Suchergebnisse

IV Encuentro Oceanografía Física Española, celebrado del 20 al 22 de julio de 2016 en Alicante,España.-- 1 page, 1 figure ; Maps of velocity vectors and streamlines, calculated after integration from some reference contour, can be very useful to illustrate the gross characteristics of the changing velocities. Nevertheless, they are only snapshots of the velocity field that cannot be used to directly infer exchange between different oceanic regions. In order to do so, we must use of a Lagrangian approach, where we actually track water parcels as they move under the influence of the spatially and temporally changing velocity fields. Here we present a simple model that integrates monthly velocity fields in time, either forward or backward, in order to track the origin or fate of water parcels. In our case, the velocity fields are inferred from the positions of Argo floats. We illustrate the model by examining the recirculation of intermediate waters in the southern South Atlantic Ocean. The model allows us tracking whether and how the water parcels at these intermediate depths recirculate zonally or drift meridionally. In this application, we carefully explore the important role of the Brazil-Malvinas Confluence and the Agulhas Leakage. We estimate that most of the intermediate waters recirculate across the ocean in time periods between about 15 and 30 years, eventually meeting at the Brazil-Malvinas Confluence region. Our results show no water transfer from the Indian Ocean, i.e. they show no Agulhas Leakage, although this may be an artefact caused by the absence of rings in the mean fields. A remarkable feature is the presence of a meridionally pulsating behaviour in the transoceanic trajectories, best visible in an accompanying video ; This research has been supported by the Ministerio de Economía y Competitividad of the Spanish Government through project VA-DE-RETRO (CTM2014-56987-P) ; Peer Reviewed

IV Encuentro Oceanografía Física Española, celebrado del 20 al 22 de julio de 2016 en Alicante,España.-- 1 page, 1 figure ; Since 2007, in the world's oceans there are over 3000 Argo floats that transmit position data typically once every 10 days. This represents some 100.000 positions yearly that lead to an equivalent number of velocity vectors. This massive amount of velocity data allows us constructing monthly-mean fields with spatial resolution of the order of 1º in latitude-longitude. Here we present, for the first time, the monthly sea-surface velocity fields for all oceans, unravelling the spatial distribution of the seasonally evolving fields. The velocity fields are predominantly zonal except for the western boundary subtropical regions. Further, these zonal fields change spatially following the evolution of the Intertropical Convergence Zone and the accompanying low- and high-pressure centres in both hemispheres. The resulting patterns appear as a transoceanic meridional seasonal pulse, typically propagating from south to north and from east to west. This work illustrates the potential of the Argo-inferred velocity data for an improved description of the surface currents at regional and, most remarkably, global scales ; This research has been supported by the Ministerio de Economía y Competitividad of the Spanish Government through project VA-DE-RETRO (CTM2014-56987-P) ; Peer Reviewed

5 pages, 4 figures ; We use Argo float trajectories to infer ocean current velocity at the sea surface and 1000 dbar near Australia. The East Australian Current flows southward along the east coast of Australia at both surface and intermediate levels, but only the intermediate waters leak round the southern tip of Tasmania and cross the Great Australian Bight. We calculate the transport of Antarctic Intermediate Water (AAIW) between the southern Australian coast and the Antarctic Circumpolar Current (ACC) as the velocity at 1000 dbar times the layer thickness. Between March 2006 and December 2012, the Eulerian AAIW transport through 147°E ranges between 0 and 12.0 sverdrup (Sv). The mean Tasman Leakage of intermediate waters from the Pacific Ocean into the Indian Ocean, obtained using all Argo data until March 2013, is 3.8 ± 1.3 Sv. The mean intermediate water transport into the Indian Ocean through 115°E increases to 5.2 ± 1.8 Sv due to contributions from the westward recirculation of ACC waters. Keypoints An estimate of the Tasman Leakage, with error bars, is obtained A description of mean and seasonal velocity fields near Australia is provided Argo float data are used to calculate velocity vectors and water transports ©2013. American Geophysical Union. All Rights Reserved ; Funding for this work comes from the Spanish Ministerio de Ciencia e Innovación through project "Tipping Corners in the Meridional Overturning Circulation" (TIC-MOC, reference CTM2011-28867). Miquel Rosell-Fieschi would also like to acknowledge the Ministerio de Ciencia e Innovación for funding through a FPU grant. This work was supported in part by the Australian Government's Cooperative Research Centres Program, through the Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC), and by the Department of Climate Change and Energy Efficiency, through the Australian Climate Change Science Program ; Peer Reviewed