Abstract
This paper summarizes recent efforts on Observing System Evaluation (OS-Eval) by the Ocean Data Assimilation and Prediction (ODAP) communities such as GODAE OceanView and CLIVAR-GSOP. It provides some examples of existing OS-Eval methodologies, and attempts to discuss the potential and limitation of the existing approaches. Observing System Experiment (OSE) studies illustrate the impacts of the severe decrease in the number of TAO buoys during 2012-2014 and TRITON buoys since 2013 on ODAP system performance. Multi-system evaluation of the impacts of assimilating satellite sea surface salinity data based on OSEs has been performed to demonstrate the need to continue and enhance satellite salinity missions. Impacts of underwater gliders have been assessed using Observing System Simulation Experiments (OSSEs) to provide guidance on the effective coordination of the western North Atlantic observing system elements. OSSEs are also being performed under H2020 AtlantOS project with the goal to enhance and optimize the Atlanticin-situnetworks. Potential offuture satellite missions of wide-swath altimetry and surface ocean currents monitoring isexplored through OSSEs and evaluation of Degrees of Freedomfor Signal (DFS). ForecastSensitivity Observation Impacts (FSOI) are routinely evaluated for monitoring the oceanobservation impacts in the US Navy’s ODAP system. Perspectives on the extension ofOS-Eval to coastal regions, the deep ocean, polar regions, coupled data assimilation,and biogeochemical applications are also presented. Basedon the examples above,we identify the limitations of OS-Eval, indicating that themost significant limitation isreduction of robustness and reliability of the results due to their system-dependency.The difficulty of performing evaluation in near real time is also critical. A strategy tomitigate the limitation and to strengthen the impact of evaluations is discussed. Inparticular, we emphasize the importance of collaboration within the ODAP community formulti-system evaluation and of communication with ocean observational communitieson the design of OS-Eval, required resources, and effectivedistribution of the results.Finally, we recommend further developing OS-Eval activities at international level withthe support of the international ODAP (e.g., OceanPredict and CLIVAR-GSOP) andobservational communities.
