scholarly journals Lagrangian betweenness as a measure of bottlenecks in dynamical systems with oceanographic examples

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Enrico Ser-Giacomi ◽  
Alberto Baudena ◽  
Vincent Rossi ◽  
Mick Follows ◽  
Sophie Clayton ◽  
...  
Keyword(s):  
Dynamical Systems ◽  
Network Theory ◽  
Fluid Transport ◽  
Oceanic Circulation ◽  
Spatial Correlations ◽  
Effective Measure ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Spatio Temporal

AbstractThe study of connectivity patterns in networks has brought novel insights across diverse fields ranging from neurosciences to epidemic spreading or climate. In this context, betweenness centrality has demonstrated to be a very effective measure to identify nodes that act as focus of congestion, or bottlenecks, in the network. However, there is not a way to define betweenness outside the network framework. By analytically linking dynamical systems and network theory, we provide a trajectory-based formulation of betweenness, called Lagrangian betweenness, as a function of Lyapunov exponents. This extends the concept of betweenness beyond the context of network theory relating hyperbolic points and heteroclinic connections in any dynamical system to the structural bottlenecks of the network associated with it. Using modeled and observational velocity fields, we show that such bottlenecks are present and surprisingly persistent in the oceanic circulation across different spatio-temporal scales and we illustrate the role of these areas in driving fluid transport over vast oceanic regions. Analyzing plankton abundance data from the Kuroshio region of the Pacific Ocean, we find significant spatial correlations between measures of diversity and betweenness, suggesting promise for ecological applications.

scholarly journals Lewis fry Richardson Medal Lecture – How many modes are neededto predict climate bifurcations?: Lessons from an experiment

2021 ◽  
Author(s):  
Bérengère Dubrulle ◽  
François Daviaud ◽  
Davide Faranda ◽  
Louis Marié ◽  
Brice Saint-Michel
Keyword(s):  
Degrees Of Freedom ◽  
Climate Models ◽  
Environmental Policies ◽  
Climate Projections ◽  
Finite Resolution ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Lewis Fry Richardson ◽  
Do So

Abstract. According to everyone’s experience, predicting the weather reliably over more than 8 days seems an impossible taskfor our best weather agencies. At the same time, politicians and citizens are asking scientists for climate projections severaldecades into the future to guide economic and environmental policies, especially regarding the maximum admissible emissions of CO2. To what extent is this request scientifically admissible? In this lecture we will investigate this question, focusing on the topic of predictions of transitions between metastable statesof the atmospheric or oceanic circulations. Two relevant exemples are the switching between zonal and blocked atmosphericcirculation at midlatitudes and the alternance of El Niño and La Niña phases in the Pacific ocean. The main issue is whetherpresent climate models, that necessarily have a finite resolution and a smaller number of degrees of freedom than the actualterrestrial system, are able to reproduce such spontaneous or forced transitions. To do so, we will draw an analogy betweenclimate observations and results obtained in our group on a laboratory-scale, turbulent, von Kármán flow, in which spontaneoustransitions between different states of the circulation take place. We will detail the analogy, and investigate the nature of thetransitions, the number of degrees of freedom that characterizes the latter and discuss the effect of reducing the number ofdegrees of freedom in such systems. We will also discuss the role of fluctuations and their origin, and stress the importance ofdescribing very small scales to capture fluctuations of correct intensity and scale.

scholarly journals ROLE OF THE COLORED NOISE IN SPATIO-TEMPORAL BEHAVIOR OF TWO COMPETING SPECIES

2005 ◽  
Vol 05 (02) ◽  
pp. L337-L342 ◽  
Author(s):  
D. VALENTI ◽  
A. FIASCONARO ◽  
B. SPAGNOLO
Keyword(s):  
Noise Intensity ◽  
Large Scale ◽  
Colored Noise ◽  
Spatial Distributions ◽  
Temporal Behavior ◽  
Spatial Correlations ◽  
Interacting Species ◽  
Spatio Temporal ◽  
Nonmonotonic Behavior

We study the spatial distributions of two randomly interacting species, in the presence of an external multiplicative colored noise. The dynamics of the ecosystem is described by a coupled map lattice model. We find a nonmonotonic behavior in the formation of large scale spatial correlations as a function of the multiplicative colored noise intensity. This behavior is shifted towards higher values of the noise intensity for increasing correlation time of the noise.

scholarly journals Observed Interhemispheric Meridional Heat Transports and the Role of the Indonesian Throughflow in the Pacific Ocean

2019 ◽  
Vol 32 (24) ◽  
pp. 8523-8536 ◽  
Author(s):  
Kevin E. Trenberth ◽  
Yongxin Zhang
Keyword(s):  
El Niño ◽  
El Nino ◽  
Heat Content ◽  
Indonesian Throughflow ◽  
Annual Cycles ◽  
Surface Energy Flux ◽  
The Pacific ◽  
Tasman Sea ◽  
The Pacific Ocean

Abstract The net surface energy flux is computed as a residual of the energy budget using top-of-atmosphere radiation combined with the divergence of the column-integrated atmospheric energy transports, and then used with the vertically integrated ocean heat content tendencies to compute the ocean meridional heat transports (MHTs). The mean annual cycles and 12-month running mean MHTs as a function of latitude are presented for 2000–16. Effects of the Indonesian Throughflow (ITF), associated with a net volume flow around Australia accompanied by a heat transport, are fully included. Because the ITF-related flow necessitates a return current northward in the Tasman Sea that relaxes during El Niño, the reduced ITF during El Niño may contribute to warming in the south Tasman Sea by allowing the East Australian Current to push farther south even as it gains volume from the tropical waters not flowing through the ITF. Although evident in 2015/16, when a major marine heat wave occurred, these effects can be overwhelmed by changes in the atmospheric circulation. Large interannual MHT variability in the Pacific is 4 times that of the Atlantic. Strong relationships reveal influences from the southern subtropics on ENSO for this period. At the equator, northward ocean MHT arises mainly in the Atlantic (0.75 PW), offset by the Pacific (−0.33 PW) and Indian Oceans (−0.20 PW) while the atmosphere transports energy southward (−0.35 PW). The net equatorial MHT southward (−0.18 PW) is enhanced by −0.1 PW that contributes to the greater warming of the southern (vs northern) oceans.

scholarly journals Dissolution of cobalt and zinc from natural and anthropogenic dusts in seawater

2010 ◽  
Vol 7 (6) ◽  
pp. 1927-1936 ◽  
Author(s):  
C.-E. Thuróczy ◽  
M. Boye ◽  
R. Losno
Keyword(s):  
Mixed Layer ◽  
Flow Reactor ◽  
Anthropogenic Sources ◽  
Anthropogenic Aerosol ◽  
Surface Ocean ◽  
Anthropogenic Inputs ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Voltammetric Methods

Abstract. Atmospheric dust inputs to the surface ocean are a major source of trace metals likely to be bio-available for phytoplankton after their dissolution in seawater. Among them, cobalt (Co) and zinc (Zn) are essential for phytoplankton growth and for the distribution of the major groups such as coccolithophorids, cyanobacteria and diatoms. The solubility in seawater of Co and Zn present in natural and anthropogenic dusts was studied using an open-flow reactor with and without light irradiation. Those dusts can be transported in the atmosphere by the wind before being deposited to the surface ocean. The analyses of cobalt and zinc were conducted using voltammetric methods and the global elemental composition of dust was determined by ICP-AES. This study highlighted the role of the dust origin in revealing the solubility characteristics. Much higher dust solubility was found for zinc as compared to cobalt; cobalt in anthropogenic particles was much more soluble (0.78%) in seawater after 2 h of dissolution than Co in natural particles (0.14%). Zinc showed opposite solubility, higher in natural particles (16%) than in anthropogenic particles (5.2%). A natural dust event to the surface ocean could account for up to 5% of the cobalt inventory and up to 50% of the Zn inventory in the mixed layer in the Pacific Ocean whereas the cobalt and zinc inventories in the mixed layer of the Atlantic Ocean might already include the effects of natural dust inputs and the subsequent metal dissolution. Anthropogenic sources to the surface ocean could be as important as the natural sources, but a better estimate of the flux of anthropogenic aerosol to the surface ocean is needed to further estimate the anthropogenic inputs. Variations in natural and anthropogenic inputs may induce large shifts in the Co/Zn ratio in the surface ocean; hence it could impact the phytoplankton community structure.

scholarly journals Surface ocean iron fertilization: The role of airborne volcanic ash from subduction zone and hot spot volcanoes and related iron fluxes into the Pacific Ocean

2011 ◽  
Vol 25 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Nazlı Olgun ◽  
Svend Duggen ◽  
Peter Leslie Croot ◽  
Pierre Delmelle ◽  
Heiner Dietze ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Subduction Zone ◽  
Volcanic Ash ◽  
Hot Spot ◽  
Surface Ocean ◽  
Iron Fertilization ◽  
The Pacific ◽  
The Pacific Ocean

Lagrangian betweenness: detecting fluid transport bottlenecks in oceanic flows

2021 ◽  
Author(s):  
Enrico Ser-Giacomi ◽  
Alberto Baudena ◽  
Vincent Rossi ◽  
Mick Follows ◽  
Ruggero Vasile ◽  
...  
Keyword(s):  
Fluid Transport ◽  
Marine Ecology ◽  
Tracer Transport ◽  
Effective Measure ◽  
Finite Time Lyapunov Exponents ◽  
Novel Approach ◽  
High Betweenness ◽  
Potential Applications ◽  
Spatio Temporal ◽  
Circumpolar Current

<p> </p><p>The study of connectivity patterns in networks has brought novel insights across diverse fields ranging from neurosciences to epidemic spreading or climate. In this context, betweenness centrality has demonstrated to be a very effective measure to identify nodes that act as focus of congestion, or bottlenecks, in the network. However, there is not a way to define betweenness outside the network framework. Here we introduce the “Lagrangian betweenness”, an analogous quantity which relies only on the information provided by trajectories sampled across a generic dynamical system in the form of Finite Time Lyapunov Exponents, a widely used metric in Dynamical Systems Theory and Lagrangian oceanography. Our theoretical framework reveals a link between regions of high betweenness and the hyperbolic behavior of trajectories in the system. For example, it identifies bottlenecks in fluid flows where particles are first brought together and then widely dispersed. This has many potential applications including marine ecology and pollutant dispersal. We first test our definition of betweenness in an idealized double-gyre flow system. We then apply it in the characterization of transport by real geophysical flows in the semi-enclosed Adriatic Sea and the Kerguelen region of the highly turbulent Antarctic Circumpolar Current. In both cases, patterns of Lagrangian betweenness identify hidden bottlenecks of tracer transport that are surprisingly persistent across different spatio-temporal scales. In the marine context, high Lagrangian betweenness regions represent the optimal compromise between the heterogeneity of water origins and destinations, suggesting that they may be associated with relevant diversity reservoirs and hot-spots in marine ecosystems. Our new metric could also provide a novel approach useful for the management of environmental resources, informing strategies for marine spatial planning, and for designing observational networks to control pollutants or early-warning signals of climatic risks. </p>

Bordering on Crisis

2021 ◽  
pp. 269-289
Author(s):  
Brian Wilson ◽  
Nora Johnson
Keyword(s):  
United Nations ◽  
Crisis Management ◽  
Security Council ◽  
Crisis Response ◽  
United Nations Security Council ◽  
The Pacific ◽  
Terrorist Organization ◽  
Scant Attention ◽  
The Pacific Ocean

A vessel plying the Pacific Ocean with approximately 500 migrants, some of whom might have deadly contagions, along with members of a terrorist organization, is emblematic of contemporary multiagency crisis response challenges: vague reports, agencies with overlapping authorities, balancing competing legal considerations, and an urgency to act. While crisis management isn’t new, the strategic response landscape now includes formal collaborative frameworks. A key element of interagency alignment involves lawyers who are increasingly being called upon to advise in crisis situations. More than a dozen states, multilateral instruments, and United Nations Security Council resolutions formally acknowledge the benefits of collaboration to address threats, yet the elements and competencies, as well as inclusion, of crisis lawyering receive scant attention. This chapter examines the role of an attorney in an inter-agency crisis management and includes “Rules for Crisis Lawyering in a Multiagency Environment.”

scholarly journals Persistence of deeply sourced iron in the Pacific Ocean

2015 ◽  
Vol 112 (5) ◽  
pp. 1292-1297 ◽  
Author(s):  
Tristan J. Horner ◽  
Helen M. Williams ◽  
James R. Hein ◽  
Mak A. Saito ◽  
Kevin W. Burton ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Carbon Fixation ◽  
Global Ocean ◽  
Oceanic Circulation ◽  
Multiple Sources ◽  
Central Pacific ◽  
Central Pacific Ocean ◽  
The Past ◽  
The Pacific ◽  
The Pacific Ocean

Biological carbon fixation is limited by the supply of Fe in vast regions of the global ocean. Dissolved Fe in seawater is primarily sourced from continental mineral dust, submarine hydrothermalism, and sediment dissolution along continental margins. However, the relative contributions of these three sources to the Fe budget of the open ocean remains contentious. By exploiting the Fe stable isotopic fingerprints of these sources, it is possible to trace distinct Fe pools through marine environments, and through time using sedimentary records. We present a reconstruction of deep-sea Fe isotopic compositions from a Pacific Fe−Mn crust spanning the past 76 My. We find that there have been large and systematic changes in the Fe isotopic composition of seawater over the Cenozoic that reflect the influence of several, distinct Fe sources to the central Pacific Ocean. Given that deeply sourced Fe from hydrothermalism and marginal sediment dissolution exhibit the largest Fe isotopic variations in modern oceanic settings, the record requires that these deep Fe sources have exerted a major control over the Fe inventory of the Pacific for the past 76 My. The persistence of deeply sourced Fe in the Pacific Ocean illustrates that multiple sources contribute to the total Fe budget of the ocean and highlights the importance of oceanic circulation in determining if deeply sourced Fe is ever ventilated at the surface.

scholarly journals EFFECT OF RIP CURRENT BARRIER ON HARBOR SHOALING

1984 ◽  
Vol 1 (19) ◽  
pp. 140 ◽  
Author(s):  
Tamio O. Sasaki ◽  
Hiroshi Sakuramoto
Keyword(s):  
Surf Zone ◽  
Cost Effective ◽  
High Energy ◽  
Rip Current ◽  
Rip Currents ◽  
Effective Measure ◽  
The Pacific ◽  
Small Craft ◽  
The Pacific Ocean ◽  
Cost Effective Measure

Prototype experiments on rip currents and sediment transport around structures were conducted at two fishery harbors on microtidal high energy beaches facing the Pacific Ocean. The purpose of the experiments was to examine the performance and mechanism of rip current barrier structures on harbor shoaling. Based on the results of five experiments, the wave breaker heights during which varied from 1.1 m to 3.0 m, it is concluded that shore-parallel rip current barriers are effective if their length is greater than the surf zone width and if they are located outside the surf zone. When the above conditions are satisfied, the rip current barrier is a cost-effective measure against shoaling of small craft harbors.

Sign in / Sign up

Export Citation Format

Share Document