Represent Ferry box
sea surface temperatures
the SST in the Baltic Sea?
Published on 21. September 2010

The passenger ferry “Finnmaid” and the merchant vessel “Transpaper”, equipped with a ‘Ferry Box’,  ply the Baltic Sea virtually non stop. Water temperatures are automatically taken at a water depth of about 3-4 meters every 20 seconds, and together with air temperatures sent by satellite once an hour, and immediately available in the internet at: The Baltic Sea Portal (BSP). Do they represent the statistical mean SST date as shown in shown the SST map (BSP), for the 20. Sept.2010, 17:00 hours.

There are days which show extraordinary SST variations. The two days, 20th and 21st  September 2010 may serve as an example.  The next left figure are the data from the “Finnmaid” that had been immediately net-published between the 19. Sept (Helsinki Travemünde in green) to 21. Sept. (Travemünde – Helsinki in red); here in PDF. The figure to the right shows only the journey from Travemünde to Helsinki (20/21 Sept.) and the salinity, which the BSP presented as “Temperature and salinity in the Baltic Sea 20  - 21 September 2010” . The route was east of Gotland.

During the first part of the round trip (green line), as well as on the way back to Helsinki ( red  line) the SST drop for several hours by almost 10° C.

On her out-bound trip the “Finnmaid” passed Gotland in the west of Gotland, as did the “Transpaper” on the same day, in PDF here.

The “Transpaper” sailed from Gothenburg (Lübeck) to Kami (17.09. brown), and back (18.-21.Sept. red), passing Gotland only in the west of the island. Although both vessels sailed the same route west of Gotland, and in a narrow time period (19. Sept), the SST data are very different. That is surprising , and may raise questions whether the data can be immediately be used for research.