31 research outputs found
Influence of frontal cyclone evolution on the 2009 (Ekman) and 2010 (Franklin) Loop Current eddy detachment events
The anticyclonic Loop Current Eddy (LCE) shedding events are strongly
associated with the evolution of Loop Current Frontal Eddies (LCFEs) over
the eastern Gulf of Mexico (GoM). A numerical simulation, in tandem with in situ
measurements and satellite data, was used to investigate the Loop Current
(LC) evolution and the surrounding LCFE formation, structure, growth and
migration during the Eddy Ekman and Eddy Franklin shedding events in the
summers of 2009 and 2010, respectively. During both events, northern GoM
LCFEs appeared vertically coherent to at least 1500 m in temperature
observations. They propagated towards the base of the LC, where, together
with the migration of Campeche Bank (southwest GoM shelf) eddies from south
of the LC, contributed to its "necking-down". Growth of Campeche Bank
LCFEs involved in Eddy Franklin was partially attributed to Campeche Bank
waters following upwelling events. Slope processes associated with such
upwelling included offshore exports of high positive potential vorticity
that may trigger cyclone formation and growth. The advection and growth of
LCFEs, originating from the northern and southern GoM, and their interaction
with the LC over the LCE detachment area favor shedding conditions and may
contribute to the final separation of the LCE
Progress in operational modeling in support of oil spill response
Following the 2010 Deepwater Horizon accident of a massive blow-out in the Gulf of Mexico, scientists from government, industry, and academia collaborated to advance oil spill modeling and share best practices in model algorithms, parameterizations, and application protocols. This synergy was greatly enhanced by research funded under the Gulf of Mexico Research Initiative (GoMRI), a 10-year enterprise that allowed unprecedented collection of observations and data products, novel experiments, and international collaborations that focused on the Gulf of Mexico, but resulted in the generation of scientific findings and tools of broader value. Operational oil spill modeling greatly benefited from research during the GoMRI decade. This paper provides a comprehensive synthesis of the related scientific advances, remaining challenges, and future outlook. Two main modeling components are discussed: Ocean circulation and oil spill models, to provide details on all attributes that contribute to the success and limitations of the integrated oil spill forecasts. These forecasts are discussed in tandem with uncertainty factors and methods to mitigate them. The paper focuses on operational aspects of oil spill modeling and forecasting, including examples of international operational center practices, observational needs, communication protocols, and promising new methodologies
Riemannian metrics and Laplacians for generalized smooth distributions
We show that any generalized smooth distribution on a smooth manifold, possibly of non-constant rank, admits a Riemannian metric. Using such a metric, we attach a Laplace operator to any smooth distribution as such. When the underlying manifold is compact, we show that it is essentially self-adjoint. Viewing this Laplacian in the longitudinal pseudodifferential calculus of the smallest singular foliation which includes the distribution, we prove hypoellipticity. © 2021 World Scientific Publishing Company
Evolution of a buoyant outflow in the presence of complex topography: The Dardanelles plume (North Aegean Sea)
The outflow of Waters of Black Sea origin (BSW) through the Dardanelles Strait is the strongest buoyant input for the North Aegean Sea (NAS). Two opposing flows exist across the Dardanelles exit: a lighter, upper layer outflow (BSW) and a denser, deeper layer inflow (waters of Mediterranean origin). This study examines the processes influencing the plume development and evolution. The complex topography of the receiving basin (NAS) plays a significant role on the preferred BSW pathways that are controlled by the buoyancy and wind forcing. A high‐resolution numerical model, the NAS‐HYCOM (Hybrid Coordinate Ocean Model), is implemented to perform process‐oriented experiments that examine the relative role of the forcing factors and topographic effects. Three major pathways are identified. In the absence of wind, an anticyclonic bulge is formed inducing a Westward Jet that is topographically guided between two islands near the outflow. Topography also controls the development of a buoyancy‐driven Coastal Current and a Rim Current along the North Aegean shelf areas. Comparison of model results to analytical calculations suggests that topography modifies the formation and the ballooning of the anticyclonic bulge, which are controlled by the outflow rate, the resulting stratification and Coriolis. Experiments also employ several wind directions and magnitudes in combination with different outflow characteristics. The study elucidates the importance of the Aegean morphology on the processes controlling the coupling to the Black Sea. The BSW are found to influence both deep and shelf Aegean basins, along their overall cyclonic pathway toward the eastern Mediterranean.
Key Points
Black Sea Waters propagation on North Aegean Sea (NAS)
NAS‐HYCOM (Hybrid Coordinate Ocean Model) performs process oriented experiments
Processes influencing the plume development and evolutio
On a Malware Targeting Private Telephony Networks during Cyber Conflict
Telecommunication networks have long ago entered the Critical Infrastructure domain. Apart from the public telephony network, there is a parallel private telephony network, consisting of Private Branch Exchanges (PBXs) that serve the communication needs of private or public entities. Their penetration in the market is substantial. As a result, thousands of PBX installations are present in every country serving many times more users in vital infrastructures (including health, safety, security, economy, energy). Therefore, attacking PBXs can have critical effects that disrupt society and can clearly be used in warlike situations. PBXs are an integral part of the critical infrastructure, along with the public telephony network. The contribution of this work focuses on the theoretical and practical capabilities of a malware able to target PBXs. Such an occurrence would have devastating effects on the communication confidentiality, integrity and availability
Influence of frontal cyclone evolution on the 2009 (Ekman) and 2010 (Franklin) Loop Current eddy detachment events
The anticyclonic Loop Current Eddy (LCE) shedding events are strongly
associated with the evolution of Loop Current Frontal Eddies (LCFEs) over
the eastern Gulf of Mexico (GoM). A numerical simulation, in tandem with in situ
measurements and satellite data, was used to investigate the Loop Current
(LC) evolution and the surrounding LCFE formation, structure, growth and
migration during the Eddy Ekman and Eddy Franklin shedding events in the
summers of 2009 and 2010, respectively. During both events, northern GoM
LCFEs appeared vertically coherent to at least 1500 m in temperature
observations. They propagated towards the base of the LC, where, together
with the migration of Campeche Bank (southwest GoM shelf) eddies from south
of the LC, contributed to its "necking-down". Growth of Campeche Bank
LCFEs involved in Eddy Franklin was partially attributed to Campeche Bank
waters following upwelling events. Slope processes associated with such
upwelling included offshore exports of high positive potential vorticity
that may trigger cyclone formation and growth. The advection and growth of
LCFEs, originating from the northern and southern GoM, and their interaction
with the LC over the LCE detachment area favor shedding conditions and may
contribute to the final separation of the LCE
Influence of frontal cyclones evolution on the 2009 (Ekman) and 2010 (Franklin) Loop Current Eddy detachment events
The anticyclonic Loop Current Eddy (LCE) shedding events are strongly associated with the
evolution of Loop Current Frontal Eddies (LCFEs) over the eastern Gulf of Mexico
(GoM). A numerical simulation, in tandem with in situ measurements and satellite data, was used to
investigate the Loop Current (LC) evolution and the surrounding LCFEs formation, structure, growth
and migration during the Eddy Ekman and Eddy Franklin shedding events in the summers of 2009 and
2010, respectively. During both events, Northern GoM LCFEs appeared vertically coherent to at
least 1500 m in temperature observations. They propagated towards the base of the LC
where, together with the migration of Campeche Bank eddies from south of the LC, contributed
to its "necking down". Growth of Campeche Bank LCFEs involved in Eddy Franklin was partially
attributed to Campeche Bank waters following upwelling events. Slope processes associated with
such upwelling include offshore exports of high positive vorticity that may trigger cyclone
formation and growth. The advection and growth of LCFEs, originating from the northern and
southern GoM, and their interaction with the LC over the LCE detachment area favor shedding
conditions and may lead to the final separation of the LCE
Evidence for Reduced Black Sea Water Outflow to the North Aegean
Abstract The Black Sea Waters (BSW) exported into the Aegean Sea largely control its overturning circulation as well as the regional biogeochemical characteristics. Observational evidence from ARGO floats and satellite‐derived sea surface temperature (SST) and chlorophyll indicate a recent drastic reduction of Black Sea Water presence in the surface layer of the North Aegean Sea. This evidence is also supported by the long‐term negative sea level difference trend between the southwestern Black Sea and the northeastern Aegean Sea. The role of the Black Sea in hindering deep water formation processes in the North Aegean seems to be diminishing. The future evolution of the Aegean overturning cell will depend on whether this trend will continue, in addition to the variability of local atmospheric forcing
Enabling risk assessment and analysis by event detection in dementia patients using a reconfigurable rule set
Chronic mental illnesses pose a great burden on the lives of citizens worldwide. In modern health-care, decentralization and enabling the self management of patients at home are crucial factors in improving the every-day lives of patients and the people close to them. People in general tend to dislike obtrusive monitoring on their daily activities, so how can we implement a platform that can provide clinicians with adequate and concise information on their patients health status and at the same time be unobtrusive and easy to use. Moreover, how can we make such an unobtrusive system capable of providing the doctor with highimpact warnings on the patient's health status only when it is needed, thus relieving him of unnecessary workload? In this paper, the authors present a reconfigurable Event Detection mechanism used in the ALADDIN platform for Risk Assessment and Analysis