasters to run more than 20 weather patterns comprised of large numbers of variables at one time, which should help enhance the mission’s output in real time.