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May 1998

Taiwan: NCAR lands a new aviation safety project in Asia


Three of the principals in the Taiwan project: Rich Wagoner (RAP), Jordan Powers (MMM), and Bill Mahoney (RAP). (Photo by Carlye Calvin.)

As one major aviation weather project draws to a close in Hong Kong, the Research Applications Program and the Mesoscale and Microscale Meteorology Division are launching a new one in Taiwan. Under the $11-million program, NCAR will modernize Taiwan's aviation weather information systems over the next five years.

"This is a long-term technology exchange program," says RAP's Bill Mahoney, program manager for the Taiwan project. Between now and 2003, RAP and MMM will

Later, the program could expand to include an even wider range of weather products.

"This project is highly leveraged by other work going on in RAP and MMM," says Bill. For instance, the results of FAA-supported efforts at NCAR to detect icing and turbulence in flight should make their way into the Taiwan weather system. The MM5 work builds on previous efforts supported by NSF, Hong Kong, and the FAA.

The three airports being served by the new RAP/MMM aviation safety project in Taiwan lie at opposite ends of the island. Sungshan and Chiang Kai-Shek airports are in the Taipei area, on the island's north tip, while Kaohsiung is several hundred kilometers to the south. Seven Doppler radars, styled after the WSR-88D models in place across the United States, are being deployed around the island. The RAP/MMM system will serve the entire Taiwan flight information region.

As RAP brings its expertise to Asia, it's benefiting from a scramble among the region's urban powers, each of which hopes to become a regional aviation hub. "There's a lot of competition among Hong Kong, Taiwan, and now Singapore," says Bill. Also, several major air disasters in and near Taiwan over the past two years have raised the profile of aviation safety on the island.

This is the second major collaboration announced in recent months between Taiwan and UCAR/ NCAR. Currently awaiting approval from the U.S. State Department is a proposal to launch a constellation of eight Global Positioning System microsatellites with Taiwanese funding and UCAR-based science and technology. (See the February 1998 issue of Staff Notes Monthly.

Equipment first this time

Although the tropical venues are similar--and just 800 kilometers (500 miles) apart--the tasks faced by NCAR in Taiwan are substantially different from those it tackled in Hong Kong. An entirely new airport was being built in Hong Kong, so RAP had to gather extensive data to analyze the local weather risks before proceeding to design a system that would detect, forecast, and warn pilots of terrain-induced turbulence and wind-shear hazards. "We had a basic science problem to solve," says Bill. For the established airport sites in Taiwan, "it's more tech transfer--getting the systems developed, ported, and tuned--although there are still a number of science issues."

The Low Level Windshear Alert Systems (LLWAS) found at many major U.S. airports will be deployed at two Taiwanese airports:

No LLWAS unit will be used at the airport at Kaohsiung, an industrial city on the island's south coast, because there is insufficient land and space available for a network of anemometers around the airport. Instead, an existing aircraft surveillance radar at Kaohsiung will be retrofitted with a processor to detect low-level wind shear using new software from the Massachusetts Institute of Technology Lincoln Laboratories. The software "attaches to the surveillance radar and makes it work like a terminal Doppler weather radar," says Bill. This approach is being used by the FAA to provide wind-shear protection at U.S. airports that lack terminal Doppler weather radars.

For RAP, the heart of this project is to create a new weather-information system to serve growing aviation needs at airport terminals and throughout Taiwan's airspace. Once the system is running, air traffic controllers and managers will have access to high-resolution information on aviation variables including wind, temperature, icing, turbulence, ceiling, and visibility. Airlines and pilots will be able to access a variety of real-time products from an Internet-based server restricted to authorized users, who will be able to sketch a flight route within Taiwan's airspace and obtain hazardous-weather warnings as well as routine data and forecasts along that route.

As in Hong Kong, the most serious large-scale weather threats in Taiwan are tropical cyclones that sweep in several times each year from the western Pacific. "Typhoons are always a big threat--it's a constant problem," notes Bill Kuo (MMM). Strong winds blowing over the mountainous terrain can produce turbulence, although it's expected to be less severe at Taiwan airports than at Hong Kong's Chek Lap Kok airport because Chek Lap Kok is closer to steep mountains. Downbursts from thunderstorms are another frequent risk that RAP's system will be watching for.

A new playing field for MM5

In MMM, scientists who've been exploring how to simulate and analyze the weather on finer and finer scales are excited to work with RAP on the Taiwan project. The incarnation of the MM5 forecast model applied here will predict wind, temperature, and other common (and not-so-common) meteorological variables at frequent intervals on a nested set of regional grids. The model zooms in from a resolution of 135 km (85 mi) over an area spanning half of Asia and the western Pacific to as tight as 5 km (3 mi) over a zone the size of the Taiwan flight information region. In contrast, the MM5 is operating in real time in Hong Kong at a top resolution of 18 km (12 mi).

"This is truly an advancement in real-time use of the MM5; it's pushing the application of a state-of-the-art numerical weather prediction system to new levels," says Jordan Powers, who is managing this portion of the Taiwan project. Taiwan's Central Weather Bureau (CWB) has been running a nested-domain version of the MM5 in real time for a few months (their forecasts are posted on the Web). Other real-time MM5 operations are being conducted by the U.S. Air Force and a number of universities.

Thanks to the advancement of new model initialization techniques by scientists such as MMM's Xiaolei Zou, other kinds of data may be incorporated into the Taiwan forecasting system. One approach, three-dimensional variational data assimilation (3DVAR), has the potential to significantly improve the MM5's initial conditions with data provided by satellites, such as precipitable water and radiance.

Piecing it together

One of the side benefits of the Taiwan project could be to forge stronger relations between the CWB, which handles public forecasts, and the Civil Aeronautics Administration (CAA), which oversees aviation weather. "They're completely separate organizations," says Bill Mahoney. "CAA is our sponsor, but we see this program as bridging the CAA and CWB. For the MM5 to work efficiently for aviation and public uses, it has to run at the CWB."

Because Taiwan does not have a formal diplomatic relationship with the United States, the collaboration between UCAR and the CAA has to be established through an agreement between the American Institute in Taiwan (the equivalent of a U.S. embassy) and the Taipei Economic and Cultural Representative office (the equivalent of a Taiwanese embassy in the States). There are also cultural differences that only time and visits will completely unearth. According to Bill, "The business culture in Taiwan is closer to American than Chinese. In Hong Kong, it was more Chinese with a British twist." •BH

So long, Hong Kong

 The runways at Chek Lap Kok International Airport will feel the first rubber from commercial aircraft on 6 July, when Hong Kong's new $20-billion airport opens for business. Should any high winds or tropical cyclones be waiting in the wings to spoil opening day, a first-class warning system for turbulence and wind shear is in place to sound the alarm.

An artist's impression of the new Hong Kong airport and vicinity as it might look in the year 2040 with airport-related urban growth. (Copyright Hong Kong Economic & Trade Office.)

The airport debut is the climax of a five-year program in RAP to analyze the site's weather risks and develop a package of hardware and software to keep passengers as safe as possible. The project involved over 30 staff from RAP, ATD, MMM, and collaborating universities; $16 million (U.S.) from Hong Kong for research, development, and deployment; and at least 60 round-trip flights to Hong Kong by bleary-eyed scientists, engineers, technicians, and administrators from NCAR.

At first it wasn't clear how much meteorological trouble RAP might have on its hands. The airport was to be sited at the north end of Lantau Island, only a few kilometers from a kilometer-high mountain. From a topographic point of view, it was akin to putting an international airport at Table Mesa and Broadway, hard up against the Flatirons.

The RAP team gamely accepted its challenge. In a two-year scientific study headed by Peter Neilley, tropical cyclones--and, more generally, high winds and thunderstorms--were identified as the main weather threats. Modelers led by Terry Clark (MMM), along with participants in a 1994 field study using the now-retired NSF/NCAR King Air, examined what kinds of turbulence and wind shear might exist near the airport when the winds blow over Lantau's peaks. They found that virtually all of the turbulence near Chek Lap Kok appeared to be mechanical--the kind formed as flow over obstacles dissipates into smaller, weaker eddies--rather than the amplified, wave-induced turbulence that occurs under certain conditions in places like Boulder.

The final alert system integrates Doppler radar, anemometers near the runways and on Lantau Island, "fuzzy logic" algorithms, and the MM5 to spot and warn for conditions that point toward turbulence.

NCAR completed the program and handed over the system last July. The Hong Kong Observatory is currently developing a program of verification and system enhancement that will begin about the time the new airport opens. It's likely that NCAR will participate. "We'll do follow-on work on a year-by-year basis," says project manager Bill Mahoney. "It'll be a state-of-the-art facility for a long time." •BH

On the Web

Hong Kong International Airport home page
RAP Annual Scientific Report 1997
UCAR Highlights, fall 1996

The expatriate factor: Going back to Taiwanese roots

 In the summer of '69, Celia Chen was new to America. She'd just come over from Taiwan to help her brother, his wife, and their newborn boy. The plan was for her to take the baby to Taiwan, where grandparents would look after him while the parents got established in their U.S. careers. "But the parents changed their minds," says Celia.

Celia Chen and Bill Kuo. (Photo by Carlye Calvin.)

So did she. Her visit to the States has now lasted nearly 30 years. Celia got a degree in mathematics from Fort Lewis College and, in 1972, a job as a computer programmer at NCAR. Every few years she'd journey back to her native island, but each trip brought to life Thomas Wolfe's rueful observation, "You can't go home again."

"Taiwan is my motherland, but Boulder is my home," says Celia. "Even when I'm over there, they look at me as if I'm half-Chinese, half-American. Even my brother in Taiwan teases me and says 'You used to be my sister. Now you are my American sister.' "

At least, she adds, "I don't have an American accent when I speak Chinese."

Celia will be seeing more of Taiwan over the next few years. She's been designated a technical liaison for the RAP/MMM airport project. In addition to her involvement in the project's software development, Celia will translate official documents and do some informal translating at quarterly review meetings, whose location will alternate between Boulder and Taipei.

Most Taiwanese speak perfectly fine English in the meetings, says Celia, who serves as RAP's de facto expert in Chinese (she has taught several informal courses for divisional staff). However, she notes that it's easier for a roomful of decision makers in Taiwan to use Chinese than English when highly complex matters are on the table.

To prepare written documents, Celia is using the Chinese character-based versions of Windows 95 and Microsoft Word. They allow users to spell complex words by first stringing together characters from a mock keyboard of about 50 phonetic building blocks and then choosing the complete character from a set of sound-alike possibilities deduced by the system.

At a gathering for Taiwanese students during her first uncertain summer in Denver, Celia happened to meet a young meteorologist named Chin-Yen Tsay. He would soon become the first Ph.D. to return to Taiwan to teach meteorology, after obtaining a doctorate from the University of Utah. Afterward, he did a year of postdoctoral research at NCAR with Akira Kasahara. Tsay is now one of the top science figures in Taiwan: as vice chair of the National Science Council (NSC), he oversees the island's space and natural science programs.

Bill Kuo (MMM), who runs the COSMIC Project Office and will help oversee data assimilation for the airport weather project, took his first course in numerical weather prediction from Tsay in 1977. At the time, Bill wasn't set on meteorology, but the subject had drawn him in early--on 7 August 1959, to be exact.

"I was six years old, and there was a big typhoon in central Taiwan. I remember waking up early in the morning to discover that all the farms in our area had been destroyed. The good soil was gone--all you had was gravel. I was impressed." Still, even after starting his bachelor's program in meteorology, at National Taiwan University, Bill kept an eye on the option of someday taking over his father's wholesale textile business.

Tsay changed all that. In the 1970s, says Bill, "we'd been kind of detached in Taiwan from the modern meteorology going on [in the States]." But in Tsay's course, Bill found himself punching cards and running an equivalent barotropic forecast model (one vertical layer, 900 total grid points). "It's the first time I actually saw weather patterns changing in a model. I was really excited and decided to stay with meteorology." Bill went on to the South Dakota School of Mines and Technology for his master's and to Penn State for his doctorate, coming to NCAR in 1981.

Taiwanese meteorology reentered Bill's life in 1985. Tsay and several other compatriots came to NCAR and proposed a severe-weather field study in Taiwan. Held in May and June 1987, the Taiwan Area Mesoscale Experiment (TAMEX) made a big scientific splash. "I'm sure there've been at least 50 papers published out of TAMEX," says Bill. Afterward, the participants maintained close scientific collaboration through yearly workshops and a major 1993 review.

Bill takes pride in knowing that the project made a difference to the meteorology community in his homeland. "I still remember watching students from the Taiwan universities giving presentations at the [1993] TAMEX review," recalls Bill. "I felt very satisfied because I knew TAMEX had produced a quantum jump in the quality of their research." •BH

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Edited by Bob Henson, bhenson@ucar.edu

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