In early June 2002, the 21,000-ton supply vessel Magdalena Oldendorff, after supplying a number of Russian research stations in Antarctica with food and equipment, became trapped in the thickening sea ice along the Antarctic continent. Bound for Cape Town, South Africa, the ship was stranded with a 28-person crew and 79 Russian scientists. The ship drifted with the ice for 350 kilometers (220 miles) before calling for assistance on 11 June. Temperatures had fallen below 30°C (22°F), and frequent blizzards with winds above 60 knots (69 mph) buffeted the ship.
|Plowing through rough seas, the SA Agulhas heads toward the ice-bound Magdalena Oldendorff on 23 June. (Photo by Agulhas captain Kevin Tate, courtesy of Smit Marine South Africa.)|
In response to the request for help, the South African ship Agulhas left Cape Town on 16 June carrying two rescue helicopters. The South African Weather Service provided the meteorological support for the rescue mission using the Antarctic Mesoscale Prediction System (AMPS)an experimental real-time system developed by scientists at Ohio State University and NCAR and supported by NSFs Office of Polar Programs and its Division of Atmospheric Science. AMPS is based on a polar version of the Penn State/ NCAR Mesoscale Model, version 5 (Polar MM5), developed over the past decade or so under the leadership of David Bromwich (Ohio State) and Ying-Hwa Bill Kuo (NCAR).
According to Ian Hunter, manager of marine services of the South African Weather Service, AMPS proved extremely useful in support of the Agulhas rescue mission. For example, on Sunday evening, 23 June, the Agulhas reported northwest winds of 60 knots, wave heights of 12 meters (39 feet), an air temperature of 3°C (27°F), and heavy snow, with ice accumulating on the superstructure. According to Hunter, the development and motion of the intense 934-millibar low-pressure system, which caused much discomfort aboard the Agulhas, was very well predicted by AMPS. A forecast of the storm was available early Saturday morning, providing a lead time of 39 hours.
Using a window of slightly less cold and stormy weather, the two helicopters from the Agulhas airlifted 69 people from the Magdalena Oldendorff on 27 and 28 June.
Two days later, another fierce storm approached. Strong katabatic (downslope) winds averaged 60 knots at the Magdalena Oldendorff and blowing snow reduced visibility to less than 50 m (160 ft), holding the helicopters on deck. AMPS correctly predicted a brief break in the weather on 1 July, and the last non-essential personnel were rescued just before the storms resumed and the Agulhas headed home.
This support of the rescue ship Agulhas was not the first Antarctic rescue supported by AMPS. In April 2001, an international team used AMPS forecasts in support of the late-season medical evacuation of American physician Ronald Shemenski.
Adapting MM5 for Antarctica
AMPS is a success story in many ways, not least as a collaboration between Bromwichs group at Ohio State and Kuos group at NCAR. Adapting MM5 to Antarctica was not a simple task, because the physics in the model had been developed and tested over the years on tropical and mid- latitude weather systems and were not suitable for polar regions. Bromwich and his group added several features: appropriate physics for fractional sea ice coverage, a version of the National Centers for Environmental Prediction (NCEP) Eta models scheme for depicting the planetary boundary layer, and the radiation scheme from the NCAR-based Community Climate System Model, using data drawn from AMPS microphysics.
In order to resolve the topography of Antarctica, which affects the weather of the region so dramatically, a series of nested grids with resolutions of 90, 30, 10, and 3.3 km (or about 56, 19, 6, and 2 mi) was incorporated in the Polar MM5, with the finest grid located over the McMurdo area. Each run begins with data from the operational NCEP AVN model, then takes into account staffed and automatic surface observations, radiosonde data over Antarctica, and satellite-derived wind observations.
The running of an experimental research model in real time has been useful not only to operational forecasters and missions such as the ones above, but also because of the opportunity it provides for regular feedback. Running the model every day instead of only for selected cases gives researchers a much better idea of the models strengths and weaknesses, including biases. The success of AMPS also shows that a modeling system does not have to pass the rigorous standards of reliability and timeliness of a truly operational system in order to be valuable to users. In fact, as pointed out by NSFs Erick Chiang in a recent international Antarctic conference, there are definite advantages to making a research model available on a real-time experimental basis. Such a system is flexible and can be quickly modified in response to input from end users. New versions of the model and new products derived from the model can be implemented without a formal approval or a lengthy testing-and-evaluation period.
A vehicle for tech transfer and partnership
I am currently participating in two National Research Council (NRC) studies, the Committee on NASA-NOAA Transition from Research to Operations and the Committee on Partnerships in Weather and Climate Services. The AMPS story has important implications for both of these studies.
|The SA Agulhas heads north on 1 July after completing the rescue of the crew and scientists aboard the Magdalena Oldendorff. (Photo by Sgt. Major Dave Owen, South African Air Force, courtesy of Smit Marine South Africa.)|
The transition committee is looking for ways to speed up the often-lengthy process in getting discoveries from research into operations. AMPS illustrates one method of doing this, in which experimental model forecasts are made available to end users in real time to supplement the information they get from operational sources. The close relationship between the end users and the researchers benefits both groups and results in a more rapid increase of scientific understanding as well as a more accurate forecast system.
The NRC partnerships committee is looking at ways to strengthen interactions among the government, academia, and the private sector. AMPS is an example of a fruitful partnership between the U.S. government (represented by NCEP), academia, and foreign governments (South Africa). NCEP plays an essential role by providing in real time the AVN gridded analysis and forecast data. The academic community (represented by Ohio State and NCAR) provides the research and development of the modeling system. And the end users of AMPSrepresented in the Agulhas example by the South African Weather Service, and more generally by the NSF Antarctic Program, SPAWAR (Space and Naval Warfare Systems Command) forecasters at McMurdo, and many private-sector meteorologistsprovide timely feedback to the researchers. All of this is done in a very informal way, without any written agreements or formal obligations.
Modern information technology (e.g., the World Wide Web) has been essential in enabling this successful technology transfer and scientific advancement. NCAR obtains the
real-time AVN data via an NCEP anonymous ftp server and in turn puts the AMPS forecasts on the Web for the world to view and use (see On the Web).
Students from Ohio State who helped develop improved versions of AMPS have been visiting McMurdo and interacting with forecasters there. They bring back valuable feedback and experience that lead to further improvements in the model and its products. In the process, they become much better prepared for careers in operational or research meteorology.
Edited by Bob Henson, email@example.com
Prepared for the Web by Carlye Calvin
Last revised: Monday, December 30, 2002 11:00 AM