Regions Of World Ocean Research Articles

ICE COVER OF THE EUROPEAN SECTOR OF THE ARCTIC AND SURFACE HEIGHTS OF THE ATLANTIC INNER SEAS (ON THE EXAMPLE OF THE BLACK SEA)

ICE COVER OF THE EUROPEAN SECTOR OF THE ARCTIC AND SURFACE HEIGHTS OF THE ATLANTIC INNER SEAS (ON THE EXAMPLE OF THE BLACK SEA)

A Relocatable Ocean Modeling Platform for Downscaling to Shelf-Coastal Areas to Support Disaster Risk Reduction

High-impact ocean weather events and climate extremes can have devastating effects on coastal zones and small islands. Marine Disaster Risk Reduction (DRR) is a systematic approach to such events, through which the risk of disaster can be identified, assessed and reduced. This can be done by improving ocean and atmosphere prediction models, data assimilation for better initial conditions and developing an efficient and sustainable impact forecasting methodology for Early Warnings Systems. A common user request during disaster remediation actions is for high-resolution information, which can be derived from easily deployable numerical models nested into operational larger-scale ocean models. The Structured and Unstructured Relocatable Ocean Model for Forecasting (SURF) enables users to rapidly deploy a nested high-resolution numerical model into larger-scale ocean forecasts. Rapidly downscaling the currents, sea level, temperature, and salinity fields is critical in supporting emergency responses to extreme events and natural hazards in the world’s oceans. The most important requirement in a relocatable model is to ensure that the interpolation of low-resolution ocean model fields (analyses and reanalyses) and atmospheric forcing is tested for different model domains. The provision of continuous ocean circulation forecasts through the Copernicus Marine Environment Monitoring Service (CMEMS) enables this testing. High-resolution SURF ocean circulation forecasts can be provided to specific application models such as oil spill fate and transport models, search and rescue trajectory models, and ship routing models requiring knowledge of meteo-oceanographic conditions. SURF was used to downscale CMEMS circulation analyses in four world ocean regions, and the high-resolution currents it can simulate for specific applications are examined. The SURF downscaled circulation fields show that the marine current resolutions affect the quality of the application models to be used for assessing disaster risks, particularly near coastal areas where the coastline geometry must be resolved through a numerical grid, and high-frequency coastal currents must be accurately simulated.

Studying randomness and determinism in surface temperature anomaly indices using the recurrence plot method

Surface temperature anomalies are studied using the methods of recurrence plots and statistical R/S analysis, as well as the Higuchi method for determining fractal dimension. Anomalies of the surface temperature above continents and the temperature in the World Ocean regions and in the Northern and Southern hemispheres are considered independently. It has been indicated that anomalies are more stochastic and deterministic for land and ocean surfaces, respectively.

Жирнокислотный состав Alteromonas-подобных бактерий Черного моря

Alteromonas macleodii strains isolated from the Black sea water were similar in their fatty acids composition with the type strain of this species. Analysis of lipid composition of 10 A. macleodii strains isolated from the deep and surface water layers in different World ocean regions including the Black sea water has shown that the deep and surface isolates of this species formed two groups different in their fatty acids profiles. The Black sea isolates of Pseudoalteromonas haloplanktis, P. citrea, P. flavipulchra conformed to these species type strains in their fatty acids composition. On the basis of the fatty acids spectra similarity of three Pseudoalteromonas species strains with Plipolytica described in 2010 has been established. Presence of three isomers C16:1ψ7, C 16:1ψ9 and C16:1ψ6--components of hexadecenic acid in the Black sea isolates of Shewanella baltica has been shown.

Features of the behavior of vertically distributed hydroacoustic receiving systems in the presence of drowned flows

The features of the behavior of vertically distributed extended receiving systems (VDRSs) are considered as applied to low-frequency ocean tomography. The most widespread form of such systems is a structure that consists of a conductor-and-support cable of several hundred meters, on which receiving modules are mounted, as well as a buoy and an anchor to ensure the spatial position of the system. The results of experiments performed using VDRSs with lengths of 32 and 128 m in a water area of the White Sea are discussed. The influence of drowned flows on such a VDRS leads to a time dependence of its spatial position with respect to the vertical line passing through the anchor system. In addition, vibrations of system’s elements, especially the conductor-and-support cable, are generated, transferred to hydrophones, and lead to the formation of a pseudoacoustic signal, which, under certain conditions, can substantially exceed the background noise level in the water area. These circumstances considerably reduce the efficiency of VDRSs and limit the measurement frequency range from below. Analysis of the experimental data obtained with this type of receiving system in different World Ocean regions at different depths and under different hydrological conditions reveals a certain similarity in the character of pseudoacoustic signals recorded with VDRSs. The similarity of the results of various experiments points to the existence of a common mechanism of vibration generation and pseudosound induction. Determining this mechanism may reveal how to eliminate these undesirable phenomena and extend the VDRS frequency range toward the infrasonic.

Estimates of the aerosol radiative forcing for three regions of World Ocean

We present the results of numerical simulation of aerosol radiative forcing for three regions of the World Ocean: the coastal zone of Antarctica, the Sea of Japan, and the Sea of Darkness. The aerosol radiative forcing for separate regions of ocean was simulated using ship-based measurements of aerosol optical depth and atmospheric water vapor content. Data on the single scattering albedo and asymmetry factor of scattering phase function are presented according to model simulations (coastal zone of Antarctica: OPAC model) and multiyear observations at AERONET photometer stations (the Sea of Japan: Noto site; and the Sea of Darkness: Cape Verde site). The calculations showed that the cooling effect of aerosol over Sea of Japan/Sea of Darkness at the atmospheric boundaries increases by about an order of magnitude as compared to the clean atmosphere near Antarctica. At the same time, the daily average values of the aerosol radiative forcing vary as follows: from −2.3 (Antarctica) to −30.3/−32.6 W/m2 (Sea of Japan/Sea of Darkness) at the surface level and from −1.9 to −16.1/−18 W/m2 at the top of the atmosphere. The estimates obtained agree reasonably well with the results of other authors.

The SST Multidecadal Variability in the Atlantic–Mediterranean Region and Its Relation to AMO

Abstract Two sea surface temperature (SST) time series, the Extended Reconstructed SST version 3 (ERSST.v3) and the Hadley Centre Sea Ice and Sea Surface Temperature dataset (HadISST), are used to investigate SST multidecadal variability in the Mediterranean Sea and to explore possible connections with other regions of the global ocean. The consistency between these two time series and the original International Comprehensive Ocean–Atmosphere Dataset version 2.5 (ICOADS 2.5) over the Mediterranean Sea is investigated, evaluating differences from monthly to multidecadal scales. From annual to longer time scales, the two time series consistently describe the same trends and multidecadal oscillations and agree with Mediterranean ICOADS SSTs. At monthly time scales the two time series are less consistent with each other because of the evident annual cycle that characterizes their difference. The subsequent analysis of the Mediterranean annual SST time series, based on lagged-correlation analysis, multitaper method (MTM), and singular spectral analysis (SSA), revealed the presence of a significant oscillation with a period of about 70 yr, very close to that of the Atlantic multidecadal oscillation (AMO). An extension of the analysis to other World Ocean regions confirmed that the predominance of this multidecadal signal with respect to longer period trends is a unique feature of the Mediterranean and North Atlantic Ocean, where it reaches its maximum at subpolar latitudes. Signatures of multidecadal oscillations are also found in the global SST time series after removing centennial and longer-term components. The analysis also reveals that Mediterranean SST and North Atlantic indices are significantly correlated and coherent for periods longer than about 40 yr. For time scales in the range 40–55 yr the coherence between the Mediterranean and subpolar gyre temperatures is higher than the coherence between the Mediterranean SST and North Atlantic Oscillation (NAO) or AMO. Finally, the results of the analysis are discussed in the light of possible climate mechanisms that can couple the Mediterranean Sea with the North Atlantic and the Global Ocean.

Mixing by low‐ and high‐resolution surface geostrophic currents

The nature of mixing near the ocean's surface is investigated by considering passive tracer advection by currents derived geostrophically using sea surface height fields that differ in their spatiotemporal resolution. One is a low‐resolution field that can be thought of as being derived using current‐generation groundtrack altimetric measurements. The other is a high‐resolution field that may be envisioned as derived using hypothetical next‐generation wideswath altimetric measurements. The investigation is carried out in two world ocean regions with quite distinct characteristics and which have been the focus of recent studies on mixing by altimetry‐derived currents. One region corresponds to an ample domain in the South Atlantic, which is traversed by vortices shed from the Agulhas current. The other region corresponds to a portion of the Pacific sector of the Southern Ocean, which is dominated by multiple zonal jets associated with the Antarctic Circumpolar Current. It is argued that while altimetry‐derived currents capture the most salient characteristics of surface ocean mixing, deterministic Lagrangian calculations may be improved by considering surface geostrophic currents with greater spatiotemporal resolution. This is supported on analysis of probability distribution functions of finite‐time Lyapunov exponents (FTLEs); inspection of Lagrangian coherent structures (or LCSs), which constitute distinguished material fluid curves that organize mixing; computation of kinetic energy and FTLE variance spectra; and realization of explicit passive tracer advection experiments.

Experimental Study into the UHF-Wave Attenuation Factor in the World Ocean Regions

Experimental Study into the UHF-Wave Attenuation Factor in the World Ocean Regions