Structure and evolution of the central Gulf of Mexico continental margin and coastal plain, southeast United States

2004 ◽  
Vol 116 (1) ◽  
pp. 188 ◽  
Author(s):  
D.L. Harry ◽  
J. Londono
Keyword(s):  
United States ◽  
Gulf Of Mexico ◽  
Continental Margin ◽  
Coastal Plain ◽  
Southeast United States

scholarly journals Mechanisms for Springtime Onset of Isolated Precipitation across the Southeastern United States

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 213
Author(s):  
Rosana Nieto Ferreira ◽  
Thomas M. Rickenbach
Keyword(s):  
United States ◽  
Gulf Of Mexico ◽  
Convective Available Potential Energy ◽  
Warm Season ◽  
Jet Stream ◽  
Southeast United States ◽  
North Atlantic Subtropical High ◽  
The North ◽  
Poleward Shift ◽  
Slow Moving

This study uses four-year radar-based precipitation organization and reanalysis datasets to study the mechanisms that lead to the abrupt springtime onset of precipitation associated with isolated storms in the Southeast United States (SE US). Although the SE US receives relatively constant precipitation year-round, previous work demonstrated a “hidden” summertime maximum in isolated precipitation features (IPF) whose annual cycle resembles that of monsoon climates in the subtropics. In the SE US, IPF rain abruptly ramps up in May and lasts until sometime between late August and early October. This study suggests that the onset of the IPF season in the SE US is brought about by a combination of slow thermodynamic processes and fast dynamic triggers, as follows. First, in the weeks prior to IPF onset, a gradual seasonal build-up of convective available potential energy (CAPE) occurs in the Gulf of Mexico. Then, in one-to-two pentads prior to onset, the upper-tropospheric jet stream shifts northward, favoring the presence of slow-moving frontal systems in the SE US. This poleward shift in the jet stream location in turn allows the establishment of the North Atlantic subtropical high western ridge over the SE US which, with associated poleward transport of high CAPE air from the Gulf of Mexico, leads to the establishment of the warm-season regime of IPF precipitation in the SE US.

scholarly journals Regional variations in the structure of the crust in the central United States from P-wave spectra

1973 ◽  
Vol 63 (5) ◽  
pp. 1663-1687
Author(s):  
Tuneto Kurita
Keyword(s):  
United States ◽  
Gulf Of Mexico ◽  
Crustal Structure ◽  
Coastal Plain ◽  
Lower Crust ◽  
P Wave ◽  
Ratio Method ◽  
Gulf Coastal Plain ◽  
Regional Variations ◽  
Central United States

abstract Regional variations in the crustal structure in the central United States have been inferred by the transfer ratio method from an analysis of long-period P waves recorded at SHA, OXF, FLO and MDS, the stations nearly along 89°W longitude. The crustal structure in this region is approximated by a stack of horizontal parallel layers except possibly in the area around FLO, where the structure is rather complicated. The crustal thickness is predominantly controlled by the thick silicic upper crust, whereas the mafic lower crust is about 10 km thick throughout this region. The P-wave velocity of the lower crust is about 6.9 to 7.0 km/sec except probably in the area around FLO, where 7.4 km/sec velocity is more likely. A sedimentary layer with a velocity of about 3.0 km/sec, having a thickness of about 3 km near the coast of the Gulf of Mexico, tapers out to the north within the Gulf Coastal Plain. Deep discontinuities in the crust may be replaced by transitional layers up to 10 km thick. The Moho is about 33 km deep near the coast of the Gulf of Mexico, deepens to about 41 km near an intersection of the Gulf coastal plain and the interior plain, reaches about 47 km or more in the midst of the interior plain, and rises to about 41 km toward an intersection of the interior plain and the superior upland. As for the midst of the interior plain, however, the depth of the Moho reduces by as much as 5 km, if the velocity in the lower crust is about 7.0 km/sec instead of about 7.4 km/sec. In any case, the general trend of the depth of the Moho may match with the topographic feature from the Gulf of Mexico to Lake Superior.

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