|A BMRC radar site at the Maritime Continent Thunderstorm Experiment. (Photos courtesy of Bureau of Meteorology.)|
Australia offers unique challenges to its meteorologists, in part because of its isolation in the southern oceans. With important outdoor industries like tourism, the nation depends on good weather forecasts. But besides these forecasts for its own population, Australia has international commitments to provide weather forecasts and severe-weather warnings for some 12% of the globe--from the tropics to Antarctica.
The Australian Bureau of Meteorology faces a real challenge in meeting these commitments. Just the task of maintaining its observing systems, which are scattered across deserts and oceans, is a major endeavor. To lessen some of the pressure on the bureau and ensure a firm scientific basis for its ongoing work, the Bureau of Meteorology Research Centre (BMRC) was established in 1985. Its purpose is to conduct research on areas of long-term significance to the bureau that are not likely to be effectively covered by other organizations, either in Australia or internationally. The core areas are numerical modeling and long-range forecasting with a focus on Australasia, tropical meteorology, and meteorological observing systems. With a scientific staff of about 45, BMRC has six research groups: mesoscale meteorology, regional meteorology, medium-range prediction, climate, climate change modeling, and oceanography.
BMRC has access to all the facilities of the Bureau of Meteorology, including state-of-the-art computing facilities and meteorological observing systems and sites. In November 1997, the bureau and Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) launched the High Performance Computing and Communications Centre in Melbourne, which houses a NEC SX-4 supercomputer. The new computer has allowed a host of improvements in weather forecasting and climate modeling, supporting studies in climate change, ozone depletion, and air pollution and El Niño predictions.
The powerful El Niño of 1982-83 was a disaster for Australia, with extensive crop losses and widespread range fires. It was also a call to action for the country's climate scientists, who began to improve monitoring and modeling of the El Niño-Southern Oscillation (ENSO) phenomenon. As part of the Tropical Ocean and Global Atmosphere (TOGA) program, BMRC put buoys in the Pacific to monitor sea-surface and below-surface temperatures in the late 1980s, and computer models of ENSO were further developed. With these advances, BMRC was able to recognize El Niño conditions in 1991 and 1994 and to disseminate forecasts by early July in both years. Last year, the BMRC issued a forecast even earlier.
BMRC's Climate Group develops models and systems for prediction of ENSO and its impacts on the Australian climate. These are used by the Bureau of Meteorology's National Climate Centre to produce widely disseminated monthly Seasonal Climate Outlooks. These forecasts which cover a range of conditions, such as the onset of the wet season in northern Australia and possible drought in the eastern and southern regions. The group continues to fine-tune the seasonal outlooks to better meet the needs of farmers, e.g., by attempting to predict the variables the farmers have asked for with the accuracy and lead time they need.
Like NCAR's Kevin Trenberth, Nicholls is examining how global climate change may affect future El Niños. BMRC researchers have found that recent events created less severe droughts than past ones. Nicholls writes, "It appears that the recent, more frequent El Niño events have been offset to some extent by their being a bit less dry."
|The close relationship between Australian weather and El Niño is apparent in this figure, which correlates wheat yields (gray,in tons per hectare) with sea surface temperatures (green line, in degrees C) around northern Australia. Cool seas indicate El Niño years. (Illustration courtesy of Neville Nicholls.)|
The BMRC continues its research and development effort to improve both global and regional weather prediction models. Currently, the effort is concentrated on one of each: the Global Assimilation and Prediction (GASP) system and the Limited Area Prediction System. LAPS, which became operational in 1996, is a nested model with horizontal resolution of 70-80 kilometers. A doubly nested version, with resolution of 20-30 km, debuted last May. This is another step toward meeting the bureau's goal of attaining resolutions down to a few kilometers, with three-dimensional displays, in time for the Year 2000 summer Olympic Games in Sydney.
Prediction of cloud cover as it would be seen from a satellite is a recent BMRC research innovation that has been used in both GASP and LAPS, as well as in the Tropical Analysis and Prediction System. In a related development, BMRC scientists are collaborating with researchers at the Cooperative Research Centre for Southern Hemisphere Meteorology on the development of an ultraviolet index forecasting system. Using GASP output, they calculate a 36-hour forecast of the noon clear-sky UV index for a number of Australian cities.
|Greg Holland (BMRC), left, and Tad McGeer (In-Situ Group) with the BMRC's robotic aircraft, the aerosonde.|
For the experiment, BMRC staff developed the aerosonde, a miniature robot aircraft that can be used for long-range environmental monitoring, especially over oceans or remote areas. The MCTEX field trial--the sonde's first--was very successful. Since then, the aerosonde has been used for flights of up to 30 hours in a wide variety of experiments, with over 600 hours flown in total. The aircraft has a wing span of about 3 meters (10 feet), weighs only 14 kilograms (about 31 pounds), and is launched from a car roof. It was developed jointly by Sencon Environmental Systems (now Environmental Systems and Services) in Melbourne, the bureau, and the U.S.-based In Situ Group, with partial sponsorship from the U.S. Office of Naval Research, NOAA, the U.S. Department of Energy, and the Taiwan Central Weather Bureau.
MCTEX data continue to be the focus of a substantial research effort, which has led to significant advances in understanding tropical thunderstorms. The data have clarified the role played by island sea breezes, provided detailed cloud microphysics, and refined knowledge of the generation of clouds' electric fields. These advances have led to improved operational techniques for forecasters in the bureau's tropical offices and influenced the direction of international research on convection.
The research objective of the Darwin station is to study the four-dimensional structure, dynamics, and microphysical properties of tropical convection. Development of equipment necessary to conduct studies meeting this objective is a significant part of this program.
Among its other missions, the station provides ground validation data for the Tropical Rainfall Measuring Mission (TRMM), a joint satellite project of NASA and the Japanese National Space Development Agency. Over the last eight years, as TRMM was being planned, the station has provided support for a number of the program's related research activities. The first TRMM instruments were launched last November, and the Darwin program will be involved throughout TRMM's mission phase.