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Response of the Baltic Sea to climate change - theory and observations
Stigebrandt, A.; Gustafsson, B.G. (2003). Response of the Baltic Sea to climate change - theory and observations. J. Sea Res. 49(4): 243-256. https://dx.doi.org/10.1016/s1385-1101(03)00021-2
In: Journal of Sea Research. Elsevier/Netherlands Institute for Sea Research: Amsterdam; Den Burg. ISSN 1385-1101; e-ISSN 1873-1414, meer
Ook verschenen in:
Ohlson, M.; Omstedt, A.; Turner, D. (Ed.) (2003). Proceedings of the 22nd Conference of the Baltic Oceanographers (CBO), Stockholm, Sweden, 25-29 November 2001. Journal of Sea Research, 49(4). Elsevier: Amsterdam. 227-374 pp., meer
Peer reviewed article  

Beschikbaar in  Auteurs 

Trefwoorden
    Analysis > Response analysis
    Atmospheric forcing
    Climatic changes
    Cycles > Hydrologic cycle
    Ice cover
    Models
    Motion > Fluid motion > Baroclinic motion
    Properties > Chemical properties > Salinity
    Properties > Physical properties > Thermodynamic properties > Temperature
    Properties > Water properties > Temperature > Water temperature > Surface temperature
    Response time
    Temporal variations > Long-term changes > Sea level changes
    Temporal variations > Periodic variations > Seasonal variations
    ANE, Baltic [Marine Regions]
    Marien/Kust
Author keywords
    Baltic Sea; Kattegat; climate change; salinity; temperature; ice;rotating hydraulic control; water exchange; deep water

Auteurs  Top 
  • Stigebrandt, A.
  • Gustafsson, B.G., correspondent

Abstract
    The dynamics controlling the response of the Baltic Sea to changed atmospheric and hydrologic forcing are reviewed and demonstrated using simple models. The response time for salt is 30 times longer than for heat in the Baltic Sea. In the course of a year, the Baltic Sea renews most of its heat but only about 3% of its salt. On the seasonal scale, surface temperature and ice-coverage are controlled by the atmospheric conditions over the Baltic Sea as demonstrated by e.g. the strong inter-annual variations in winter temperature and ice-coverage due to variations in dominating wind directions causing alternating mild and cold winters. The response of surface temperature and ice-coverage in the Baltic Sea to modest climate change may therefore be predicted using existing statistics. Due to the long response time in combination with complicated dynamics, the response of the salinity of the Baltic Sea cannot be predicted using existing statistics but has to be computed from mechanistic models. Salinity changes primarily through changes in the two major forcing factors: the supply of freshwater and the low-frequency sea level fluctuations in the Kattegat. The sensitivity of Baltic Sea salinity to changed freshwater supply is investigated using a simple mechanistic steady-state model that includes baroclinic geostrophic outflow from the Kattegat, the major dynamical factor controlling the freshwater content in the Kattegat and thereby the salinity of water flowing into the Baltic Sea. The computed sensitivity of Baltic Sea surface salinity to changes of freshwater supply is similar to earlier published estimates from time-dependent dynamical models with higher resolution. According to the model, the Baltic Sea would become fresh at a mean freshwater supply of about 60 000 m3 s-1, i.e. a 300% increase of the contemporary supply. If the freshwater supply in the different basins increased in proportion to the present-day supply, the Bothnian Bay would become fresh already at a freshwater supply of about 37 000 m3 s-1 and the Bothnian Sea at a supply of about 45 000 m3 s-1. The assumption of baroclinic geostrophic outflow from the Kattegat, crucial for the salinity response of the Baltic Sea to changed freshwater supply, is validated using daily salinity profiles for the period 1931-1977 from lightship Läsö Nord.

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