West Florida Shelf Upwelling: Origins and Pathways

Often described as oligotrophic, the west Florida continental shelf supports abundant fisheries, experiences blooms of the harmful alga, Karenia brevis, and exhibits subsurface chlorophyll maxima evident in shipboard and glider surveys. Renewal of inorganic nutrients by the upwelling of deeper ocean water onto the shelf may account for this, but what are the origins and pathways by which such new water may broach the shelf break and advance toward the shoreline? We address these questions via numerical model simulations of pseudo-Lagrangian, isopycnic water parcel trajectories. Focus is on 2010, when the west Florida shelf was subjected to an anomalously protracted period of upwelling caused by Gulf of Mexico Loop Current interactions with the shelf slope. Origins and pathways are determined by integrating trajectories over successive 45 day intervals, beginning from different locations along the shelf break and at various locations and depths along the shelf slope. Waters upwelling across the shelf break are found to originate from relatively shallow depths along the shelf slope. Even for the anomalous 2010 year, much of this upwelling occurs from about 150 m and above, although waters may broach the shelf break from 300 m depth, particularly in the Florida Panhandle. Such interannual renewal of west Florida shelf waters appears to have profound effects on west Florida shelf ecology

On the Movement of Deepwater Horizon Oil to Northern Gulf Beaches

Surface oil of Deepwater Horizon origin sullied the northern Gulf of Mexico marshes and beaches from Louisiana to Florida. The Mississippi to Florida beaches were particularly impacted during the month of June 2010. We review the evolution of the surface oil as it approached the beach and then consider the mechanisms of transport. Both the ocean circulation and ocean waves are found to be important. The circulation appears to control the transport of surface oil in deep waters and over most of the continental shelf. But as oil approaches shallow water the wave orientation may become more conducive than the circulation orientation for transporting oil to the beach. In essence it is found that the circulation gets the oil to the vicinity of the beach, whereas the waves, via Stokes drift, are responsible for the actual beaching of oil. A combination of observations and numerical model simulations are used to demonstrate this

Combining Numerical Ocean Circulation Models with Satellite Observations in a Trajectory Forecast System: a Rapid Response to the Deepwater Horizon Oil Spill

The Deepwater Horizon oil spill presented an unprecedented threat to the Gulf of Mexico coastline and living marine resources, and possibly to that of the southeastern USA. Needed for mitigation efforts and to guide scientific investigations was a system for tracking the oil, both at the surface and at depth. We report on such system, implemented immediately upon spill onset, by marshaling numerical model and satellite remote sensing resources available from existing coastal ocean observing activities. Surface oil locations inferred from satellite imagery were used to initialize the positions of the virtual particles in an ensemble of trajectory models, and the particles were tracked using forecast surface currents, with new particles added to simulate the continual release of oil from the well. Three dimensional subsurface tracking were also performed from the well site location at several different depths. Timely trajectory forecasts were used to plan scientific surveys and other spill response activities

Dysfunction in interhemispheric inhibition and enhancement in patients with schizophrenia

背景此前有研究结果表明精神分裂症患者大脑左右两半球之间的协同功能下降；但临床神经心理研究结果提示大脑两半球的协同活动有互抑与互补两种形式。本研究旨在进一步探讨精神分裂症患者的大脑两半球互抑与互补两种协同功能是否均受损。方法30例精神分裂症患者和28名健康对照纳入研究，采用Stroop字图实验和注意广度实验分别测试大脑两半球的互抑及互补协同功能，用三视野速示法将图形伪随机呈现在左、中、右视野。实验中被试眼睛与电脑屏幕正中注视点保持水平，距离屏幕的距离为57cm。左、右侧视野的图形位置为水平距离正中点3°～6°视角，中间视野图形的位置为正中左右各1．5°视角，所有图形距离屏幕正中水平线上下各1．5°视角。①Stroop字图实验的图形为直径30mm的圆形或边长30mm的正方形，内有一个汉字“方”或“圆”。每次图形呈现的时间为66．7ms，要求被试又快又准地用按鼠标键的方式判断图形是圆形还是方形，计算机自动记录被试在每个图形判断上的正确与否以及反应时。②注意广度实验的图形是边长26mm的方框内散布着2～9个直径1．4mm的黑圆点，每次图形呈现的时间为130ms。要求被试报告图形中黑点的数目，由主试记录被试每次报告的结果。用斯皮尔曼分配法计算每个被试各个视野的注意广度。结果①Stroop字图实验：所有被试字图不一致图形的反应时长于字图一致图形（P〈0．001），中视野错误率高于左视野（P〈0．05）。患者组中视野错误率高于对照组（P〈0．05）。②注意广度实验：所有被试左、右视野的注意广度为中视野的1／2。患者组中视野注意广度较对照组差（P〈0．01），患者组大脑两半球互补协同功能及左半球的协同能力比正常组差（P〈0．05）。结论精神分裂症患者大脑两半球互抑及互补协同功能均受损，患者左半球的互补协同能力下降

The Tampa Bay Coastal Ocean Model Performance for Hurricane Irma

The Tampa Bay response to Hurricane Irma in September 2017 is analyzed using a combination of in situ observations and numerical model simulations. The observations include winds and water levels from in situ recording stations. The model simulations are by the Tampa Bay Coastal Ocean Model (TBCOM), which downscales from the continental shelf to the estuary by nesting the unstructured grid, Finite-Volume, primitive equation Community Ocean Model (FVCOM) in the West Florida Coastal Ocean Model, which in turn downscales from the deep ocean across the continental shelf by nesting FVCOM in the Gulf of Mexico Hybrid Coordinate Ocean Model. Both the observations and the model simulations show a rapid negative storm surge (a setdown of sea level) followed by a positive surge associated with the change of wind direction. The initial forecast underestimates the magnitude of the negative surge. After adjusting for the difference between the winds actually observed compared with the original forecast winds, the hindcast sea level simulation very closely matches the observations. These findings imply that a massive exchange of water occurred between Tampa Bay and the adjacent continental shelf as the hurricane passed by the region. A large portion of the bay water was flushed out to the south, to be replaced by new waters advected in from the along the coast to the north

Tracking the Deepwater Horizon Oil Spill: a Modeling Perspective

The Deepwater Horizon oil spill was caused by a drilling rig explosion on 20 April 2010 that killed 11 people. It was the largest oil spill in U.S. history and presented an unprecedented threat to Gulf of Mexico marine resources. Although oil gushing to the surface diminished after the well was capped, on 15 July 2010, much remains to be known about the oil and the dispersants beneath the surface, including their trajectories and effects on marine life. A system for tracking the oil, both at the surface and at depth, was needed for mitigation efforts and ship survey guidance. Such a system was implemented immediately after the spill by marshaling numerical model and satellite remote sensing resources available from existing coastal ocean observing activities [e.g., Weisberg et al., 2009]. Analyzing this system\u27s various strengths and weaknesses can help further improve similar systems designed for other emergency responses

Winds on the West Florida Shelf: Regional Comparisons between Observations and Model Estimates

Wind fields on the West Florida Continental Shelf are investigated using observations from five University of South Florida Coastal Ocean Monitoring and Prediction System buoys and seven of NOAA\u27s National Ocean Service and National Weather Service, National Data Buoy Center stations or buoys spanning the 10 year period, 2004–2013. These observations are compared with NOAA\u27s National Center for Environmental Prediction (NCEP) reanalysis wind fields (NCEP winds). The analyses consist of vector correlations in both the time and frequency domains. The primary findings are that winds observed on and near the coastline underestimate those observed offshore and that NCEP winds derived from assimilating mostly land-based observations also underestimate winds observed offshore. With regard to wind stress, and depending upon location, wind stress derived from NCEP winds are 6%–49% lower than what is computed from observations over open water. A corollary is that wind forcing fields that are underestimated may result in coastal ocean model circulation fields that are also underestimated. These analyses stress the importance of having offshore wind observations, and suggest that adding more offshore wind observations will lead to improved coastal ocean wind fields and hence to improved model renditions of coastal ocean model circulation and related water property fields

Comparisons of Different Ensemble Schemes for Glider Data Assimilation on West Florida Shelf

An Ensemble Optimal Interpolation (EnOI) system is built to assimilate underwater profiling glider observations into a West Florida Shelf (WFS) coastal ocean model. The Floating Temporal Window (FTW) technique is incorporated into the EnOI scheme to generate and update associated ensemble members, which are directly extracted from the model output states from previous output cycles. The model performance is validated against independent observations from moorings located near the glider tracks. The EnKF, traditional EnOI and the FTW-EnOI schemes are compared in terms of error covariance evolution and model performance at mooring locations. It is found that all three assimilation schemes provide significant (2-3 times) better fit to the mooring data compared with the free model run. Although the EnKF scheme produces the best results, the FTW-EnOI should be considered as an alternative method given the low computational cost and the flow-dependent information embedded in the algorithm