Analyses of native water, bottom material, elutriate samples, and dredged material from selected southern Louisiana waterways and selected areas in the Gulf of Mexico, 1979-81

AbstractHurricane Gustav (2008) made landfall in southern Louisiana on 1 September 2008 with its eye never closer than 75 km to New Orleans, but its waves and storm surge threatened to flood the city. Easterly tropical-storm-strength winds impacted the region east of the Mississippi River for 12–15 h, allowing for early surge to develop up to 3.5 m there and enter the river and the city’s navigation canals. During landfall, winds shifted from easterly to southerly, resulting in late surge development and propagation over more than 70 km of marshes on the river’s west bank, over more than 40 km of Caernarvon marsh on the east bank, and into Lake Pontchartrain to the north. Wind waves with estimated significant heights of 15 m developed in the deep Gulf of Mexico but were reduced in size once they reached the continental shelf. The barrier islands further dissipated the waves, and locally generated seas existed behind these effective breaking zones.The hardening and innovative deployment of gauges since Hurricane Katrina (2005) resulted in a wealth of measured data for Gustav. A total of 39 wind wave time histories, 362 water level time histories, and 82 high water marks were available to describe the event. Computational models—including a structured-mesh deepwater wave model (WAM) and a nearshore steady-state wave (STWAVE) model, as well as an unstructured-mesh “simulating waves nearshore” (SWAN) wave model and an advanced circulation (ADCIRC) model—resolve the region with unprecedented levels of detail, with an unstructured mesh spacing of 100–200 m in the wave-breaking zones and 20–50 m in the small-scale channels. Data-assimilated winds were applied using NOAA’s Hurricane Research Division Wind Analysis System (H*Wind) and Interactive Objective Kinematic Analysis (IOKA) procedures. Wave and surge computations from these models are validated comprehensively at the measurement locations ranging from the deep Gulf of Mexico and along the coast to the rivers and floodplains of southern Louisiana and are described and quantified within the context of the evolution of the storm.

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Now & Then: From Manager to Meteorologist From Heavenly Bodies to Barometers

Mathematics Teaching in the Middle School ◽

10.5951/mtms.1.2.0123 ◽

1994 ◽

Vol 1 (2) ◽

pp. 123-129

Author(s):

Sue Barnes ◽

Karen Dee Michalowicz ◽

Melanie A. Womack

Keyword(s):

Gulf Of Mexico ◽

Late Summer ◽

Severe Weather ◽

Television Station ◽

Large Town ◽

Southern Louisiana

Now… Shreveport is a large town in Northwest Louisiana. A state that is classified as a severe-weather area. Northern Louisiana is often hit by thunderstorms and tornadoes. Southern Louisiana, on the Gulf of Mexico, is susceptible to hurricanes during late summer. When the manager of television station KSLA in Shreveport began looking for a person to fill the weather-news slot a few years ago, he did not want someone who could just point to a weather map. He wanted a good meteorologist. In regions that have invariant weather, those people who give the weather are usually actors or actresses who read the predictions prepared by someone else. The study of weather, however, is called meteorology, and a professional meteorologist is someone who has a degree in weather study. Even in area with severeweather conditions, some television stations do not hire a professional meteorologist but hire a broadcast meteorologist instead. A broadcast meteorologist is a journalist who has taken general courses in meteorology while studying for a communications or journalism degree.

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Preliminary results from a shallow water bottom interaction experiment in the Gulf of Mexico

The Journal of the Acoustical Society of America ◽

10.1121/1.2025525 ◽

1988 ◽

Vol 83 (S1) ◽

pp. S79-S79

Author(s):

James F. Lynch ◽

George V. Frisk ◽

Subramaniam D. Rajan

Keyword(s):

Gulf Of Mexico ◽

Shallow Water ◽

Preliminary Results ◽

Interaction Experiment ◽

Water Bottom

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Marine PSSP reflections with a bottom velocity transition zone

Geophysics ◽

10.1190/1.1443180 ◽

1992 ◽

Vol 57 (1) ◽

pp. 161-170 ◽

Cited By ~ 12

Author(s):

N. W. Kim ◽

A. J. Seriff

Keyword(s):

Gulf Of Mexico ◽

Transition Zone ◽

Shear Wave ◽

Wave Reflection ◽

Conversion Factor ◽

Shear Velocity ◽

Data Acquisition System ◽

Theoretical Considerations ◽

Water Bottom ◽

Low Shear

Marine shear‐wave reflection methods using the conventional data acquisition system (i.e., source and receiver in water) rely on two mode conversions at the water bottom to produce shear reflections such as PSSP. Some theoretical considerations and the results of a marine check shot survey conducted in the Gulf of Mexico demonstrate that the difficulty in observing PSSP events is attributable to weak P-S and S-P conversion at the bottom in regions with very low shear velocity (a few hundred ft/s or less) sediments at the bottom. For a simple water bottom with a low shear‐wave velocity, water over a uniform half space, the PS conversion factor is proportional to [Formula: see text] and the SP conversion factor is proportional to [Formula: see text], where [Formula: see text] is the bottom shear velocity. For [Formula: see text] their product gives PSSP reflections that can be comparable in amplitude to typical PPPP events. For [Formula: see text], the PSSP events should be about 30 dB weaker and probably not visible. For typical Gulf of Mexico sediments with a shear velocity transition zone several tens of feet thick at the bottom, the situation is even worse, since the velocities start near zero and may not reach 500 ft/s. This condition is common in many areas of recent sedimentations.

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