Rationale and use of the CP2 Testbed in Brisbane, Australia

The Australian Bureau of Meteorology Research Centre (BMRC) has acquired the CP2 weather radar under the auspices of a joint project with the National Center for Atmospheric Research (NCAR) for the purposes of hydrometeorological research activities within Australia. CP2 was first built in the 1970's for hail and precipitation research in the National Hail Research Experiment undertaken in Colorado. Although CP2 has not been employed for a number of years in atmospheric research it remains a unique system with a dual wavelength (S and X band) and polarimetric/Doppler capability. To date the combination of dual frequency and dual-polarimetric radar has not been explored extensively in the research and especially the operational radar community.

This project aims to make use of the unique characteristics of the CP2 radar and builds on past joint activities between BMRC and NCAR. The project involves scientific and engineering contributions from both groups with emphasis on outcomes related to the nowcasting of severe weather, hydrology and weather impacting the aviation terminal area. Collaborative research is also planned with other groups including Colorado State University (CSU).

Expected outcomes from the joint research and development activities include: • Improved Quantitative Precipitation Estimation (QPE) based on radar and in-situ measurements • Improved understanding of precipitation processes with emphasis on orographic rainfall • Improved Quantitative Precipitation Forecasting (QPF) for nowcasting (0-3 hour based on radar) and very short range forecasting (0-24 numerical weather prediction NWP) • Improved hydrological modelling based on radar and NWP techniques • Development of urban 5-10 min flash flood forecasts • Improved nowcasting of convection and severe weather including occurrence of hail, low level windshear, damaging downbursts, lightning, hydrometeor particle identification • Establishment of verification procedures in QPE, QPF, weather modification and nowcasting

CP2 is located at Redbank Plains (Latitude 27°40.0' S Longitude 152°51.5' E) near Brisbane, Australia in a subtropical environment on the coastal zone of eastern Australia. Interaction between the subtropical flow and the topography is an important factor in determining the local climate and associated potential weather related threats. Catchments and river valleys within the coastal ranges have significant potential for flooding. For hydrological applications the initial focus will be producing high quality rainfall analyses and forecasts, and applying these data in a probabilistic framework to a suite of hydrological models to produce flood warning products. Real-time verification will also be an important component.

More traditional weather related products will be developed and tested by the Bureau in collaboration with other organisations. In this sense CP2 is seen as testbed for the development, testing and intercomparison of algorithms before operational use by the Bureau of Meteorology. Again the key is end-to-end systems. Processes and products will be interfaced with the Bureau operational systems to enhance the overall forecast process.