Category Archives: Baltic Sea

Spurious Mixing & Inflows

In a GMD highlight paper we report on spurious mixing retarding the representation of deep saline inflow events in a high-resolution general ocean circulation model of the Blatic Sea (pg. 1723, Figure 14). Here, we provide an additional visualization.

The problem arises wherever relatively fast bottom currents meet steep topography such as in between Sweden and Bornholm.

Location of animated section. The blue color denotes water depth.
Animation of salinity (color), surface mixed layer (dashed black line) and vertical velocities (white and grey contours for upwards and downwards velocities in units meter per day, respectively).

Retracing Cyanobacteria Blooms in the Baltic SEA

In late summer, massive blooms and surface scums of cyanobacteria emerge regularly in the Baltic Sea. The bacteria produce toxins and add bioavailable nitrogen fixed from atmospheric nitrogen to an already over-fertilized system. Despite their critical role the controls on cyanobacteria blooms are not comprehensively understood. Here we add to the discussion by retracing the origins of blooms observed from space.

Movie 1 shows observations of blooms from space.

Movie 1. Cyanobacteria blooms as detected from space by the Swedish Meteorological and Hydrological Institute (Hansson 2007).
Movie 2. Backtracing of the July 11th cyanobacteria blooming event. The movie starts in May showing water parcels marked with cyan crosses that will bloom on July 11th. Grey circles denote water parcels that fail to bloom on July 11th. Copper to black background color coding denotes simulated surface mixed layer depth. Mixed layer depth and velocities used to calculate the movement of parcels are taken from a MOMBA hindcast simulation.