138
E.V. Stanev and X. Lu
Fig. 5.5 Positions of vertical profiles from Argo floats in the Mediterranean Sea and the Black
Sea since 2005. The colour scale shows water depth (m)
the spectrum for 365 days is observed in the two basins), the temporal variability
in the Black Sea and Baltic Sea is very pronounced also at intra-seasonal (between
several months and one year) and interannual periods (Fig. 5.4).
The pronounced seasonal variability of the sea level in the Mediterranean Sea
(the location used here is in the Ionian basin) is indicative for the role of heat and
water fluxes at sea surface, the later have also a very clear seasonal variability. In
the two estuarine basins the temporal variability is not as ‘monochromatic’, which
results from the variations in the transports in the straits caused by the atmospheric
forcing (e.g., wind), as well as by the less periodic river runoff. This strait control
is a crucial factor shaping the variation of the sea level in the two estuarine basins
considered here.
An important element of ocean circulation that the satellite altimetry, even combined with numerical modelling, could not resolve well was the subsurface circulation. This only became possible with the help of profile data from gliders and Argo
floats (Fig. 5.5). Argo floats are usually programmed to execute several-day-long
cycles and to drift at a neutral parking depth, measuring temperature and salinity
profiles up to the surface and transmitting the data to the Argos satellite system
(Korotaev et al. 2006; Poulain et al. 2007; Menna and Poulain 2010). Using newly
available profile data overcomes the traditional drawback of the previous knowledge
on the motion of the intermediate and deep waters, which was almost entirely based
on sporadic direct observations. As shown recently by Taillandier et al. (2010), assimilation of profile data together with satellite altimeter data of sea level anomaly
substantially improved the estimates and forecasts of the Mediterranean circulation. Unfortunately, the use of such platforms in the Baltic Sea is prevented by the
dominating shallow depths, requiring alternative devices to resolve baroclinic processes.
E.V. Stanev and X. Lu
Fig. 5.5 Positions of vertical profiles from Argo floats in the Mediterranean Sea and the Black
Sea since 2005. The colour scale shows water depth (m)
the spectrum for 365 days is observed in the two basins), the temporal variability
in the Black Sea and Baltic Sea is very pronounced also at intra-seasonal (between
several months and one year) and interannual periods (Fig. 5.4).
The pronounced seasonal variability of the sea level in the Mediterranean Sea
(the location used here is in the Ionian basin) is indicative for the role of heat and
water fluxes at sea surface, the later have also a very clear seasonal variability. In
the two estuarine basins the temporal variability is not as ‘monochromatic’, which
results from the variations in the transports in the straits caused by the atmospheric
forcing (e.g., wind), as well as by the less periodic river runoff. This strait control
is a crucial factor shaping the variation of the sea level in the two estuarine basins
considered here.
An important element of ocean circulation that the satellite altimetry, even combined with numerical modelling, could not resolve well was the subsurface circulation. This only became possible with the help of profile data from gliders and Argo
floats (Fig. 5.5). Argo floats are usually programmed to execute several-day-long
cycles and to drift at a neutral parking depth, measuring temperature and salinity
profiles up to the surface and transmitting the data to the Argos satellite system
(Korotaev et al. 2006; Poulain et al. 2007; Menna and Poulain 2010). Using newly
available profile data overcomes the traditional drawback of the previous knowledge
on the motion of the intermediate and deep waters, which was almost entirely based
on sporadic direct observations. As shown recently by Taillandier et al. (2010), assimilation of profile data together with satellite altimeter data of sea level anomaly
substantially improved the estimates and forecasts of the Mediterranean circulation. Unfortunately, the use of such platforms in the Baltic Sea is prevented by the
dominating shallow depths, requiring alternative devices to resolve baroclinic processes.