首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Hydrography and frontogenesis in a glacial fjord off the Strait of Magellan
Authors:Arnoldo Valle-Levinson  José Luis Blanco  Máximo Frangópulos
Institution:(1) Civil and Coastal Engineering Department, University of Florida, 365 Weil Hall, FL 32611-6580 Gainesville, USA;(2) Code 614, Observational Science Branch, NASA Wallops Flight Facility, Rm. E226, Bldg. N-159, VA 23337 Wallops Island, USA;(3) Centro de Estudios del Cuaternario Fuego-Patagonia (CEQUA), Instituto de Fomento Pesquero, Punta Arenas, Chile
Abstract:Current velocity and hydrographic profiles obtained for the first time in a Chilean glacial fjord were combined with under-way surface temperature and salinity measurements to describe the formation of tidal intrusion fronts and plume-like fronts. These fronts formed within several hundred meters from each other in the vicinity of a shallow sill, maximum depth of approximately 3 m, in a glacial fjord off the Strait of Magellan in the Chilean Patagonia. Measurements were obtained in mid-December of 2003 and 2004, during late austral spring, under active glacier melting and calving. The glacial fjord is approximately 18 km long from the face of the glacier to the connection with the Strait of Magellan and typically less than 1 km wide throughout the system. Between the glacier face and the 3-m sill, depths are typically less than 100 m, and seaward of the sill, depths increase to more than 200 m. Velocity and salinity data obtained during flood periods revealed that water with oceanic salinity was aspirated to near-surface levels from depths of approximately 30 m as flood flows accelerated from approximately 10 cm s−1, seaward of the sill, to approximately 60 cm s−1 at the sill crest. The upwelled water was then slightly diluted by mixing at the sill crest before plunging down to the basin between the glacier and the sill. The plunging of salty water over the sill created dramatic tidal intrusion fronts only a few tens of meters from the sill crest and pumping of salt with every flood period. During ebb periods, the low salinity waters derived from the glacier and a small river near the glacier converged at the sill crest. After some mixing, the buoyant waters were released within a thin layer (∼3 m deep) lead by a plume-like front that remained coherent for a few hundred meters seaward of the sill. The main findings of this study were that tidal intrusion and plume fronts were observed within 2 km from each other, and that tidal pumping was the predominant mechanism for salt fluxes into the system.
Keywords:
本文献已被 SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号