33 research outputs found
Long-term evolution of Caspian Sea thermohaline properties reconstructed in an eddy-resolving ocean general circulation model
Decadal variability in Caspian Sea thermohaline properties is
investigated using a high-resolution ocean general circulation model
including sea ice thermodynamics and air–sea interaction forced by prescribed
realistic atmospheric conditions and riverine runoff. The model describes
synoptic, seasonal and climatic variations of sea thermohaline structure,
water balance, and sea level. A reconstruction experiment was conducted for
the period of 1961–2001, covering a major regime shift in the global climate
during 1976–1978, which allowed for an investigation of the Caspian Sea response to
such significant episodes of climate variability. The model reproduced sea
level evolution reasonably well despite the fact that many factors (such as possible
seabed changes and insufficiently explored underground water
infiltration) were not taken into account in the numerical reconstruction.
This supports the hypothesis relating rapid Caspian Sea level rise in
1978–1995 with global climate change, which caused variation in local
atmospheric conditions and riverine discharge reflected in the external
forcing data used, as is shown in the paper. Other effects of the climatic shift
are investigated, including a decrease in salinity in the active layer,
strengthening of its stratification and corresponding diminishing of
convection. It is also demonstrated that water exchange between the three
Caspian basins (northern, middle and southern) plays a crucial role in the
formation of their thermohaline regime. The reconstructed long-term trends in
seawater salinity (general downtrend after 1978), temperature (overall
increase) and density (general downtrend) are studied, including an
assessment of the influence of main surface circulation patterns and model
error accumulation.</p
Compact Modeling Framework v3.0 for high-resolution global ocean–ice–atmosphere models
We present a new version of the Compact Modeling Framework (CMF3.0) developed
for the software environment of stand-alone and coupled global geophysical
fluid models. The CMF3.0 is designed for use on high- and
ultrahigh-resolution models on massively parallel supercomputers.The key features of the previous CMF, version 2.0, are mentioned to reflect
progress in our research. In CMF3.0, the message passing interface (MPI) approach with a
high-level abstract driver, optimized coupler interpolation and I/O
algorithms is replaced with the Partitioned Global Address Space
(PGAS) paradigm communications scheme, while
the central hub architecture evolves into a set of simultaneously working
services. Performance tests for both versions are carried out. As an
addition, some information about the parallel realization of the EnOI
(Ensemble Optimal Interpolation) data assimilation method and the nesting
technology, as program services of the CMF3.0, is presented.</p
Force plate monitoring of human hemodynamics
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background: Noninvasive recording of movements caused by the heartbeat and the blood circulation is known as ballistocardiography. Several studies have shown the capability of a force plate to detect cardiac activity in the human body. The aim of this paper is to present a new method based on differential geometry of curves to handle multivariate time series obtained by ballistocardiographic force plate measurements. Results: We show that the recoils of the body caused by cardiac motion and blood circulation provide a noninvasive method of displaying the motions of the heart muscle and the propagation of the pulse wave along the aorta and its branches. The results are compared with the data obtained invasively during a cardiac catheterization. We show that the described noninvasive method is able to determine the moment of a particular heart movement or the time when the pulse wave reaches certain morphological structure. Conclusions: Monitoring of heart movements and pulse wave propagation may be used e.g. to estimate the aortic pulse wave velocity, which is widely accepted as an index of aortic stiffness wit
iCLAP: Shape Recognition by Combining Proprioception and Touch Sensing
The work presented in this paper was partially supported by the Engineering and Physical Sciences Council (EPSRC) Grant (Ref: EP/N020421/1) and the King’s-China Scholarship Council Ph.D. scholarship
Vegetation succession and climate change across the Plio-Pleistocene transition in eastern Azerbaijan, central Eurasia (2.77–2.45 Ma)
The Plio-Pleistocene transition marked a key moment in global climate history, characterised by the onset of major glaciations in the Northern Hemisphere. The palaeoenvironmental history of the Plio-Pleistocene transition is not well known for the Caspian Sea region, despite its importance for global climate dynamics. Here we present an independently 40Ar/39Ar dated, high-resolution terrestrial palynological record spanning the Plio-Pleistocene boundary based on a lacustrine-marine sedimentary sequence from eastern Azerbaijan. Despite complex pollen transport pathways and the proximity of closely stacked mountain vegetation belts in the Greater and Lesser Caucasus, the record shows that regional vegetation responded to Milankovitch forced glacial-interglacial cycles, tentatively correlated with global climatic records spanning MIS G8 to 98 (∼2.77–2.45 Ma). The persistence of mesophilous forests during glacial times indicates that some settings in the South Caspian Basin acted as glacial refugia, and that vegetation response to glaciations was muted by increased moisture availability, linked to Caspian transgression. The palynological record shows a relationship with global [delta]18O stacks and specifically to the obliquity record. We anticipate that precise correlation with the global climatostratigraphic timescale will allow better understanding of the nature and timing of important transgressive events in the Caspian Sea and their relevance on a global scale
Free Vibrations with Large Amplitude of Axially Loaded Beams on an Elastic Foundation Using the Adomian Modified Decomposition Method
Analytical solutions describing free transverse vibrations with large amplitude of axially loaded Euler–Bernoulli beams for various end restrains resting on a Winkler one-parameter foundation are obtained using the Adomian modified decomposition method (AMDM). The AMDM allows the governing equation to become a recursive algebraic equation, and, after some additional simple mathematical operations, the equations can be cast as an eigenvector problem whose solution results in the calculation of natural frequencies and corresponding closed-form series solution of the mode shapes. Important to the use of the Adomian modified decomposition method is the treatment of the nonlinear Fredholm integral coefficient, which forms part of the governing equation. In addition to the calculation of natural frequencies and mode shapes, investigations are made of the effects on the free vibrations of the Winkler parameter and of increasing the axial loading
The bases of development of systems of control and protection information from internal threats
The present article is devoted to the analysis of information security in the conditions of high-growth hi-tech means of information processing and information security development of systems from internal threats
Seasonal variability of the Caspian Sea three-dimensional circulation, sea level and air-sea interaction
Abstract. A three-dimensional primitive equation model including sea ice thermodynamics and air-sea interaction is used to study seasonal circulation and water mass variability in the Caspian Sea under the influence of realistic mass, momentum and heat fluxes. River discharges, precipitation, radiation and wind stress are seasonally specified in the model, based on available data sets. The evaporation rate, sensible and latent heat fluxes at the sea surface are computed interactively through an atmospheric boundary layer sub-model, using the ECMWF-ERA15 re-analysis atmospheric data and model generated sea surface temperature. The model successfully simulates sea-level changes and baroclinic circulation/mixing features with forcing specified for a selected year. The results suggest that the seasonal cycle of wind stress is crucial in producing basin circulation. Seasonal cycle of sea surface currents presents three types: cyclonic gyres in December–January; Eckman south-, south-westward drift in February–July embedded by western and eastern southward coastal currents and transition type in August–November. Western and eastern northward sub-surface coastal currents being a result of coastal local dynamics at the same time play an important role in meridional redistribution of water masses. An important part of the work is the simulation of sea surface topography, yielding verifiable results in terms of sea level. The model successfully reproduces sea level variability for four coastal points, where the observed data are available. Analyses of heat and water budgets confirm climatologic estimates of heat and moisture fluxes at the sea surface. Experiments performed with variations in external forcing suggest a sensitive response of the circulation and the water budget to atmospheric and river forcing.
NATO (SFP-981063); Russian Foundation for Basic Research (RFBR) (08_05_01055-a)Publisher's Versio