SLS - Joleen Heiderich
The Gulf Stream: Along-stream evolution of volume transport and modification of water properties observed by underwater gliders
The Gulf Stream is the western boundary current ofthe subtropical North Atlantic and plays a key role in the Earth’s climate system, with its poleward volume and heat transports formingthe upper limb of the Atlantic Meridional Overturning Circulation. Extensive observations collected using Spray autonomous underwater gliders from 2004 tothe present fill a 1,500-km-long gap in longer-term sustained subsurface measurements of the Gulf Stream. The gliders provide concurrent, high-resolution measurements of hydrography and velocity in and near the Gulf Stream over more than 15 degrees of latitude between Florida and New England. These observations are used to characterize the along-stream evolution of Gulf Stream volume transport. The long-known increase in poleward volume transport between the FloridaStrait and the open North Atlantic downstream of Cape Hatteras is shown to result primarily from entrainment of subthermocline waters, including subtropical mode waters (e.g., Eighteen Degree Water) and upper Labrador Sea Water. Antarctic Intermediate Water, which makes up the deepest waters within the Gulf Stream in the Florida Strait, is shown to be eroded away as the current flows northward along the continental margin. Glider observations are used to estimatefluxes through the faces of a control volume in order to elucidate the roles of vertical mixing and lateral fluxes in eroding the Antarctic Intermediate Water.Satellite-based observations of sea surface height coincident with the glider observations are used to evaluate the efficacy of inferring Gulf Stream transport from remotely sensed measurements.Thedetailed analyses of Gulf Stream transport and water property evolution herein provide targets for regional and global circulation models to replicate.
About this Series
The Atmosphere, Ocean and Climate Sack Lunch Seminar Series is an informal seminar series within PAOC that focuses on more specialized topics than the PAOC Colloquium. Seminar topics include all research concerning the science of atmosphere, ocean and climate. The seminars usually take place on Wednesdays from 12-1pm in 54-915. The presentations are either given by an invited speaker or by a member of PAOC and can focus on new research or discussion of a paper of particular interest.