Coastal Upwelling of Magdalena Bay, Mexico, in a La Niña year

Abstract

[Author's abstract]Upwelling off Magdalena Bay on the west coast of Baja Mexico was investigated and the magnitude of upwelling calculated. From March 20-21st the R/V Thomas G. Thompson cruised from the coast north of Magdalena Bay toward the southern tip of Baja. Two transects bounded the coast in order to calculate the volume of water transported off shore (Figure 1). The Magdalena Bay area was chosen due to consistent upwelling in the area caused by favorable shore orientation, winds, and bathymetry (Figure 4). Water velocity was recorded using the ship’s Acoustic Doppler Current Profiler (ADCP). Satellite and Conductivity-Temperature-Depth (CTD) data was used to find the common signatures of upwelling; lower sea surface temperature and shallower thermocline structure. Anomalously cool water along the equator, caused by La Nina, can reinforce winds and increase upwelling in the area. Higher than predicted coastal upwelling may have been caused by a tongue of cold water in the study area. This cold tongue may have increased the water transport out of the study area. Upwelling is responsible for high productivity along the California Current System (CCS). It is believed that increased upwelling can enhance productivity and produce a net sink of CO2 in upwelling regions.