Wave, Wind and Current Characteristics of Bay of Campeche

Abstract

Abstract The approach and selected results of a comprehensive study of storm generated waves and associated winds and currents in the southern Gulf of Mexico (Bay of Campeche) are presented in this paper. The study included the hindcast of historical hurricanes as well as winter storms and the statistical analysis of the hindcast data to determine return period estimated of maximum wave heights and associated parameters throughout the OCS of the southern Gulf of Mexico. A detailed description of hurricane Roxanne (1995) (the most severe hurricane that has affected the area during this century) and its impact on the extreme climate descriptions are also presented. Introduction At the beginning of the offshore drilling operations in the Bay of Campeche, platforms and pipelines were designed using rough estimates of the meteorological and oceanographic (metocean) conditions of this area due to the lack of measurements. Several punctual studies based on Bretschneider's techniques were carried out to establish metocean design conditions for specific sites where most of the platforms were to be located. By November 1993 a definitive study of meteorological and oceanographic normal and extreme conditions in the eastern Bay of Campeche based on application of modem hindcast models was performed1 followed by a measurement program in water depths of 150 and 300 m. Although the measurement program lasted only about one year, it was fully operational during the passage of hurricane Gert, and provided data which served to validate the hindcast methodology. In October 1995, hurricane Roxanne, which formed and became a Category 3 storm in the western Caribbean Sea, crossed the Yucatan Peninsula and then entered the Bay of Campeche. Roxanne meandered there for several days causing severe destruction along the coast of Mexico and significant damage to PEMEX's offshore infrastructure. Little scientific measurement systems were in place in the Bay of Campeche during the storm, so a hindcast was performed to assess the forces responsible for the observed damage and to revisit the extremal analysis to update the rare return period design data2. In the next section, we describe hurricane Roxanne, the results of its hindcast and its rank relative to the results of the November, 1993 study. This is followed by a description of the update design study carried out during 1996 to define extreme and normal conditions throughout Bay of Campeche. Hurricane Roxanne Storm History. Fig 1 shows the storm track. Roxanne passed westward across Yucatán and emerged over the Bay of Campeche on October 12 in a considerably weakened state with central pressure of 990 mb. Further weakening occurred in the following 24 hours after which the center turned toward the northwest and slowly strengthened. A cold front followed by a large high pressure system (1027 mb) moved across the US Gulf Coast states on the 13th and 14th, and these extratropical systems evidently forced Roxanne to turn south and execute a clockwise loop during October 15 and 16. At the beginning of this loop, Roxanne reached again hurricane intensity and during the southward leg of this loop, Roxanne intensified to 979 mb with maximum sustained (1-minute) winds of about 70 knots (130 km/h).