The Tropical Atmosphere Ocean Array (TAO) has been described as the "crown jewel" of the Global Climate Observation System. TAO is presently undergoing transition from a research project at the Pacific Marine Environmental Laboratory (PMEL) in Seattle, Washington to operations at the National Data Buoy Center (NDBC), Stennis Space Center, Mississippi. Transition from research to operations is part of the the National Oceanic and Atmospheric Administration's (NOAA) policy for applying the best available science and technology to meet NOAA's mission.

The TAO transition from PMEL to NDBC follows upon the successful transition of the Deep-ocean Assessment and Reporting of Tsunamis (DART) system in 2004. The TAO transition team, PMEL, NDBC, and the NOAA Office of Global Programs, agreed to a set of principles that guide the transition. Among those principles are:

• Maintain the quality and integrity of the data.

• Ensure transparency of the transition to current TAO data users, including researchers, operational centers, policy makers, and the general public.

• Use a phased approach to transition the TAO data operations first and then the technology refreshed TAO systems.

The first phase of the transition, data operations, includes data processing, quality control, and operational web services. NDBC and PMEL agreed to a test plan that formulated standardized test procedures and pass/fail criteria. In order to ensure continuity and fidelity of data before finalizing the transition, an 11-month period of parallel testing was conducted in which NDBC independently processed data, applied quality control measures, generated the TAO product suite, and compared the results to PMEL processes and products.

This paper provides the background for the TAO, and specifically for the data operations transition, describes the test plan and parallel testing, discusses the challenges and opportunities in the transition, presents preliminary results of the parallel testing, and summarizes the remaining elements of the transition.