A. K. Ambrosimov

Comprehensive studies of the Caspian Sea system during cruise 35 of the R/V Rift

141 A interdisciplinary expedition was conducted aboard the R/V Rift (cruise 35; June 4–19, 2010) to study the system of the Caspian Sea. The hydrophysi cal, hydrochemical, sedimentological, and geological characteristics of the atmosphere, the water’s thick ness, and the bottom sediments were investigated. The works were performed in the Middle Caspian Sea and lengthwise the submeridional transect up to the South Basin of the Caspian Sea (Fig. 1).

An integrated study in the northern Caspian Sea: The 30th voyage of the R/V Rift

439 The 30th voyage of the R/V Rift was conducted on April 17–28, 2009. The main goal of the expedition was the comprehensive integrated exploration of the contemporary sedimentation system in the northern Caspian Sea in the mid spring season. The basic tasks involved measurements of the marine environmental features and the collection of relevant samples for the subsequent analysis and interpretation of the obtained data. Use was made of various techniques: CTD and ADCP profiling; the recording of currents with moor ing stations; optical observations with a Secci disk, a PUM transparency probe, a floating spectroradiome ter, and satellite data reception; hydrochemical deter minations of the О2, Si, and PO4; sedimentology (the aerosols, suspended matter, and pigments and the use of a Coulter counter); and marine biology (collecting samples of phyto and zooplankton). One of the main goals of the expedition was the lifting and mooring of subsurface buoy stations with sediment traps and “Potok” current meters. The route of the expedition and the stations’ positions are shown in Fig. 1.

On vertical particle fluxes in the Caspian Sea

The first results of studies of vertical fluxes of sediment particles using the sediment traps at the Trans-Caspian section are presented. The flux values and distribution regularities are established. The fluxes of particles forming the sediment are also determined. The intra-annual variability in the fluxes corresponds to the seasonal variability of the biological activity. Above the northern slope of the Derbent Basin, the maximum vertical fluxes are recorded in the winter, which is caused by the intensification of the near-bottom currents.

Spatiotemporal variability of the flow in the deep part of the Central Caspian Sea

The paper presents the analysis of hydrophysical observations executed along the Transcaspian section in 2004-2014 during the expeditions by Shirshov Institute of Oceanology of Russian Academy of Sciences. The results used in the paper are the generalization of data obtained in the last decade. Investigations of the current system of the Central Caspian Sea demonstrated that at the northeastern part of the cyclonic circulation there are considerable deviations. The deposits that energy of current disturbances of various spatiotemporal scales makes to the general energy of currents, are calculated. Preliminary results are received of the assessment of water transfer through the Apsheron threshold from the Central to the Southern Caspian Sea and vice versa. It is shown that annual recurrence of concentration of hydrogen sulfide in the benthonic hollows of the Caspian Sea is directly connected with seasonal and synoptic variability of currents at the bottom.

Water wave motions in the bottom layer of shallow water areas (on the example of the Vistula Lagoon in the Baltic Sea)

Synchronous instrumental measurements of the characteristics of bottom currents and surface waves in the shallow Vistula Lagoon in the Baltic Sea were carried out for the first time from May 15 to June 17, 2009. It is proved experimentally that the bottom gradient currents which can have the direction up to the opposite one to the wind impact, are formed in the enclosed and semi-enclosed water bodies. This is caused by the water surface denivellation formed in the case of the long impact of wind with the same direction. Bottom water oscillations induced by surface waves cause the bottom current velocity modulation and favor increase in the horizontal velocity component. The typical values of horizontal and vertical oscillations of bottom water are estimated for the most active storm during the measurement period that was registered on June 12, 2009 (the southwestern wind with the average speed up to 10.5 m/s, the mean wave height is 0.6–0.8 m).

Comprehensive study of the Caspian Sea system during the second cruise of the research vessel Nikifor Shurekov

311 A comprehensive expedition onboard the R/V Nikifor Shurekov was carried out from August 21 to September 9, 2013, within basic research program no. 23 of the Presidium of the Russian Academy of Sciences (project no. 10.1, Trans European Meridi onal Sea Ecological Geochemical Section) with the aim to study the sedimentation system of the Caspian Sea (Fig. 1a). The currents were measured with an ADCP WHS 150 current profiler (Teledyne RDI) through out the sea depth along the path of the vessel. The water depth was sounded 29 times with a multipara metric SBE 25 CTD profiler at complex stations (in 26 cases) along with an Idronaut Ocean 316 CTD profiler. The hydrochemical parameters (biogenic elements, O2, H2S) were measured onboard the ves sel and chlorophyll “a” (chl “a”) with a Trilogy fluo rometer (Turner Design), and the suspended partic ulate matter (SPM) concentration and size distribu tion, with vacuum filtering and a Coulter particle analyzer (Multisizer 3, Beckman Coulter Co.). The bottom sediments were sampled with an Ekman Bot tom corer 400 (KC Denmark). Three of five submerged buoy stations (SBS) with LOTOS 3 (Experimental Design Bureau of Oceano logical Engineering, Russian Academy of Sciences) and MSL 110 (Institute of Oceanology, Russian Academy of Sciences) sediment traps, POTOK 2M current meters (Experimental Design Bureau of Oceanological Engineering, Russian Academy of Sci ences), and an ADCP Argonaut MD profiler (Son tek) deployed during the 41st cruise of R/V Rift [1], were lifted up.

Seasonal characteristics of waves in the southeastern part of the Baltic Sea in 2008–2009

Presented are the characteristics of waves in the southeastern part of the Baltic Sea obtained from the results of continuous instrumental observations in 2008–2009 on the offshore oil-and-gas platform. Discussed are the conditions and prerequisites for the formation of extreme waves.

Geological research in the North Atlantic on cruise 51 of the R/V Akademik Ioffe

A. A. Klyuvitkina, *, N. V. Politovaa, A. N. Novigatskya, E. A. Novichkovaa, A. S. Savvichevb, N. V. Kozinaa, D. P. Starodymovaa, A. V. Tikhonovaa, A. K. Ambrosimova, D. F. Budkoa, S. M. Isachenkoc, and A. V. Bulokhova aShirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia bWinogradsky Institute of Microbiology, Federal Research Center Fundamentals of Biotechnology, Russian Academy of Sciences, Moscow, Russia cAtlantic Branch, Shirshov Institute of Oceanology, Russian Academy of Sciences, Kaliningrad, Russia

Experimental study of the relationship between the wave groupiness and wave height

It is demonstrated that the greatest influence of the variations in the groupiness of storm waves in the Baltic Sea concerns the highest waves. The variations in the height of less high waves are defined by wind speed. It is revealed that the height of 3% of the highest waves depends on their bandwidth: higher and lower waves are characterized by the larger and smaller set of frequencies, respectively. The significant wave height does not almost depend on the bandwidth. It is found that the spectrum of storm waves in the southwestern part of the Baltic Sea has a multi-peak structure which reflects the complex structure of waves consisting of several wave systems. Envelopes and individual waves of different frequency ranges superimpose, and extreme waves are generated. The probability of occurrence of extreme waves is maximum at the moments of the maximum development of wave groupiness.

Hydrochemical conditions of the “Chistaya Banka” polygon in the Volga’s avant delta

Characteristics of different types of river drainage were obtained during studies of a polygon in the near-mouth part of the Volga River in 2000–2003: “fast” (flowing through deep channels) and “slow” (that which passes through the littoral parts of the delta (1–2 m)). The low current velocities (lower than in the channel waters by a factor of ten), the abundance of water vegetation, and the strong heating of the waters lead to the high intensity of the biochemical processes. Therefore, the chemical composition of the waters is subjected to significant transformation with intensity so high that it allows comparing these regions with some sort of “bioreactor.” These changes influence the dissolved oxygen and various forms of carbon content.