The Structure and Long-Term Variability of the Bottom Layer in the Irminger Sea

This paper shows the important role that circulation can play in the long-term variability of thermohaline properties of the bottom layer in the Irminger Sea, and the increase in salinity in the 21st century in spite of intense ice melting in the Arctic and freshening of the upper and intermediate layers that started over the last 5–7 years in the North Atlantic.     

Structure and Variability of the Meridional Overturning Circulation in the North Atlantic Subpolar Gyre, 2007–2017

Doklady Earth Sciences - The vertical structure and interannual and long-term variability of the meridional overturning circulation in the North Atlantic Subpolar Gyre is analyzed. A close...     

Metal Concentrations in the Ecosystem and Around Recreational and Fish-Breeding Pond Bugach

Data of two field studies were used to analyze the concentrations of Na, K, Ca, Mg, Fe, Mn, Zn, Cu, Al, Cr, Ni, Cd, and Pb in the water, bottom deposits, zoobenthos, fish, and macrophytes of the Pond Bugach and in the soils near the pond. It was established that the majority of metals in the soils and bottom deposits correlate and their concentrations are governed by the universal geochemical factors of the region. The heavy metals were recognized that originate from anthropogenic sources and their concentrations were found to exceed the maximum admissible values for different components of the ecosystem. Five types of heavy metals migration were recognized in the soil–bottom deposits–zoobenthos–fish chain and in macrophytes. Statistically significant difference was found to exist between the concentrations of some heavy metals in the muscles of fish species with different food types (crucian carp and perch) as well as between the correlations of metals. The recorded concentrations were compared with the concentrations of metals measured in the last decade in other limnetic ecosystems in Siberia, Europe, North America, and China.     

Erratum to: The Khuvsgul Earthquake of January 12, 2021 (MW = 6.7, ML = 6.9) and Early Aftershocks

Izvestiya, Physics of the Solid Earth - An Erratum to this paper has been published: https://doi.org/10.1134/S1069351322100019     

Currents in the Drake Passage by the observations in October–November of 2011

The currents in the Drake Passage are studied from the ADCP and CTD data acquired in a section across the Drake Passage in October-November of 2011 and from the satellite altimeter data. A complicated pattern of currents including eight jets of the Antarctic Circumpolar Current (ACC) and a system of slope and abyssal currents was found. The most interesting result is the discovery of several cyclonic and anticyclonic mesoscale eddies confined to the abyss. Some reasons explaining the generation of such eddies by the meandering of the ACC jets in the upper ocean layer are presented.     

Heat budget of the surface mixed layer south of Africa

ARGO hydrographic profiles, two hydrographic transects and satellite measurements of air–sea exchange parameters were used to characterize the properties and seasonal heat budget variations of the Surface Mixed Layer (SML) south of Africa. The analysis distinguishes the Subtropical domain (STZ) and the Subantarctic Zone (SAZ), Polar Frontal Zone (PFZ) and Antarctic Zone (AZ) of the Antarctic Circumpolar Current. While no Subantarctic Mode Water forms in that region, occurrences of deep SML (up to ∼450 m) are observed in the SAZ in anticyclones detached from the Agulhas Current retroflection or Agulhas Return Current. These are present latitudinally throughout the SAZ, but preferentially at longitudes 10–20° E where, according to previous results, the Subtropical Front is interrupted. Likely owing to this exchange window and to transfers at the Subantarctic Front also enhanced by the anticyclones, the SAZ shows a wide range of properties largely encroaching upon those of the neighbouring domains. Heat budget computations in each zone reveal significant meridional changes of regime. While air–sea heat fluxes dictate the heat budget seasonal variability everywhere, heat is mostly brought through lateral geostrophic advection by the Agulhas Current in the STZ, through lateral diffusion in the SAZ and through air–sea fluxes in the PFZ and AZ. The cooling contributions are by Ekman advection everywhere, lateral diffusion in the STZ (also favoured by the ∼10° breach in the Subtropical Front) and geostrophic advection in the SAZ. The latter likely reflects an eastward draining of water warmed through mixing of the subtropical eddies.     

Winter convection in the Irminger Sea in 2004–2014

Winter convection in the Irminger Sea leading to the formation of Labrador Sea Water (LSW) is analyzed using CTD data collected along the 59.5° N transatlantic section in 2004–2014, winter Argo data from 2012–2014, and daily North American regional reanalysis (NARR). The interannual variability of LSW in the Irminger Sea is investigated. The dissolved oxygen saturation rate of 93% is used to indicate maximal local convection depth. It is shown that the deepest convection (up to 1000 m) resulting in the largest LSW volume that formed in the Irminger Sea in 2008 and 2012. These years were characterized by numerous storms with anomalously strong turbulent heat loss from the ocean to the atmosphere and negative air temperature to the east of the southern tip of Greenland in January–March. LSW became warmer by 0.42°C, saltier by more than 0.03 PSU, and more oxygenated by 8 µmol/kg between 2004 and 2014. A strong LSW decay in the Iceland Basin is also noted.     

Hydrodynamics of the Bottom-Water Flow from the Arctic to the Atlantic through the Strait of Denmark

Izvestiya, Atmospheric and Oceanic Physics - The overflow of bottom waters through the Strait of Denmark to the Atlantic has been investigated. A unique physical and hydrodynamic effect of...     

Deep currents in the central part of the Drake Passage based on the data of the 2008 hydrographic survey

The currents within the junction of the Shackleton and West-Scotia ridges in the central part of the Drake Passage are studied using the data of the hydrographic survey carried out in October–November of 2008. The absolute geostrophic currents were computed by matching the CTD and LADCP data. As a result, the complicated system of deep currents conditioned by the ocean bottom’s topography was revealed and described. A new path of propagation of the Antarctic Bottom Water has been revealed.