165 research outputs found
ANALYSIS AND EVALUATION OF MEASURES TAKEN AT THE FEDERAL AND REGIONAL LEVELS OF GOVERNMENT FOR THE EXIT OF THE RUSSIAN ECONOMY FROM THE PANDEMIC
The COVID-19 epidemic has become a serious challenge for the economies of all countries of the world. The consequences of the fight against the spread of the virus have led to serious complications in the Russian economy. This article analyses the measures taken by the federal and regional governments aimed at curbing the spread of the pandemic, as well as supporting the economy of Russia and its subjects. The paper presents foreign experience on the measures taken and a comparative analysis between the countries. In addition, the authors study the influence of government decisions and their effectiveness on the basis of scientific articles, estimates and statistics published in the mass media, forecasts of the Ministry of Economic Development of the Russian Federation, reports of the Federal State Statistic Service
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Nearâsurface dynamics of a separated jet in the coastal transition zone off Oregon
Threeâdimensional circulation in the coastal transition zone (CTZ) off Oregon is
studied using a 3 km resolution model based on the Regional Ocean Modeling System.
The study period is spring and summer 2002, when extensive observations were available
from the northeastern Pacific component of the Global Ocean Ecosystems Dynamics
project. Our main focus is on nearâsurface transports, particularly in an area off Cape
Blanco where an energetic coastal current is separated in the CTZ. Comparisons with
available observations (velocities from midshelf moorings, surface velocities from highfrequency
radars, satellite sea surface temperature maps, alongâtrack sea surface height
altimetry, and SeaSoar hydrography) show that the model reproduces qualitatively
correctly the flow structure and variability in the study area. The nearâsurface flow
behavior during 26 July to 21 August, a lateâsummer time period of strong, timeâvariable
southward winds, is examined. During that period the coastal jet separates from the
continental shelf around Cape Blanco (43°N). The energetic separated jet continues to flow
southward in a nearâcoastal region between 42.2°N and 43°N. It subsequently turns around
42°N to flow westward offshore past 127°W. Relatively vigorous upâ and downwelling
is found concentrated in the region of the separated jet. Frontogenesis secondary
circulation, nonlinear effects of the relative vorticity on the ageostrophic Ekman transport,
and submesoscale instabilities contribute to the vertical circulation within the jet. Vertical
velocities are found to reach 50 m dâ»Âč in the offshore part of the jet and 100 m dâ»Âč in
the nearâcoastal part, where the jet is aligned with the wind direction.Keywords: Oregon, Coastal transition zone, Near-surface transports, CT
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Combined Effects of Wind-Driven Upwelling and Internal Tide on the Continental Shelf
Internal tides on the continental shelf can be intermittent as a result of changing hydrographic conditions
associated with wind-driven upwelling. In turn, the internal tide can affect transports associated with upwelling.
To study these processes, simulations in an idealized, alongshore uniform setup are performed utilizing
the hydrostatic Regional Ocean Modeling System (ROMS) with conditions corresponding, as closely as
possible, to the central Oregon shelf. ââWind onlyââ (WO), ââtide onlyââ (TO), and ââtide and windââ (TW)
solutions are compared, utilizing cases with constant upwelling-favorable wind stress as well as with timevariable
observed stress. The tide is forced by applying cross-shore barotropic flow at the offshore boundary
with intensity sufficient to generate an internal tide with horizontal velocity amplitudes near 0.15 m s21,
corresponding to observed levels. The internal tide affects the subinertial circulation, mostly through the
changes in the bottom boundary layer variability, resulting in a larger bottom stress and a weaker depthaveraged
alongshore current in the TW case compared to WO. The spatial variability of the cross-shore and
vertical volume transport is also affected. Divergence in the Reynolds stress associated with the baroclinic
tidal flow contributes to the tidally averaged cross-shore momentum balance. Internal waves cause highfrequency
variability in the turbulent kinetic energy in both the bottom and surface boundary layers, causing
periodic restratification of the inner shelf in the area of the upwelling front. Increased vertical shear in the
horizontal velocity resulting from the superposition of the upwelling jet and the internal tide results in intermittent
patches of intensified turbulence in the midâwater column. Variability in stratification associated
with upwelling can affect not only the propagation of the internal tide on the shelf, but also the barotropic-tobaroclinic
energy conversion on the continental slope, in this case changing the classification of the slope from
nearly critical to supercritical such that less barotropic tidal energy is converted to baroclinic and a larger
fraction of the baroclinic energy is radiated into the open ocean
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Spatial and Temporal Variability of the M2 Internal Tide Generation and Propagation on the Oregon Shelf
A 1-km-horizontal-resolution model based on the Regional Ocean Modeling System is implemented along the Oregon coast to study average characteristics and intermittency of the Mâ internal tide during summer upwelling. Wind-driven and tidally driven flows are simulated in combination, using realistic bathymetry, atmospheric forcing, and boundary conditions. The study period is April through August 2002, when mooring velocities are available for comparison. Modeled subtidal and tidal variability on the shelf are in good quantitative agreement with moored velocity time series observations. Depth-integrated baroclinic tidal energy flux (EF), its divergence, and topographic energy conversion (TEC) from the barotropic to baroclinic tide are computed from high-pass-filtered, harmonically analyzed model results in a series of 16-day time windows. Model results reveal several âhot spotsâ of intensive TEC on the slope. At these locations, TEC is well balanced by EF divergence. Changes in background stratification and currents associated with wind-driven upwelling and downwelling do not appreciably affect TEC hot spot locations but may affect intensity of internal tide generation at those locations. Relatively little internal tide is generated on the shelf. Areas of supercritical slope near the shelf break partially reflect baroclinic tidal energy to deeper water, contributing to spatial variability in seasonally averaged on-shelf EF. Despite significant temporal and spatial variability in the internal tide, the alongshore-integrated flux of internal tide energy onto the Oregon shelf, where it is dissipated, does not vary much with time. Approximately 65% of the Mâ baroclinic tidal energy generated on the slope is dissipated there, and the rest is radiated toward the shelf and interior ocean in roughly equal proportions. An experiment with smoother bathymetry reveals that slope-integrated TEC is more sensitive to bathymetric roughness than on-shelf EF.KEYWORDS: Continental shelf/slope, Tides, Internal waves, Hindcasts, North Pacific Ocean, Regional model
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Intensified Diurnal Tides along the Oregon Coast
Intensified diurnal tides are found along portions of the Oregon shelf (U.S. West Coast) based on analyses
of high-frequency (HF) radar surface current data and outputs of a 1-km resolution ocean circulation model.
The Kâ tidal currents with magnitudes near 0.07 m sâ»Âč over a wider part of the shelf (Heceta Bank complex;
44°â44.5°N), previously predicted by Erofeeva et al., are confirmed here by newly available HF radar data.
Intensified diurnal tides are also found along the narrow shelf south of Heceta Bank. In the close vicinity of
Cape Blanco (42.8°N), diurnal tidal currents (Kâ and Oâ constituents combined) may reach 0.3 m sâ»Âč. Appreciable
differences in diurnal tide intensity are found depending on whether the model is forced with tides
and winds (TW) or only tides. Also, diurnal variability in wind forcing is found to affect diurnal surface
velocities. For the case forced by tides alone, results strongly depend on whether the model ocean is stratified
[tides only, stratified (TOS)] or not [tides only, no stratification (TONS)]. In case TONS, coastal-trapped
waves at diurnal frequencies do not occur over the narrow shelf south of 43.5°N, consistent with the dispersion
analysis of a linear shallow-water model. However, in case TOS, diurnal tides are intensified in that area,
associated with the presence of coastal-trapped waves. Case TW produces the strongest modeled diurnal tidal
motions over the entire Oregon shelf, partially due to cross-shore tidal displacement (advection) of alongshore
subinertial currents. At Cape Blanco, diurnal tidal variability dominates the modeled relative vorticity
spectrum, suggesting that tides may influence the separation of the alongshore coastal jet at that location.Keywords: Boundary currents, Dynamics, Topographic effects, Currents, Ocean dynamics, Fronts, Circulation/ Dynamic
Coastal Ocean Forecasting: science foundation and user benefits
The advancement of Coastal Ocean Forecasting Systems (COFS) requires the support of continuous scientific progress addressing: (a) the primary mechanisms driving coastal circulation; (b) methods to achieve fully integrated coastal systems (observations and models), that are dynamically embedded in larger scale systems; and (c) methods to adequately represent air-sea and biophysical interactions. Issues of downscaling, data assimilation, atmosphere-wave-ocean couplings and ecosystem dynamics in the coastal ocean are discussed. These science topics are fundamental for successful COFS, which are connected to evolving downstream applications, dictated by the socioeconomic needs of rapidly increasing coastal populations
Model-data synthesis and high resolution simulation of the Bering Sea
The Bering Sea is the source of over 50% of the total US fish catch and the home to immense populations of birds and marine mammals. This extraordinarily productive ecosystem is vulnerable to climate regime shifts that have occurred over the past decades. These regime shifts are closely linked to warming and cooling of the atmosphere and ocean, and the coincident retreat or expansion of the sea ice cover with strong interannual and decadal variability. Here we investigate changes in the Bering ice/ocean system in recent years. One of key tools for this investigation is the Bering Ecosystem STudy ice-ocean Modeling and Assimilation System (BESTMAS) for synthesis and modeling of the Bering ice/ocean system
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Modeling Bottom Mixed Layer Variability on the Mid-Oregon Shelf during Summer Upwelling
Results from a model of wind-driven circulation are analyzed to study spatial and temporal variability in
the bottom mixed layer (BML) on the mid-Oregon shelf in summer 2001. The model assimilates acoustic
Doppler profiler velocities from two cross-shore lines of moorings 90 km apart to provide improved
accuracy of near-bottom velocities and turbulence variables in the area between the mooring lines. Model
results suggest that the response of the BML thickness to upwelling- and downwelling-favorable winds
differs qualitatively between an area of âsimpleâ bathymetric slope at 45°N and a wider shelf area east of
Stonewall Bank (44.5°N). At 45°N, the BML grows in response to downwelling-favorable conditions, in
agreement with known theories. East of Stonewall Bank, the BML thickness is increased following upwelling
events. In this area, the southward upwelling jet detaches from the coast and flows over a wider part
of the Oregon shelf, creating conditions for Ekman pumping near the bottom. Based on computations of
bottom stress curl, the vertical pumping velocity in this area may reach 15 m dayâ»Âč following periods of
intensified upwelling-favorable winds. A column of denser, near-bottom water upwelled over the Ekman
flow convergence area is tilted as a result of vertical shear in horizontal velocities, causing unstable stratification
and convective overturning. As a result of this process, BML thickness values east of Stonewall
Bank can be in excess of 20 m following upwelling, comparable to maximum values at 45°N following
downwelling
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Variational assimilation of satellite observations in a coastal ocean model off Oregon
Satellite along-track sea surface height (SSH) and multisatellite sea surface temperature (SST) maps are assimilated in a coastal ocean circulation model off Oregon. The study period is JuneâOctober 2005, featuring intensive separation of the coastal upwelling jets in the eddy-dominated coastal transition zone (CTZ). The data assimilation (DA) system combines the nonlinear Regional Ocean Modeling System (ROMS) and the Advanced Variational Regional Ocean Representer Analyzer (AVRORA) tangent linear and adjoint codes developed by our group. The variational representer DA method is implemented in a series of 6 day time windows, with initial conditions corrected at the beginning of each window. To avoid the problem of matching the model and observed SSH mean levels, the observed SSH slope has been assimilated. Location, timing, and intensity of jets and eddies in the CTZ are constrained, to improve accuracy of nonlinear model analyses and forecasts. In the case assimilating SSH alone, the geometry of the SST front is improved. SSH assimilation results in the cross-shore transport more uniformly distributed along the coast than in the free run model. An outer front is identified in the DA analyses at a distance of 200 km from the coast. A strong subsurface horizontal temperature gradient across this front influences the depth of the thermocline in an area between the front and the continental slope. The DA correction term is comparable in magnitude to dominant terms in the volume-integrated heat equation. The time-averaged DA correction term in the volume-integrated heat balance is closer to 0 in the combined SSH-SST assimilation case, than in the case assimilating SSH alone.This is the publisher's final pdf. The published article is copyrighted by American Geophysical Union and can be found at: http://www.agu.org/journals/jc/index.shtm
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