10:45 AM - 11:05 AM
[ACG40-06] Redesigning the Tropical Pacific Observing System (TPOS) to enhance climate prediction
★Invited Papers
Keywords:tropical, ocean, assimilation, observations
Because ocean variability in the tropics readily interacts with the overlying atmosphere, spreading its influence over a wide latitude range, observations of ocean conditions and air-sea fluxes in the tropics underpin global prediction on subseasonal to interannual and longer timescales. These observations also serve to evaluate and guide improvement of the forecast models and the essential assimilation they power.
While the observing system elements originated as projects based on particular technologies (especially Argo, the moored arrays, and the satellite constellation), integrating these diverse data sources into a coherent picture requires assimilation through a physical model that can make effective use of their complementary strengths. Broadly, satellites give global coverage with horizontal detail, moorings sample across timescales and provide statistical confidence, allow co-located ocean-atmosphere observations, and enable direct velocity observations, while Argo resolves fine vertical structure, describes salinity variability, and connects tropical ocean conditions to the subtropics. Since most users of the observing systems do not work with the original data directly, but get it as the output of the assimilation, assimilation must be seen as an essential element of the observing system.
The international TPOS 2020 project was formed in 2014, initially spurred by the decline of the two main Pacific moored arrays (TAO and TRITON). TPOS 2020 took this as an opportunity to redesign the entire system to take better advantage of the complementarity of the main observing technologies, and to develop a structure to evaluate and introduce future technological advances. The redesigning was implemented as a collaboration among researchers and stakeholders from various disciplines, and was a forerunner of the spirit of “co-design” which is highlighted in the UN Decade of Ocean Sciences starting in 2021. Two in situ process studies were recommended to explore the potential of coming observational advancements and sampling strategy to address model weaknesses (vertical mixing in the eastern Pacific cold tongue, and air-sea fluxes over the western warm pool); these will be going in the water beginning in 2026.
Many parts of the backbone redesign are now beginning to be implemented, including the assimilation. Assessment of the end-to-end system is under way, focused especially on the effectiveness of the new observational strategy to improve reanalyses and forecast products. This coordinated multi-system ocean observation impact study began as a collaboration to compare products among prediction centers at JMA, ECMWF and NOAA and has now expanded under the UN Decade Project SynObs to include other institutions. Each center will save a series of common outputs that enable direct and detailed comparison with each other and with the new TPOS observations, including at fine vertical resolutions and timescales to expose process realism and foster model advancement. The results will evaluate observational impacts (thus pointing to future adjustment of the observational strategy) and reveal the specific features that can be improved in each model.
While the observing system elements originated as projects based on particular technologies (especially Argo, the moored arrays, and the satellite constellation), integrating these diverse data sources into a coherent picture requires assimilation through a physical model that can make effective use of their complementary strengths. Broadly, satellites give global coverage with horizontal detail, moorings sample across timescales and provide statistical confidence, allow co-located ocean-atmosphere observations, and enable direct velocity observations, while Argo resolves fine vertical structure, describes salinity variability, and connects tropical ocean conditions to the subtropics. Since most users of the observing systems do not work with the original data directly, but get it as the output of the assimilation, assimilation must be seen as an essential element of the observing system.
The international TPOS 2020 project was formed in 2014, initially spurred by the decline of the two main Pacific moored arrays (TAO and TRITON). TPOS 2020 took this as an opportunity to redesign the entire system to take better advantage of the complementarity of the main observing technologies, and to develop a structure to evaluate and introduce future technological advances. The redesigning was implemented as a collaboration among researchers and stakeholders from various disciplines, and was a forerunner of the spirit of “co-design” which is highlighted in the UN Decade of Ocean Sciences starting in 2021. Two in situ process studies were recommended to explore the potential of coming observational advancements and sampling strategy to address model weaknesses (vertical mixing in the eastern Pacific cold tongue, and air-sea fluxes over the western warm pool); these will be going in the water beginning in 2026.
Many parts of the backbone redesign are now beginning to be implemented, including the assimilation. Assessment of the end-to-end system is under way, focused especially on the effectiveness of the new observational strategy to improve reanalyses and forecast products. This coordinated multi-system ocean observation impact study began as a collaboration to compare products among prediction centers at JMA, ECMWF and NOAA and has now expanded under the UN Decade Project SynObs to include other institutions. Each center will save a series of common outputs that enable direct and detailed comparison with each other and with the new TPOS observations, including at fine vertical resolutions and timescales to expose process realism and foster model advancement. The results will evaluate observational impacts (thus pointing to future adjustment of the observational strategy) and reveal the specific features that can be improved in each model.