1) The proposal must be presented and signed by a group of researchers from different countries? Can be presented and signed by a group of researchers from one country only, or by one researcher?

The proposal must have the consent of a group of researchers from different countries. Can be presented by one researcher indicating the members (with countries and expertise) of the Study group. 

2) The proposed issue should necessarily produce recomendations that represent an advance for the whole oceanographic community or it can be produce new recomendations to be applied to some regional community?

If it is a regional problem, that's fine. Could the solution perhaps be exported to a wider level later?

3) This type of proposals for IAPSO Best Practice Study Groups will take place in further years too?

We plan to lunch a call for IAPSO Best Practice Study Groups every two years to support 2 groups during this time.