Seasonal variation of the cold intermediate water in the Southwest Black Sea and its interaction with the Sea of Marmara during the period of 1996–1998

Altıok H., Yüce H., ALPAR Ş. B.

MEDITERRANEAN MARINE SCIENCE, vol.1, no.2, pp.31-40, 2000 (SCI-Expanded)

  • Publication Type: Article / Article
  • Volume: 1 Issue: 2
  • Publication Date: 2000
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aquatic Science & Fisheries Abstracts (ASFA), BIOSIS, CAB Abstracts, Veterinary Science Database, Directory of Open Access Journals
  • Page Numbers: pp.31-40
  • Istanbul University Affiliated: Yes



Seasonal variation of the cold intermediate water (CIW) in the South Western Black Sea and its entrance into the Strait of Istanbul (Bosphorus, SOI) within the upper layer flow have been studied by using monthly oceanographic data sets collected in 1997-1998 period. In addition, the advection of the CIW via SOI to the Sea of Marmara (SOM) has been investigated.
The CIW is a permanent and characteristic water mass of the Black Sea, renewed every year by winter convection markedly observed in the North-western Black Sea. It is transported with the rim current along the boundary of the basin. The average temperature of the CIW is about 6oC. Its upper and lower boundaries are defined as 8 oC isotherms. The upper layer boundary rise up to the 20 m depth in the shelf and coastal upwelling regions with a thickness of 40 m. On the other hand, the depth of the upper layer boundary may decrease down to 40 m with a thickness of 120 m in the anticyclonic regions.
The CIW was observed in the vicinity of the SOI in the Black Sea exit region from April to September, located between 30 and 65m depth. However, the CIW, within the Black Sea’s upper layer flow, does not enter into the SOI in the beginning (April, May) and at the ending (September) of this period. In summer (June, July and August), the CIW was located between 20 and 50m depth was observed in the northern entrance of the SOI and it was carried into the SOI by the south bound surface current. Its temperature increases southwards along the SOI, due to the mixing with the warm surface water and warm bottom water, as well. This increment varies in the range of 2-4 oC depending on the rate of mixing. The physically altered waters enter into the SOM with temperature of 11-14 oC. 
In the SOM, a residual cold intermediate layer (CIL) was just placed on top of the halocline. This layer is evident in summer. The average temperature of the upper layer increases from spring to autumn. However in some months there is a decrement in the average temperature of the upper layer. This cooling may be caused by the altered waters of the CIW entering into the SOM. Further studies are needed to explain this event.