Bower Amy S.

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Amy S.

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  • Article
    The scientific and societal uses of global measurements of subsurface velocity
    (Frontiers Media, 2019-07-24) Szuts, Zoltan B. ; Bower, Amy S. ; Donohue, Kathleen A. ; Girton, James B. ; Hummon, Julia M. ; Katsumata, Katsuro ; Lumpkin, Rick ; Ortner, Peter B. ; Phillips, Helen E. ; Rossby, H. Thomas ; Shay, Lynn Keith ; Sun, Charles ; Todd, Robert E.
    Ocean velocity defines ocean circulation, yet the available observations of subsurface velocity are under-utilized by society. The first step to address these concerns is to improve visibility of and access to existing measurements, which include acoustic sampling from ships, subsurface float drifts, and measurements from autonomous vehicles. While multiple programs provide data publicly, the present difficulty in finding, understanding, and using these data hinder broader use by managers, the public, and other scientists. Creating links from centralized national archives to project specific websites is an easy but important way to improve data discoverability and access. A further step is to archive data in centralized databases, which increases usage by providing a common framework for disparate measurements. This requires consistent data standards and processing protocols for all types of velocity measurements. Central dissemination will also simplify the creation of derived products tailored to end user goals. Eventually, this common framework will aid managers and scientists in identifying regions that need more sampling and in identifying methods to fulfill those demands. Existing technologies are capable of improving spatial and temporal sampling, such as using ships of opportunity or from autonomous platforms like gliders, profiling floats, or Lagrangian floats. Future technological advances are needed to fill sampling gaps and increase data coverage.
  • Technical Report
    Boundary current experiment I & II, RAFOS float data report, 1994-1997
    (Woods Hole Oceanographic Institution, 1998-03) Hunt, Heather D. ; Bower, Amy S.
    This is the final data report of all RAFOS (acoustically tracked) float data collected during the 1994-1997 Boundary Current Experiment (BOUNCE) study of the Deep Western Boundary Current (DWBC) in the North Atlantic Ocean. The overall objective of the program was to obtain the first comprehensive description of the North Atlantic DWBC's variability over a large path segment from Cape Hatteras to the Grand Banks. The experiment was comprised of CTD, tracer, and RAFOS float observations to achieve both Eulerian and Lagrangian descriptions of the DWBC. The three main objectives of the Lagrangian float study were 1) to determine fluid parcel pathways in the DWBC and identify regions of exchange with the interior, 2) to estimate the mean speed and variabilty of fluid parcels at two different levels in the DWBC, and 3) to study the kinematics and potential vorticity dynamics of fluid parcels in the DWBC at the Gulf Stream cross-over point near Cape Hatteras. Thirty floats were deployed: 15 were designed to be isopycnal floats, and 15 were isobaric floats. The isopycnal floats were ballasted for the 0, = 27.73 density surface (approximately 800 decibars (db)) to seed the Upper Labrador Sea Water. The isobaric floats were ballasted for 3000 db to seed the Nordic Seas overflow water.
  • Technical Report
    Warm water pathways in the northeastern North Atlantic ACCE RAFOS float data report November 1996 - November 1999
    (Woods Hole Oceanographic Institution, 2001-11) Furey, Heather H. ; Bower, Amy S. ; Richardson, Philip L.
    This is the final data report of all acoustically tracked RAFOS float data collected by the Woods Hole Oceanographic Institution in 1996-1999 during the Atlantic Climate Change Experiment (ACCE). The RAFOS float component of ACCE, entitled "Warm Water Pathways and Intergyre Exchange in the Northeastern North Atlantic," was designed to measure the warm water currents entering the northeastern North Atlantic which become the source of intermediate and deep waters in the subpolar region. The experiment was comprised of three RAFOS float deployments on the R/V Knorr: the first in fall 1996 along the continental slope seaward of Porcupine Bank, the second in spring 1997 along the mid-Atlantic Ridge, and the final deployment in fall 1997 along both the Ridge and the Bank. Seventy floats were deployed, 13 RAFOS and 2 ALFOS in fall 1996, 14 RAFOS in spring 1997, and 41 RAFOS in fall 1997. The isobaric ALFOS floats were ballasted for 800 decibars and were launched to monitor the regions' sound sources during the experiment. The RAFOS floats were isopycnal and ballasted for the 27.5 sigma-t surface to target the intermediate-depth North Atlantic and Poleward Eastern Boundary Currents. The objectives of the Lagrangian float study were (1) to provide a quantitative description of the bifurcation of the North Atlantic Current east of the Mid-Atlantic Ridge, (2) to assess the importance of meridional eddy fluxes, compared to large-scale advection, in the northward flux of heat and salt in the northeastern North Atlantic, and (3) to establish the degree of continuity of the Poleward Eastern Boundary Current as it flows to the entrance of the Norwegian Sea and the fate of the Mediterranean Outflow Water carried by this current.
  • Technical Report
    A Mediterranean undercurrent seeding experiment (AMUSE) : part II: RAFOS float data report, May 1993-March 1995
    (Woods Hole Oceanographic Institution, 1998-06) Hunt, Heather D. ; Wooding, Christine M. ; Chandler, Cynthia L. ; Bower, Amy S.
    This is the final data report of all acoustically tracked RAFOS data collected in 1993-1995 during A Mediterranean Undercurrent Seeding Experiment (AMUSE). The overall objective of the program was to observe directly the spreading pathways by which Mediterranean Water enters the North Atlantic. This includes the direct observation of Mediterranean eddies (meddies), which is one mechanism that transports Mediterranean Water to the North Atlantic. The experiment was comprised of a repeated high-resolution expendable bathythermograph (XBT) section and RAFOS float deployments across the Mediterranean Undercurrent south of Portugal near 8.5°W. A total of 49 floats were deployed at a rate of about two floats per week on 23 cruises on the chartered Portuguese-based vessel, Kialoa II, and one cruise on the R/V Endeavor. The floats were ballasted for 1100 or 1200 decibars (db) to seed the lower salinity core of the Mediterranean Undercurrent. The objectives of the Lagrangian float study were (1) to identify where meddies form, (2) to make the first direct estimate of meddy formation frequency, (3) to estimate the fraction of time meddies are being formed, and (4) to determine the pathways by which Mediterranean Water which is not trapped in meddies enters the North Atlantic.
  • Article
    Lagrangian views of the pathways of the Atlantic meridional overturning circulation
    (American Geophysical Union, 2019-07-19) Bower, Amy S. ; Lozier, M. Susan ; Biastoch, Arne ; Drouin, Kimberley L. ; Foukal, Nicholas P. ; Furey, Heather H. ; Lankhorst, Matthias ; Rühs, Siren ; Zou, Sijia
    The Lagrangian method—where current location and intensity are determined by tracking the movement of flow along its path—is the oldest technique for measuring the ocean circulation. For centuries, mariners used compilations of ship drift data to map out the location and intensity of surface currents along major shipping routes of the global ocean. In the mid‐20th century, technological advances in electronic navigation allowed oceanographers to continuously track freely drifting surface buoys throughout the ice‐free oceans and begin to construct basin‐scale, and eventually global‐scale, maps of the surface circulation. At about the same time, development of acoustic methods to track neutrally buoyant floats below the surface led to important new discoveries regarding the deep circulation. Since then, Lagrangian observing and modeling techniques have been used to explore the structure of the general circulation and its variability throughout the global ocean, but especially in the Atlantic Ocean. In this review, Lagrangian studies that focus on pathways of the upper and lower limbs of the Atlantic Meridional Overturning Circulation (AMOC), both observational and numerical, have been gathered together to illustrate aspects of the AMOC that are uniquely captured by this technique. These include the importance of horizontal recirculation gyres and interior (as opposed to boundary) pathways, the connectivity (or lack thereof) of the AMOC across latitudes, and the role of mesoscale eddies in some regions as the primary AMOC transport mechanism. There remain vast areas of the deep ocean where there are no direct observations of the pathways of the AMOC.