The Gulf of Mexico circulation is modulated by a mesoscale current, the Loop Current (LC), and large anticyclonic eddies that detach from it. The LC dynamics are recurrent, and its evolution is in and from a few preferential states. This observation points to the existence of a low‐dimensional dynamical attractor. Building upon advancements in dynamical system theory, this work characterizes the average and instantaneous dimensions of such an attractor. The instantaneous dimension and its evolution in time are compared among an altimeter‐based data set, an ocean reanalysis and an operational hindcast. The LC complexity, measured by its dimension, differs among them, especially when the dimension is high. During shedding events, differences between datasets emerge in the second principal component. The information provided by this analysis is relevant to operational ocean forecasts and points to where improvement should occur.

No abstract

The degree of connectivity among populations influences their ability to respond to natural and anthropogenic stressors. In marine systems, determining the scale, rate, and directionality of larval dispersal is therefore central to understanding how coral metapopulations are interconnected and the degree of resiliency in the event of a localized disturbance. Understanding these source-sink dynamics is essential to guide restoration efforts and for the study of ecology and evolution in the ocean. The patterns and mechanisms of connectivity in the deep-sea (> 200 meters deep) are largely understudied. In this study, we investigated the spatial diversity patterns and metapopulation connectivity of the octocoral Paramuricea biscaya throughout the northern Gulf of Mexico (GoM). Paramuricea biscaya is one of the most abundant corals on the lower continental slope (between 1200 and 2500 m) in the GoM. The 2010 Deepwater Horizon oil spill (DWH) directly impacted populations of this species and thus are considered primary targets for restoration. We used a combination of seascape genomic analyses, high-resolution ocean circulation modeling, and larval dispersal simulations to quantify the degree of population structuring and connectivity among P. biscaya populations. Evidence supports the hypotheses that the genetic diversity of P. biscaya is predominantly structured by depth, and that larval dispersal among connected populations is asymmetric due to dominant ocean circulation patterns. Our results suggest that there are intermediate unsampled populations in the central GoM that serve as stepping stones for dispersal. The data suggest that the DeSoto Canyon area, and possibly the West Florida Escarpment, critically act as sources of larvae for areas impacted by the DWH oil spill in the Mississippi Canyon. This work illustrates that the management of deep-sea marine protected areas should incorporate knowledge of connectivity networks and depth-dependent processes throughout the water column.

Abstract--We investigate network management information for light-path assessment to dynamically set up end-to-end lightpaths across administrative domains. Our focus is on invetigating what performance can be possibly achieved given partial management information, and whether a small loss in performance can trade off with a large saving in management information.The partial information we consider includes aggregated characterization of subnetworks, and local states from wavelength converters. We cast the light-path assessment as a decision problem, and define the performance as the probability of an erroneous decision. We apply the decision theory to show that the optimal performance using the partial information is the Bayes probability of error. We derive an upper bound of the Bayes error in terms of the blocking probability. We evaluate the upper bound using both independent and dependent models of wavelength usage. Our study shows that there exits a ``threshold effect'': The Bayes error decreases exponentially to 0 with respect to the load when the load is either below or above a threshold value; and is non-negligible when the load is in a small duration around the threshold. This suggests that a small percentage of error decisions can trade off with a large saving in management information.Index terms--Partial management information, lightpath assessment, decision theory, Bayes rule, blocking probability. I. INTRODUCTIONDynamically assessing the quality of light-paths is important to many applications in wavelength-routed optical networks such as on-demand light-path provisioning, protection and restoration. As the light-path quality is a complex measure [1], this work considers a simple quality, which is the wavelength availability on a candidate light-path. The assessment then becomes determining availability of wavelengths for supporting an end-to-end call based on given management information.Complete or partial network management information can be used to assess the wavelength availability on a light-path. Complete information corresponds to the detailed states of wavelength usage, i.e. "which wavelengths are used at which links of a network'', when there is no wavelengths converters in the network. Wavelength converters can reduce state information due to their ability to relax the wavelength continuity constraint. However, it is expected that wavelength converters remain expensive and are thus used mostly on the boundaries of sub-networks [2]. Therefore, generally complete state information involves the detailed wavelength occupancy within a subnet. Partial information includes aggregated load and topology information at each subnet, and local states, e.g., the total number of wavelengths used at wavelength converters.Providing state information is a basic functionality of network management. Traditional network management systems intend to obtain as complete state information as possible [3]. But future IP-WDM networks may have hundreds of links with each link supporting hundreds of wavelengths [...