U.S. GLOBEC: GEORGES BANK PHASE III Cross-Frontal Exchange Studies at the Base of the Tidally Mixed Front using an Injected Dye Tracer

点击翻译按钮获取中文摘要

U.S. GLOBEC: GEORGES BANK PHASE III Cross-frontal exchange studies at the base of the tidally mixed front using an injected dye tracerRobert W. Houghton Georges Bank is surrounded by a tidally mixed front. The role of this front in maintaining the high biological productivity on the Bank (Is it a barrier or conduit?) is not fully understood. There is evidence that cross-frontal circulation may be critical for modulating the flux of nutrients and the retention of particles, such as zooplankton and fish larvae, on the Bank both of which contributes to the high productivity of this ecosystem. We propose to use a purposefully injected dye to directly measure the mixing and cross-bank circulation at the foot of the tidal front where on-bank flux is expected to be greatest. The utility of a fluorescent dye tracer for such studies has recently been demonstrated at the shelfbreak front on the New England Shelf. The ability of the dye to follow a constantly moving frontal boundary makes it a particularly powerful technique for studies on Georges Bank. Since the spreading of the dye patch is referenced to the temperature field that defines the front, the complexity introduced by frontal displacements, irregular bottom topography, and a fluctuating, strong along-bank flow is avoided and the cross-frontal circulation and mixing is unambiguously defined. The dye tracer measurements will contribute directly to our understanding of the processes that make Georges Bank such a highly productive marine ecosystem. This understanding is necessary in order to manage this resource to maintain and exploit its optimum contribution to the nation's economy. The understanding is also necessary to anticipate how changes in the forcing of this ecosystem by potential climate changes will affect this, and other, valuable marine resources. This project by demonstrating the unique utility of the dye tracer will advance the development of this technology for future applications in marine research.