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.     

Human–environment interaction in the Baltic Sea

A model based on a Bayesian Belief Network (BBN) has been constructed for the Baltic Sea with the aim of investigating future scenarios of human activities in the region and informing environmental management strategies, such as those developed under a Science and Policy Integration for Coastal Zone Assessment Systems Approach Framework application. This paper describes necessary refinements to take into account historical influences on this relatively enclosed system. BBNs are static models and therefore do not incorporate feedback loops, whereas natural systems clearly display feedback mechanisms. This paper describes the implementation of one step feedback loops into a BBN model in an attempt to partly remove this constraint. Feedback loops within this stochastic model were shown to improve its accuracy. The drivers, both natural and anthropogenic, having greatest impact on the environment are identified. These refinements were made to improve its accuracy in modelling the system and gives insights into the functioning of that system.     

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.     

Phytoplankton community in the Western Arctic in July–August 2003

The phytoplankton community was studied in Bering Strait and over the shelf, continental slope, and deep-water zones of the Chukchi and Beaufort seas in the middle of the vegetative season (July–August 2003). Its structure was analyzed in relation to ice conditions and the seasonal patterns of water warming, stratification, and nutrient concentrations. The overall ranges of variation in phytoplankton abundance and biomass were estimated at 2.0 × 10² to 6.0 × 10⁶ cells/l and 0.1 to 444.1 mg C/m³. The bulk of phytoplankton cells concentrated in the seasonal picnocline, at depths of 10–25 m. The highest values of cell density and biomass were recorded in regions influenced by the inflow of Bering Sea waters or characterized by intense hydrodynamics, such as the Bering Strait, Barrow Canyon, and the outer shelf and slope of the Chukchi Sea. In the middle of the vegetative season, the phytoplankton in the study region of the Western Arctic proved to comprise three successional (seasonal) assemblages, namely, the early spring, late spring, and summer assemblages. Their spatial distribution was dependent mainly on local features of hydrological and nutrient regimes rather than on general latitudinal trends of seasonal succession characteristic of arctic ecosystems.     

On the Mechanism of Decadal Oscillations in the Ocean–Atmosphere System

The aim of the work is to check the hypothesis that quasiperiodic oscillations of meridional heat transport intensified by a positive feedback existing in the ocean–atmosphere system in subtropical regions is one of the principal factors governing the decadal variability of various hydrophysical fields in the North Atlantic. We use a simple three-box model of the North Atlantic with one lower and two upper boxes and meridional circulation for typical parameters of the ocean–atmosphere system. It is assumed that the decadal anomalies of sea-level pressure are proportional to the anomalies of sea-surface temperature. The deduced system of ordinary differential equations for the temperature of the upper two boxes with quadratic nonlinearity and the behavior of the solution in the vicinity of the stationary point are analyzed by using standard procedures for the investigation of linearized equations for small perturbations. It is shown that, for typical parameters of the ocean–atmosphere system, oscillating solutions for the sea-surface temperature with periods of 10–20yr can be realized even without taking salinity into account.     

Dynamic Processes of the Arctic Stratosphere in the 2020–2021 Winter

Izvestiya, Atmospheric and Oceanic Physics - The Arctic stratosphere winter season of 2020–2021 was characterized by a weakened stratospheric polar vortex as a result of a major sudden...     

Russian Investigations in the Field of Atmospheric Radiation in 2015–2018

Izvestiya, Atmospheric and Oceanic Physics - A short survey prepared by the Russian Commission on Atmospheric Radiation contains the most significant results of works in the field of...     

Some directions in the development of dynamic meteorology in Russia in 2007–2010

A brief review of the results of investigations carried out by Russian scientists in the field of dynamic meteorology in 2007–2010 is presented. This review is based on the information prepared by the Commission on the Dynamic Meteorology of the National Geophysical Committee, Russian Academy of Sciences, and included in the general information report of the Section of Meteorology and Atmospheric Sciences at the XXV General Assembly of the International Union of Geodesy and Geophysics.     

Russian investigations in the field of atmospheric radiation in 2007–2010

A short survey prepared by the Russian Commission on Atmospheric Radiation contains the most significant results of works in the field of atmospheric-radiation studies performed in 2007–2010. It is part of the Russian National Report on Meteorology and Atmospheric Sciences prepared for the International Association on Meteorology and Atmospheric Sciences (IAMAS). During this period, the Russian Commission on Atmospheric Radiation, jointly with concerned departments and organizations, ran the conference “Physics and Education,” dedicated to the 75th anniversary of the Department of Physics at St. Petersburg State University (2007); the International Symposium of CIS Countries “Atmospheric Radiation and Dynamics” (2009); and the 5th International Conference “Atmospheric Physics, Climate, and Environment” (2010). At the conferences, central problems in modern atmosphere physics were discussed: radiative transfer and atmospheric optics; greenhouse gases, clouds, and aerosols; remote methods of measurements; and new measurement data. This survey presents five directions covering the whole spectrum of investigations performed in the field of atmospheric radiation.     

Hydrological characteristics in the Tunisia–Sardinia–Sicily area during spring 1995

Within the framework of the Tunisian – EC SALTO/AVICENNE project, four hydrological sections were performed between Tunisia, Sardinia and Sicily with a 10–20 km sampling interval in April–June 1995. To our knowledge, it is the first time that sections were repeated there at such a high frequency. These data significantly increase the number of observations available on the Tunisian side of the Channels of Sardinia and Sicily, and allow reliable specification of the hydrological characteristics of the area. For the first time, and as confirmed by infrared satellite images, these data sets show (i) the large mesoscale variability of the surface flow entering the study area, as expected from the characteristics of the Algerian Current upstream, (ii) the rapid changes it undergoes around northeastern Tunisia, as it shifts roughly from southward to eastward within less than a few weeks. These data also show a large heterogeneity at intermediate levels, clearly associated with waters of very different origins that follow converging routes and mix in both the study area and the southern Tyrrhenian Sea. They finally document the fundamental importance of bathymetric features of relatively small scale such as the Skerki passage.     

Ice extent in the Greenland Sea 1978–1995

During the European Subpolar Ocean Programme (ESOP) project from 1993 to 1995, very little ice was formed in the central Greenland Sea. The large-scale ice cover in the area during the period October 1978 to June 1995 has been mapped using passive microwave data from the scanning multichannel microwave radiometer (SMMR) and the special sensor microwave/imager (SSM/I). Special emphasis is put on the last three years of the period (the ESOP years), from the summer of 1992 to the summer of 1995. The results for the three winters compared with the average winter of the previous 12 yr show unusually little ice in the Greenland Sea during the winters of 1993–1995. In particular, the winters of 1994 and 1995 saw no ice (i.e. no Odden) in the central Greenland Sea at all. Another result is an observed upper limit of approximately 250,000 km² to the seasonal ice cover in the study region (the Odden Area) within the central Greenland Sea over the period 1978–1995.     

Variability of the Bering Sea circulation in the period 1992–2010

Sea surface height anomalies observed by satellites in 1992–2010 are combined with monthly climatologies of temperature and salinity to estimate circulation in the southern Bering Sea. The estimated surface and deep currents are consistent with independent velocity observations by surface drifters and Argo floats parked at 1,000?m. Analysis reveals 1–3-Sv interannual transport variations of the major currents with typical intra-annual variability of 3–7?Sv. On the seasonal scale, the Alaskan Stream transport is well correlated with the Kamchatka (0.81), Near Strait (0.53) and the Bering Slope (0.37) currents. Lagged correlations reveal a gradual increase of the time the lags between the transports of the Alaskan Stream, the Bering Slope Current and the Kamchatka Current, supporting the concept that the Bering Sea basin is ventilated by the waters carried by the Alaskan Stream south of the Aleutian Arc and by the flow through the Near Strait. Correlations of the Bering Sea currents with the Bering Strait transport are dominated by the seasonal cycle. On the interannual time scale, significant negative correlations are diagnosed between the Near Strait transport and the Bering Slope and Alaskan Stream currents. Substantial correlations are also diagnosed between the eddy kinetic energy and Pacific Decadal Oscillation.     

Some aspects in the development of dynamic meteorology in Russia in 2003–2006

A brief review of the studies performed by Russian scientists in dynamic meteorology in 2003–2006 is presented. This review is based on the material prepared by the Commission on Dynamic Meteorology of the National Geophysical Committee of the Russian Academy of Sciences and included in the general information report of the Section of Meteorology and Atmospheric Sciences at the 24th General Assembly of the International Union of Geodesy and Geophysics.     

Russian investigations in the field of atmospheric radiation in 2011–2014

A short survey prepared by the Russian Commission on Atmospheric Radiation contains the most significant results of work in the field of atmospheric-radiation studies performed in 2011–2014. It is part of the Russian National Report on Meteorology and Atmospheric Sciences prepared for the International Association on Meteorology and Atmospheric Sciences (IAMAS)¹. During this period, the Russian Commission on Atmospheric Radiation, jointly with the concerned departments and organizations, organized two International Symposiums on Radiation and Dynamics (ISARD-2011 and ISARD-2013). At these conferences, the central problems in modern atmospheric physics were discussed: radiative transfer (RT) and atmospheric optics; greenhouse gases, clouds, and aerosols; remote methods of measurements; and new measurement data. This survey presents six directions covering the whole spectrum of investigations performed in the field of atmospheric radiation.     

Alternatives to ITQs in equity–efficiency–effectiveness trade-offs: How the lay-up system spread effort in the BC halibut fishery

Individual Transferable Quotas (ITQs), also called “catch shares”, have been broadly adopted in the last two decades, at the same time that concerns about their equity and effectiveness in delivering the predicted outcomes have increased. This paper documents how an alternative fishermen-designed and operated system of spreading fishing effort to avoid the race for fish—called the lay-up system—worked effectively and equitably for four decades in the British Columbia halibut fishery before ITQs were introduced in this fishery. Why the lay-up system was allowed to collapse and its history ignored illustrates important roles played by conflicting ideologies, bureaucratic rationality, and the inability to imagine an alternative way of solving fisheries management problems. Trade-offs between the efficiency, equity, and effectiveness of halibut and other management systems are considered.     

Variations in the Atlantic inflow to the Nordic Seas, 1955–1996

Hydrographic observations on the Svinøy section, which runs NW from about 62°N on the Norwegian coast to 64°40′N on the prime meridian, have been used to investigate variations in the Atlantic inflow to the Nordic Seas. The data are from the winter 1955 to 1973 and from the spring and the summer 1978 to 1996. The observations show that in the summer there exist two cores of water with salinity above 35.25 at about 100 m depth, but in the spring and the winter the core furthest offshore is less distinct. Geostrophic calculations show that, for all data sets, there are two kernels with northward currents in the Svinøy section: one over the inner part of the continental slope (over 600–800 m depths) and one further offshore (over 1400–2500 m depth). The mean volume transports of Atlantic water in the section are 4.5, 5.0 and 5.6 Sv in spring, summer and winter, respectively. Results from an Empirical Orthogonal Function analysis of the summer data indicate that there is a dual structure in the section when interannual variations are considered. In the western part of the section the temperature and salinity are negatively correlated with the winter North Atlantic Oscillation index, but in the eastern part of the section they are weakly positively correlated. This is not found in the winter data from 1955 to 1973. The geostrophic volume transport in the summer through the Svinøy section is positively correlated with the NAO indices for winter and spring, where the March NAO index gave the best correlation. Also, the summer volume transports west and east in the section seem to be in opposite phase. From the summer data 1978 to 1996 there is a positive linear trend for the eastern transport (+2.4 Sv), but there is a negative linear trend for the western transport (−2.0 Sv). The transport through the whole section has increased by 1.1 Sv during the same similar period. The atmospheric conditions were different in years with relatively low temperatures and salinities in the western part of the section compared to those years with relatively high temperatures and salinities. It is proposed that interannual variations of temperature, salinity and volume transport in the Svinøy section are controlled mostly by a large-scale variable pressure system (i.e. the North Atlantic Oscillation index).     

Sediment Transport Capacity Under the River–Tide Interaction in the Changjiang Estuary

Sediment transport capacity is a fundamental parameter in sediment transport theory and its accurate calculation is important from both theoretical and engineering viewpoints. The capacity of sediment transport has been studied extensively by many researchers in the last decades. Nevertheless, the underlying mechanism behind sediment transport capacity in estuaries remains poorly understood. The current study aims to explore the impact of the river–tide interaction on sediment transport and establish a formula of sediment transport capacity under the river–tide interaction. The impact of the river–tide interaction on the hydrodynamics and sediment dynamics in the Changjiang Estuary was analyzed, a practical method for describing the variation in tide-runoff ratio was established,and a formula of sediment transport capacity considering the impact of river–tide interaction was proposed by introducing the tide-runoff ratio. The new method bridged the gap between two well-known sediment transport capacity methods by considering the variation in the index a for the gravitational term and overcomes the drawback of distinguishing flood/dry season or spring/ebb tide in the calculation of estuarine sediment transport. A large amount of flow and sediment data obtained from the Changjiang Estuary were collected to verify the proposed formula. The effect of salt-fresh water mixture and the morphological evolution on sediment transport capacity of the Changjiang Estuary were discussed.     

Interannual variations of the planktonic ecosystem in the slope water and Kuroshio south of Japan in February in the years 1990–2002

To determine recent interannual variations in the planktonic ecosystem of the slope water south of Japan, an area between 1000 m isobath on the continental slope and assumable Kuroshio front, in reference to preceding reports on the Kuroshio, we examined interannual variations of physical factors, sea surface chlorophyll concentration (SSChl), size-fractioned copepod biomass and the abundance of Calanus sinicus, one of the dominant copepods in the region, in February from 1990 to 2002. In the slope water, SSChl concentration had generally shown a higher value than in the Kuroshio and increase of the SSChl in both areas started in February but lasted longer in the slope water. The regional distribution of copepod biomass and C. sinicus abundance was similar to that of phytoplankton in that they were distributed more densely in the slope water than in the Kuroshio, reflecting assumed higher nutrient supply. The interannual variation in sea surface temperature in the slope water was explained by the rise of air temperature in 1998, a strong El Niño year, and subsequent change in the Kuroshio path (1999–2001). The interannual variation of the planktonic community, i.e. sea surface chlorophyll concentration and copepod biomass, was attributed to the effects of those physical events through the direct effect of local temperature and/or variation in surface irradiance, except for a prominent increase of copepods in the slope water in 2000. The effect of interannual change in the vertical mixing, suggested in previous studies, was not apparent in February, when the primary production is not limited by nutrient concentration which would be more important in regulating biological production in later months.     

Water Structure and Kinematics in the Region of the Argentine Islands Archipelago in March–April 2000

On the basis of the data of a comprehensive oceanographic experiment carried out in the course of the fifth national expedition to Antarctica in March–April 2000, we study the structure and kinematics of waters in the region of the Argentine Islands, where the Akademik Vernadskii Ukrainian Antarctic Station is located. We study the regularities of the thermohaline stratification of waters, the characteristics of the field of dissolved oxygen, and the distribution of the light attenuation coefficient. The data on tidal and residual currents are also presented.