Assessment of the influence of material glaciation in the Northern Hemisphere on the processes of water desalination in the Mediterranean Sea in the Pliocene-Pleistocene

The article calculates the freshwater balance of the ancient Black and Caspian seas and estimates the volume of water flowing from the Black Sea to the Mediterranean during the melting of glaciers. It is shown that during this period up to 855 km3/year of freshwater is discharged into the Mediterranean Sea, which is involved in the formation of sea level. A comparison of calculations and geological data showed that there are no signs of the influx of salty ocean water into the Akchagyl Sea. It was also shown that water from the ocean cannot flow up since the sea level was below sea level.

Geographical distribution and volume of Antarctic icebergs derived from ship observation data

ABSTRACTInformation on the occurrence, spatial distribution and morphometric characteristics of Antarctic icebergs is needed in a large number of applications including navigation, heat and freshwater balance calculations, biochemistry of the ocean and climatology. Using over 60 000 ship observations of icebergs in the Southern Ocean collected since the end of the 1940s we have produced a detailed map of the distribution of Antarctic icebergs as well as maps of related statistics including the standard deviation, minimum and maximum values of the iceberg concentration and the probability of iceberg-free observations. The study incorporated small and medium-sized icebergs with a length of <10 nautical miles. Most observations were taken during the warm period of the year, from December to April. It is shown that the iceberg distribution across the Southern Ocean is determined by the location of calving regions and peculiarities of the atmospheric circulation and ocean currents. Iceberg concentration data combined with information on the iceberg size and shape distribution have been used to evaluate the area-integrated characteristics of Antarctic icebergs. The instantaneous number of icebergs in the Southern Ocean was estimated as 132 269 with an uncertainty of 7%. The area and volume of icebergs were equal correspondingly to 55 805 km2 and 16 893 km3 with uncertainties of 32–33%.

Global-Scale Energy and Freshwater Balance in Glacial Climate: A Comparison of Three PMIP2 LGM Simulations

Three coupled atmosphere–ocean general circulation model (AOGCM) simulations of the Last Glacial Maximum (LGM: about 21 000 yr before present), conducted under the protocol of the second phase of the Paleoclimate Modelling Intercomparison Project (PMIP2), have been analyzed from a viewpoint of large-scale energy and freshwater balance. Atmospheric latent heat (LH) transport decreases at most latitudes due to reduced water vapor content in the lower troposphere, and dry static energy (DSE) transport in northern midlatitudes increases and changes the intensity contrast between the Pacific and Atlantic regions due to enhanced stationary waves over the North American ice sheets. In low latitudes, even with an intensified Hadley circulation in the Northern Hemisphere (NH), reduced DSE transport by the mean zonal circulation as well as a reduced equatorward LH transport is observed. The oceanic heat transport at NH midlatitudes increases owing to intensified subpolar gyres, and the Atlantic heat transport at low latitudes increases in all models whether or not meridional overturning circulation (MOC) intensifies. As a result, total poleward energy transport at the LGM increases in NH mid- and low latitudes in all models. Oceanic freshwater transport decreases, compensating for the response of the atmospheric water vapor transport. These responses in the atmosphere and ocean make the northern North Atlantic Ocean cold and relatively fresh, and the Southern Ocean relatively warm and saline. This is a common and robust feature in all models. The resultant ocean densities and ocean MOC response, however, show model dependency.

Simulated Variability of the Arctic Ocean Freshwater Balance 1948–2001

The Arctic Ocean freshwater balance over the period 1948–2001 is examined using results from a hindcast simulation with an ocean–sea ice model of the Atlantic and Arctic Oceans. Atmospheric forcing is taken from the NCEP–NCAR reanalysis and different terrestrial freshwater sources as well as the Bering Strait throughflow are specified as constant seasonal cycles. The long-term variability of the Arctic Ocean liquid freshwater content is determined by the variability of lateral exchanges with the subpolar seas. Surface freshwater flux variability is dominated by the thermodynamic growth of sea ice. This component of the freshwater balance has larger variability at interannual frequencies. The Arctic Ocean liquid freshwater content was at a maximum in the middle of the 1960s. Extremely low liquid freshwater export through Fram Strait caused this maximum in the freshwater content. The low export rate was related to weak volume transports in the East Greenland Current. Low volume transports were forced by a reduction in sea surface height across Fram Strait, triggered by anomalous meltwater from Barents Sea ice export that was carried toward Fram Strait with the West Spitzbergen Current. After the 1960s maximum liquid freshwater content, the Arctic Ocean gradually returned to an equilibrium between export through the passages toward the Atlantic and the freshwater sources.