Jeudi 21 janvier - Observing the variability of the oxygen minimum zone off south central Chile
de 11:00 à 12:00
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University of Concepcion, Chile
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Department of Geophysics and Millennium Institute of Oceanography, University of Concepcion, Chile
Title : Observing the variability of the oxygen minimum zone off south central Chile
In contrast to the legendary upwelling that is present along the Peruvian and northern Chilean coasts, the coastal ocean off central Chile presents a highly seasonal upwelling regime that extends from early spring to mid fall. This region presents waters with very low dissolved oxygen conforming the southern tip of the eastern South Pacific oxygen minimum zone(OMZ). Coastal waters are highly productive due to upwelling, but the upwelled source waters may produce hypoxia over the continental shelf. The spatial structure and main scales of variability of the upwelling cells and dissolved oxygen near the coast are poorly understood off central Chile. One of the main limitations has been the lack of direct information. During the last years an observational program has been conducted over the relatively wide continental shelf off Concepción (36°30' S). This program has included ship-based (monthly) time-series, underwater glider observations and time-series based on moored sensors. Additionally, the cross-shelf structure of the upwelling region has been sampled in different period of the year using underwater gliders, capable of sampling the entire water column to a maximum of 1000 m and from near shore to 200 km offshore. Here, based on this information we analyze the main scales of variability of the upwelling and their impact on the dissolved oxygen in this region.