The Spatial and Temporal Variability of the Northwestern Gulf of Mexico
Team: Erica Pinkney and Danielle Graves
Mentor: Dr. Sonia Gallegos and Dr. Malcolm LeCompte
Undergraduate Research Experience in Ocean and Marine Science
Elizabeth City State University (CERSER Lab)
ABSTRACT
A pilot study was undertaken to determine the spatial and temporal variability of chlorophyll concentrations in the northwestern Gulf of Mexico during 2002. The chlorophyll parameter was obtained from daily Level-3 estimations of Sea-Viewing Wide-Field-of–view Sensor (SeaWiFS) data computed by the Naval Research Laboratory. An empirical eigenfunction (EOF) analysis was performed on the data using the Karhunen-Loeve (KL) algorithm. Ten empirical eigenfunctions, temporal coefficients, and variance spectrum were computed. This analysis revealed that 15% of the variance around the mean is accounted by the first empirical eigenfunction, which is identified with chlorophyll fluctuations around the Mississippi Delta, Lakes Pontchartrain and Borgne, the Mississippi Sound, and the Mobile, Pensacola, and Choctawhatchee Bays. The eigenfunction shows that the chlorophyll in near-shore water is changing more rapidly than the rest of the shelf waters. The second EOF which contained 3% of the variance is found to be related to changes in chlorophyll in bays and estuaries to the east of the delta, exclusively. The third EOF (%) was identified with the waters flowing east from the mouth of the Mississippi into bays and estuaries. The fourth EOF (%) is identified with changes in chlorophyll concentrations at the mouth of the Mississippi River proper, propitiated by the river flow. Because this EOF is also identified with waters of Lakes Pontchartrain and Borgne as well as with the Mississippi Sound, it is possible that the changes observed may not be related to chlorophyll but to increases in dissolved and particulate components brought about by an increase in rain fall.
