Quasi-biennial variations in ozone and meteorological parameters over western Europe from ozonesonde data

Quasi-biennial variations in vertical profiles of ozone, temperature, air pressure, and zonal and meridional wind velocities are analyzed from ozonesonde data obtained at the western European stations of Lindenberg, Hohenpeissenberg, and Payerne. The effect of quasi-biennial variations manifests itself variously in different variables and is nonuniform in altitude. The period of quasi-biennial variations is not constant, and the values of the mean period group mainly around 2 and 2.5 years. As in the North American region, the effects of quasi-biennial variations in different parameters of the stratosphere and troposphere over western Europe are due to a combination of the effects of the quasi-biennial oscillation (QBO) in the equatorial stratosphere, the El Niño-Southern Oscillation (ENSO), and the North Atlantic Oscillation (NAO). The observed 2.5-year variations in stratospheric ozone are related to the equatorial QBO to a larger extent in comparison with variations in other variables. It seems likely that a determining influence on variations in stratospheric wind and temperature is exerted by the ENSO. Variations in tropospheric and stratospheric parameters with a mean period of about 2 years are due to the ENSO and NAO effects.     

Suspended barite as a tracer of biological activity in the Southern Ocean

During two cruises in the Southern Ocean (INDIGO 3, Indian sector and EPOS 2, Scotia-Weddell Confluence) suspended matter samples were collected for analysis of several biogenic elements including Ba, Si and particulate organic carbon (POC).The good agreement between particulate barium in subsurface water with oxygen minimum concentrations as well as with nitrate depletions suggests that it reflects the intensity of new production over the past season. As a consequence of new production in the Southern Ocean being performed mainly by diatoms, the occurrences of barite and diatoms are related in the water column. In areas characterized by diatom-poor phytoplankton, barite does occur, but in lower concentrations.     

A nomogram method for predicting the movement of oil slicks

In order to obtain quick initial guidance on a first estimation of motion of the spilled oil, a simple manual procedure incorporating advection and spreading processes has been devised. This procedure involves the utilization of a nomogram based on simplified equations. Spill displacements throughout a given forecast period can be easily read from the nomogram. The technique is demonstrated with a real spill case.     

Structure of the Wave Bottom Boundary Layer over Smooth and Rough Bottoms

The comparison of six well-known models of the wave bottom boundary layer shows that they are identical in the case of a smooth bottom but exhibit serious differences for the other types of conditions. The thickness of the wave bottom boundary layer and the coefficient of vertical diffusion of momentum are studied by using the relations of the k-ε-model. The validity of these estimates is checked by comparing the measured and computed values of the friction velocity. This comparison demonstrates fairly good agreement between the results characterized by a coefficient of correlation equal to 0.851. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 54–67, November–December, 2005.     

Viscous model of plate tectonics for the Black Sea region (in relation to the problem of the late Cenozoic evolution of the Black Sea basins)

A numerical model of the Black Sea region (Northeastern Mediterranean) is presented in which it is regarded as a part of the mosaic plate ensemble consisting of the fixed East European platform; the active Arabian, Adriatic, and Pannonian plates; and passive East and West Black Sea and Mysian microplates, which are embedded in a plastically deformable regional orogenic matrix. The fields of displacements, stresses, and deformations in the region are calculated by means of the finite element method within the framework of a linear-viscous rheology approach to a system with nonhomogeneous viscosities. The velocity field obtained is in good agreement with published data of direct observations of plate displacements in the region. In the pressure field, areas of low pressure and decompression are established in the western part of Black Sea and in the south of the Mysian microplate. The poles of rotation of the East and West Black Sea microplates and of the Mysian microplate are computed. For the latter two microplates, significant rotational components are suggested. The East Black Sea microplate acts mostly as indenter, which transmits the collisional motion from the Arabian plate to the southern edge of the East European platform including the Crimea. According to the geodynamical model, the rates of the Cenozoic sedimentation in the Black Sea depression at the collision stage (Oligocene-Pliocene) result from the greater compression of the East Black Sea microplate as compared to the West Black Sea microplate, which, probably, experienced a kind of extension.     

Coping with disaster: Rehabilitating coastal livelihoods and communities

This paper examines lessons from past approaches to natural disasters, as well as early lessons from the post-2004 Asian tsunami rehabilitation, to draw out general principles for rehabilitating livelihoods in poor coastal communities. We contend that avoiding the mistakes of the past requires: (1) a framework for understanding the diversity of coastal people's livelihood strategies and the sources of their vulnerability, (2) a process for designing interventions that build on this understanding in order to strengthen and revitalize coastal communities, including a means of assessing and selecting the most promising livelihood options, and (3) a focus on the longer-term challenge of building future resilience and sustainability in the communities by addressing the root causes of vulnerability.     

Remote sensing and surface POC concentration in the South Atlantic

Several SeaWiFS products have been compared with shipboard data to assess the possibility of using remote sensing to estimate particulate organic carbon (POC) concentration in surface waters. Transmissometer data were collected during six South Atlantic Ventilation Experiment (SAVE) hydrographic expeditions conducted between November 1987 and March 1989 from R/V Knorr, and Melville. A total of 361 beam attenuation profiles were made with a SeaTech transmissometer interfaced with a CTD/rosette. In order to calculate the POC concentration from transmissometer profiles, a regression between beam attenuation and POC for open Atlantic Ocean waters derived from our research in the North Atlantic (North Atlantic Bloom Experiment, NABE) and enhanced by data from the Bermuda Atlantic Time Series Station (BATS) was applied. The profiles were processed and examined as vertical sections of the surface 250 m. The data were collected in two successive years, during the same season, which allowed us to compile a combined data set over the austral summer for examination. Beam attenuation/POC concentrations were integrated down to one attenuation depth with the intent of making comparisons with satellite optical data. No satellite optical data were available for 1987–1989, so the only option was to compare our integrated data with SeaWiFS-derived variables from later years averaged over the same season as SAVE data. Analysis of four SeaWiFS products acquired from 1997 to 2002 demonstrated very low variations from year to year for seasonally averaged data, suggesting that making comparisons of the beam attenuation/POC fields with averaged satellite optical products from later years is a valid (though not optimal) approach for this area. The highest correlation between beam attenuation/POC concentration and remotely derived products was found with normalized water-leaving radiance at 555 nm. Other SeaWiFS-derived variables—chlorophyll concentration, diffuse attenuation coefficient at 490 nm and integral chlorophyll (integrated over one attenuation depth)—were also compared but showed a slightly less satisfactory correlation.     

Numerical investigation of the influence of various factors on the propagation and transformation of solitary waves in the sea

For various stratifications and different types of bottom patterns we study the transformations of solitary perturbations of density appearing in the depth of the sea. In the two-dimensional case, under the assumption that the average dynamic characteristics weakly vary in time as compared with the wave characteristics, we deduce the equations for mean currents and waves taking into account vertical and horizontal viscosity and the diffusion of density. Numerical examples show that the stratification, bottom topography, nonlinearity, mean currents, and dissipation strongly affect both the process of splitting of a solitary wave into wave trains and their amplitude and length. The wave currents exhibit the oscillatory (train-like) character. It is emphasized that, in the case of propagation of solitary perturbations of density with dissipation, it is also important to take into account the combined influence of nonlinearity, currents, bottom topography, and stratification. Translated by Peter V. Malyshev and Dmitry V. Malyshev