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The Mediterranean Sea, strategically situated across a dynamic frontier line that separates two regions with different climates (Europe and North Africa), has been the focus of attention of many studies dealing with its thermohaline circulation, deep water formation processes or heat and freshwater budgets. Large-scale atmospheric forcing has been found to play an important role in these topics and attention has been renewed in climatic indices that can be used as a proxy for atmospheric variability. Among them, the North Atlantic oscillation, the East Atlantic or the East Atlantic–West Russia patterns have been widely addressed but much less attention has been devoted to a Mediterranean mode, the Mediterranean oscillation. This overview summarizes the recent advances that have been achieved in the understanding of these climatic indices and their influence on the functioning of the Mediterranean from a physical point of view. The important role of the Mediterranean oscillation is emphasized and the most relevant aspects of the other indices are revisited and discussed. [ABSTRACT FROM AUTHOR]

In this paper we present new data from ship-based measurements and two-year observations from moorings in the Laptev Sea along with Russian historical data. The observations from the Laptev Sea in 2007 indicate that the bottom water temperatures on the mid-shelf increased by more than 3°C compared to the long-term mean as a consequence of the unusually high summertime surface water temperatures. Such a distinct increase in near-bottom temperatures has not been observed before. Remnants of the relatively warm bottom water occupied the mid-shelf from September 2007 until April 2008. Strong polynya activity during March to May 2007 caused more summertime open water and therefore warmer sea surface temperatures in the Laptev Sea. During the ice-free period in August and September 2007, the prevailing cyclonic atmospheric circulation deflected the freshwater plume of the River Lena to the east, which increased the salinity on the mid-shelf north of the Lena Delta. The resulting weaker density stratification allowed more vertical mixing of the water column during storms in late September and early October, leading to the observed warming of the near-bottom layer in the still ice-free Laptev Sea. In summer and autumn 2008, when the density stratification was stronger and sea surface temperatures were close to the long-term mean, no near-bottom water warming was observed. Warmer water temperatures near the seabed may also impact the stability of the shelf's submarine permafrost. [ABSTRACT FROM AUTHOR]

Considerable interannual differences were observed in river water and sea-ice meltwater inventory values derived from δ18O and salinity data in the Eurasian Basin along the continental margin of the Laptev Sea in the summers of 1993 and 1995, and in the summers of 2005 and 2006 during Nansen and Amundsen Basins Observational system (NABOS) expeditions. The annually different pattern in river and sea-ice meltwater inventories remain closely linked for all of the years studied, which indicates that source regions and transport mechanisms for both river water and sea-ice formation are largely similar over the relatively shallow Laptev Sea Shelf. A simple Ekman trajectory model for surface Lagrangian particles based solely on wind forcing can explain the main features observed between years with significantly different wind patterns and vorticities, and can also explain differences in river water distributions observed for years with a generally similar offshore wind setting. An index based on this simplified trajectory model is rather similar to the vorticity index, but reflects the hydrology on the shelf better for distinctive years. This index is not correlated with the Arctic Oscillation, but rather with a local mode of oscillation, which controls the outflow and distribution of the Eurasian Basin major freshwater source on an annual timescale. [ABSTRACT FROM AUTHOR]