The initial target of the ARGO program was a data coverage of 1 float per 3x3° grid cell and month over the global ocean. This data coverage is deemed to be sufficient to resolve many of the important global climate signals and support the enhanced real-time requirements of operational modeling applications in oceanography and meteorology.
The Argo float distribution reveals that the network density nearly meets the initial target through the conscientious efforts of all involved partners. However, at present time some parts of the global array are already over-sampled while others are still under-sampled. There exists a marked northern hemisphere bias in data coverage while the Southern Ocean is still lacking data. This bias is partly due to disparities in availability of research vessels for certain areas in a given year but also due to convergences and divergences of the oceanic flow field. Partly it is also due to diffuse and uncoordinated decision processes for deployments permitting a slight domination of individual interests of partners over the ARGO program target. Therefore, Euro-Argo needs to evolve and sustain an effective oversight structure within the existing international framework which guides partners in their decision where to deploy floats and provides assistance in the question how to get the floats to these areas.
- To maintain and improve the system, it is essential to continuously monitor the array from an engineering point of view, in order to assess instrumental performance and to detect early on any dysfunction. It is necessary to consider the sensors accuracy and stability (as well as all other performance indicators), mission parameters, energy budgets, transmission power, rate and causes of failure, etc...
- At sea monitoring activities are also needed to detect anomalies that may impact a fleet of floats. When a fleet start to be large (a few hundred of floats) it's impossible to scrutinize each float behavior to detect such anomalies. It is therefore important to set up systems that raise automatically alarms on changes in float status and provide an easy access to all the technical information that can then be analyzed by engineers or scientists.