Divergence and dispersion of global eddy propagation from satellite altimetry

2022 ◽  
Keyword(s):  
Rossby Wave ◽  
Satellite Altimetry ◽  
Phase Speed ◽  
Propagation Speed ◽  
Topographic Effects ◽  
Global Pattern ◽  
Systematic Analysis ◽  
Eddy Motion ◽  
External Forcings ◽  
Physically Based

Abstract It is well understood that isolated eddies are presumed to propagate westward intrinsically at the speed of the annual baroclinic Rossby wave. This classic description, however, is known to be frequently violated in both propagation speed and its direction in the real ocean. Here, we present a systematic analysis on the divergence of eddy propagation direction (i.e., global pattern of departure from due west) and dispersion of eddy propagation speed (i.e., zonal pattern of departure from Rossby wave phase speed). Our main findings include the following: 1) A global climatological phase map (the first of its kind to our knowledge) indicating localized direction of most likely eddy propagation has been derived from twenty-eight years (1993-2020) of satellite altimetry, leading to a leaf-like full-angle pattern in its overall divergence. 2) A meridional deflection map of eddy motion is created with prominent equatorward/poleward deflecting zones identified, revealing that it is more geographically correlated rather than polarity determined as previously thought (i.e., poleward for cyclonic eddies and equatorward for anticyclonic ones). 3) The eddy-Rossby wave relationship has a duality nature (waves riding by eddies) in five subtropical bands centered around 27°N and 26°S in the two hemispheres, outside which their relationship has a dispersive nature with dominant waves (eddies) propagating faster in the tropical (extratropical) oceans. Current, wind and topographic effects are major external forcings responsible for the observed divergence and dispersion of eddy propagations. These results are expected to make a significant contribution to eddy trajectory prediction using physically based and/or data-driven models.

scholarly journals Characteristics of Global Oceanic Rossby Wave and Mesoscale Eddies Propagation from Multiple Datasets Analysis

2016 ◽  
Author(s):  
Yunfan Zhang ◽  
Fenglin Tian ◽  
Ge Chen
Keyword(s):  
Rossby Wave ◽  
Phase Speed ◽  
Mesoscale Eddies ◽  
Propagation Speed ◽  
Ocean Current ◽  
Propagation Characteristics ◽  
The North ◽  
Multiple Datasets ◽  
Salinity Data ◽  
The Relationship

Abstract. In this paper we present a research of propagation characteristics of global Rossby wave and mesoscale eddies, and we preliminarily discussing the relationship between them from multiple datasets analysis. By filtering the MSLA-H data and by means of optimized SSH method we have extracted signals of the Rossby wave, and estimated the propagation speed (zonal phase speed) of the Rossby wave and eddies. Validation for the identification of the Rossby wave also has been completed with the Argo temperature and salinity data. The prime focus covers: propagation speed comparison between the Rossby wave and the eddies, propagation characteristics in different regions. Overlaying the signals of the Rossby wave with the signatures of the eddies indicates that the Rossby wave and the eddies propagates together (westward only) in the mid-latitude, but differences appear with increasing of latitude, especially in some areas affected by ocean current, for instance, the West Wind Drift(WWD) and the North Atlantic Drift(NAD). Actually we have found that the currents led the eddies, and the Rossby wave might play an accelerative or moderative role in the eddies propagation, as a result of the velocities of the eddies and the currents were matched well, but comparison between the Rossby wave and the eddies revealed disparity. The findings are useful for understanding the relationship between the Rossby wave and mesoscale eddies.

scholarly journals TSUNAMI PHASE SPEED REDUCTION DUE TO WATER COMPRESSIBILTY

2018 ◽  
pp. 9
Author(s):  
Ali Abdolali ◽  
James T. Kirby
Keyword(s):  
Arrival Time ◽  
Phase Speed ◽  
Propagation Speed ◽  
Frequency Dispersion ◽  
Wave Theory ◽  
Polar Coordinates ◽  
Ocean Bottom ◽  
Tsunami Propagation ◽  
Boussinesq Model ◽  
Tsunami Waves

Most existing tsunami propagation models consider the ocean to be an incompressible, homogenous medium. Recently, it has been shown that a number of physical features can slow the propagation speed of tsunami waves, including wave frequency dispersion, ocean bottom elasticity, water compressibility and thermal or salinity stratification. These physical effects are secondary to the leading order, shallow water or long wave behavior, but still play a quantifiable role in tsunami arrival time, especially at far distant locations. In this work, we have performed analytical and numerical investigations and have shown that consideration of those effects can actually improve the prediction of arrival time at distant stations, compared to incompressible forms of wave equations. We derive a modified Mild Slope Equation for Weakly Compressible fluid following the method proposed by Sammarco et al. (2013) and Abdolali et al. (2015) using linearized wave theory, and then describe comparable extensions to the Boussinesq model of Kirby et al. (2013). Both models account for water compressibility and compression of static water column to simulate tsunami waves. The mild slope model is formulated in plane Cartesian coordinates and is thus limited to medium propagation distances, while the Boussinesq model is formulated in spherical polar coordinates and is suitable for ocean scale simulations.

Intraseasonal to decadal variability of Rossby wave packet properties

2021 ◽  
Author(s):  
Georgios Fragkoulidis ◽  
Volkmar Wirth
Keyword(s):  
Rossby Wave ◽  
Large Scale ◽  
Decadal Variability ◽  
Phase Speed ◽  
Diagnostic Methods ◽  
Temperature And Precipitation ◽  
Ongoing Work ◽  
Large Scale Flow

<p>The large-scale extratropical upper-tropospheric flow tends to organize itself into eastward-propagating Rossby wave packets (RWPs). Investigating the spatiotemporal evolution of RWPs and the underlying physical processes has been beneficial in showcasing the role of the upper-tropospheric flow in temperature and precipitation extremes. The use of recently developed diagnostics of local in space and time wave properties has provided further insight in this regard. Motivated by the above, these diagnostic methods are now being employed to investigate the intraseasonal to decadal variability of key RWP properties such as their amplitude, phase speed, and group velocity in reanalysis datasets. It is shown that these properties exhibit a distinct seasonal and interregional variability, while interesting patterns thereof emerge. Moreover, the interannual and long-term variability in these RWP properties is explored and significant decadal trends for specific regions and seasons are highlighted. Ongoing work aims at further utilizing the presented diagnostics and analyses toward an improved understanding of the extratropical large-scale flow variability from weather to climate time scales.</p>

scholarly journals Global trends of hand and wrist trauma: a systematic analysis of fracture and digit amputation using the Global Burden of Disease 2017 Study

2020 ◽  
Vol 26 (Supp 1) ◽  
pp. i115-i124 ◽  
Author(s):  
Christopher Stephen Crowe ◽  
Benjamin Ballard Massenburg ◽  
Shane Douglas Morrison ◽  
James Chang ◽  
Jeffrey Barton Friedrich ◽  
...  
Keyword(s):  
Global Burden ◽  
Hand Trauma ◽  
Uncertainty Interval ◽  
Global Pattern ◽  
Systematic Analysis ◽  
Fatal Injury ◽  
Global Trends ◽  
Wrist Fractures ◽  
Wrist Trauma ◽  
Global Burden Of Diseases

BackgroundAs global rates of mortality decrease, rates of non-fatal injury have increased, particularly in low Socio-demographic Index (SDI) nations. We hypothesised this global pattern of non-fatal injury would be demonstrated in regard to bony hand and wrist trauma over the 27-year study period.MethodsThe Global Burden of Diseases, Injuries, and Risk Factors Study 2017 was used to estimate prevalence, age-standardised incidence and years lived with disability for hand trauma in 195 countries from 1990 to 2017. Individual injuries included hand and wrist fractures, thumb amputations and non-thumb digit amputations.ResultsThe global incidence of hand trauma has only modestly decreased since 1990. In 2017, the age-standardised incidence of hand and wrist fractures was 179 per 100 000 (95% uncertainty interval (UI) 146 to 217), whereas the less common injuries of thumb and non-thumb digit amputation were 24 (95% UI 17 to 34) and 56 (95% UI 43 to 74) per 100 000, respectively. Rates of injury vary greatly by region, and improvements have not been equally distributed. The highest burden of hand trauma is currently reported in high SDI countries. However, low-middle and middle SDI countries have increasing rates of hand trauma by as much at 25%.ConclusionsCertain regions are noted to have high rates of hand trauma over the study period. Low-middle and middle SDI countries, however, have demonstrated increasing rates of fracture and amputation over the last 27 years. This trend is concerning as access to quality and subspecialised surgical hand care is often limiting in these resource-limited regions.

scholarly journals Testing the Sensitivity of the Extratropical Response to the Location, Amplitude, and Propagation Speed of Tropical Convection

2018 ◽  
Vol 75 (2) ◽  
pp. 639-655 ◽  
Author(s):  
Michael Goss ◽  
Steven B. Feldstein
Keyword(s):  
Southern Oscillation ◽  
Phase Speed ◽  
Propagation Speed ◽  
Warm Pool ◽  
Tropical Convection ◽  
Relative Amplitude ◽  
Convective Heating ◽  
Central Pacific ◽  
Model Calculations ◽  
Heating Anomaly

Abstract The dynamical core of a dry global model is used to investigate the role of central Pacific versus warm pool tropical convection on the extratropical response over the North Pacific and North America. A series of model runs is performed in which the amplitude of the warm pool (WP) and central Pacific (CP) heating anomalies associated with the MJO and El Niño–Southern Oscillation (ENSO) is systematically varied. In addition, model calculations based on each of the eight MJO phases are performed, first using stationary heating, and then with heating corresponding to a 48-day MJO cycle and to a 32-day MJO cycle. In all model runs, the extratropical response to tropical convection occurs within 7–10 days of the convective heating. The response is very sensitive to the relative amplitude of the heating anomalies. For example, when heating anomalies in the WP and CP have similar amplitude but opposite sign, the amplitude of the extratropical response is much weaker than is typical for the MJO and ENSO. For the MJO, when the WP heating anomaly is much stronger than the CP heating anomaly (vice versa for ENSO), the extratropical response is amplified. For the MJO heating, it is found that the extratropical responses to phases 4 and 8 are most distinct. A likely factor contributing to this distinctiveness involves the relative amplitude of the two heating anomalies. The stationary and moving (48- and 32-day) heating responses are very similar, revealing a lack of sensitivity to the MJO phase speed.

Stationary waves on an inclined sheet of viscous fluid at high Reynolds and moderate Weber numbers

1996 ◽  
Vol 307 ◽  
pp. 191-229 ◽  
Author(s):  
Jeng-Jong Lee ◽  
Chiang C. Mei
Keyword(s):  
Dynamical System ◽  
Phase Speed ◽  
Propagation Speed ◽  
Reynolds Numbers ◽  
Homoclinic Orbits ◽  
Finite Amplitude ◽  
Stationary Waves ◽  
Asymptotic Equations ◽  
Wave Propagation Speed ◽  
High Reynolds

A theory is described for the nonlinear waves on the surface of a thin film flowing down an inclined plane. Attention is focused on stationary waves of finite amplitude and long wavelength at high Reynolds numbers and moderate Weber numbers. Based on asymptotic equations accurate to the second order in the depth-to-wavelength ratio, a third-order dynamical system is obtained after changing to the frame of reference moving at the wave propagation speed. By examining the fixed-point stability of the dynamical system, parametric regimes of heteroclinc orbits and Hopf bifurcations are delineated. Extensive numerical experiments guided by the linear analyses reveal a variety of bifurcation scenarios as the phase speed deviates from the Hopf-bifurcation thresholds. These include homoclinic bifurcations which lead to homoclinic orbits corresponding to well separated solitary waves with one or several humps, some of which occur after passing through chaotic zones generated by period-doublings. There are also cases where chaos is the ultimate state following cascades of period-doublings, as well as cases where only limit cycles prevail. The dependence of bifurcation scenarios on the inclination angle, and Weber and Reynolds numbers is summarized.

scholarly journals Local Rossby Wave Packet Amplitude, Phase Speed, and Group Velocity: Seasonal Variability and Their Role in Temperature Extremes

2020 ◽  
Vol 33 (20) ◽  
pp. 8767-8787 ◽  
Author(s):  
Georgios Fragkoulidis ◽  
Volkmar Wirth
Keyword(s):  
Group Velocity ◽  
Rossby Wave ◽  
Model Simulation ◽  
Phase Speed ◽  
Meridional Wind ◽  
Reanalysis Data ◽  
Spatiotemporal Variability ◽  
Temperature Extremes ◽  
Time Period ◽  
Real Atmosphere

AbstractTransient Rossby wave packets (RWPs) are a prominent feature of the synoptic to planetary upper-tropospheric flow at the midlatitudes. Their demonstrated role in various aspects of weather and climate prompts the investigation of characteristic properties like their amplitude, phase speed, and group velocity. Traditional frameworks for the diagnosis of the two latter have so far remained nonlocal in space or time, thus preventing a detailed view on the spatiotemporal evolution of RWPs. The present work proposes a method for the diagnosis of horizontal Rossby wave phase speed and group velocity locally in space and time. The approach is based on the analytic signal of upper-tropospheric meridional wind velocity and RWP amplitude, respectively. The new diagnostics are first applied to illustrative examples from a barotropic model simulation and the real atmosphere. The main seasonal and interregional variability features of RWP amplitude, phase speed, and group velocity are then explored using ERA5 reanalysis data for the time period 1979–2018. Apparent differences and similarities in these respects between the Northern and Southern Hemispheres are also discussed. Finally, the role of RWP amplitude and phase speed during central European short-lived and persistent temperature extremes is investigated based on changes of their distribution compared to the climatology of the region. The proposed diagnostics offer insight into the spatiotemporal variability of RWP properties and allow the evaluation of their implications at low computational demands.

On the Linkage Between Rossby Wave Phase Speed, Atmospheric Blocking, and Arctic Amplification

2020 ◽  
Vol 47 (19) ◽  
Author(s):  
Jacopo Riboldi ◽  
François Lott ◽  
Fabio D'Andrea ◽  
Gwendal Rivière
Keyword(s):  
Rossby Wave ◽  
Phase Speed ◽  
Arctic Amplification ◽  
Atmospheric Blocking ◽  
Wave Phase

scholarly journals The decay of cyclonic eddies by Rossby wave radiation

1998 ◽  
Vol 361 ◽  
pp. 237-252 ◽  
Author(s):  
N. ROBB McDONALD
Keyword(s):  
Shallow Water ◽  
Explicit Expression ◽  
Energy Flux ◽  
Rossby Wave ◽  
Potential Vorticity ◽  
Phase Speed ◽  
Wave Radiation ◽  
Conservation Of Energy ◽  
Radiation Induced ◽  
General Method

It is argued that because shallow water cyclones on a β-plane drift westward at a speed equal to an available Rossby wave phase speed, they must radiate energy and cannot, therefore, be steady. The form of the Rossby wave wake accompanying a quasi-steady cyclone is calculated and the energy flux in the radiated waves determined. Further, an explicit expression for the radiation-induced northward drift of the cyclone is obtained. A general method for determining the effects of the radiation on the radius and amplitude of the vortex based on conservation of energy and potential vorticity is given. An example calculation for a cyclone with a ‘top-hat’ profile is presented, demonstrating that the primary effect of the radiation is to decrease the radius of the vortex. The dimensional timescale associated with the decay of oceanic vortices is of the order of several months to a year.

scholarly journals Chaotic mixing and transport in Rossby-wave critical layers

1997 ◽  
Vol 334 ◽  
pp. 315-351 ◽  
Author(s):  
KEITH NGAN ◽  
THEODORE G. SHEPHERD
Keyword(s):  
Rossby Wave ◽  
Phase Speed ◽  
Wave Model ◽  
Chaotic Advection ◽  
Transient Wave ◽  
Single Wave ◽  
Rossby Wave Breaking ◽  
Lobe Dynamics ◽  
Critical Layers ◽  
Mixing And Transport

A simple, dynamically consistent model of mixing and transport in Rossby-wave critical layers is obtained from the well-known Stewartson–Warn–Warn (SWW) solution of Rossby-wave critical-layer theory. The SWW solution is thought to be a useful conceptual model of Rossby-wave breaking in the stratosphere. Chaotic advection in the model is a consequence of the interaction between a stationary and a transient Rossby wave.Mixing and transport are characterized separately with a number of quantitative diagnostics (e.g. mean-square dispersion, lobe dynamics, and spectral moments), and with particular emphasis on the dynamics of the tracer field itself. The parameter dependences of the diagnostics are examined: transport tends to increase monotonically with increasing perturbation amplitude whereas mixing does not. The robustness of the results is investigated by stochastically perturbing the transient-wave phase speed. The two-wave chaotic advection model is contrasted with a stochastic single-wave model. It is shown that the effects of chaotic advection cannot be captured by stochasticity alone.

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