The use of Argo floats as virtual moorings for monitoring the South Baltic Sea

The Argo float measurement network is increasingly effectively covering internal seas and shelf areas. In this paper, a specific approach to using Argo floats as ‘virtual moorings’ within the conditions of the Baltic Sea is presented. Following a series of successful deployments with standard configurations, it was decided that the settings forcing the float to stay at the bottom between profiles should be tested. This significantly reduced the drift of the float and allowed measurements to be made in a limited water area for a longer time. The data obtained from Argo floats used as virtual mooring can be a valuable source for monitoring and analysing the hydrology of individual basins of the Baltic Sea. The results show that the temporal and spatial variability of the observed fields of temperature, salinity, and other properties of seawater is very high. More data are needed to correctly determine the mean properties of the basins and their temporal variability. Therefore, Argo floats can be a source of efficient and inexpensive hydrographic data for shallow seas such as the Baltic.