Lozier M. Susan

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Last Name
Lozier
First Name
M. Susan
ORCID
0000-0003-4129-6349

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  • Article
    Estimating the predictability of an oceanic time series using linear and nonlinear methods
    (American Geophysical Union, 2004-08-03) Yuan, Guo-Cheng ; Lozier, M. Susan ; Pratt, Lawrence J. ; Jones, C. K. R. T. ; Helfrich, Karl R.
    This study establishes a series of tests to examine the relative utility of nonlinear time series analysis for oceanic data. The performance of linear autoregressive models and nonlinear delay coordinate embedding methods are compared for three numerical and two observational data sets. The two observational data sets are (1) an hourly near-bottom pressure time series from the South Atlantic Bight and (2) an hourly current-meter time series from the Middle Atlantic Bight (MAB). The nonlinear methods give significantly better predictions than the linear methods when the underlying dynamics have low dimensionality. When the dimensionality is high, the utility of nonlinear methods is limited by the length and quality of the time series. On the application side we mainly focus on the MAB data set. We find that the slope velocities are much less predictable than shelf velocities. Predictability on the slope after several hours is no better than the statistical mean. On the other hand, significant predictability of shelf velocities can be obtained for up to at least 12 hours.
  • Article
    The CLIMODE field campaign : observing the cycle of convection and restratification over the Gulf Stream
    (American Meteorological Society, 2009-09) Marshall, John C. ; Ferrari, Raffaele ; Forget, Gael ; Andersson, A. ; Bates, Nicholas R. ; Dewar, William K. ; Doney, Scott C. ; Fratantoni, David M. ; Joyce, Terrence M. ; Straneo, Fiamma ; Toole, John M. ; Weller, Robert A. ; Edson, James B. ; Gregg, M. C. ; Kelly, Kathryn A. ; Lozier, M. Susan ; Palter, Jaime B. ; Lumpkin, Rick ; Samelson, Roger M. ; Skyllingstad, Eric D. ; Silverthorne, Katherine E. ; Talley, Lynne D. ; Thomas, Leif N.
    A major oceanographic field experiment is described, which is designed to observe, quantify, and understand the creation and dispersal of weakly stratified fluid known as “mode water” in the region of the Gulf Stream. Formed in the wintertime by convection driven by the most intense air–sea fluxes observed anywhere over the globe, the role of mode waters in the general circulation of the subtropical gyre and its biogeo-chemical cycles is also addressed. The experiment is known as the CLIVAR Mode Water Dynamic Experiment (CLIMODE). Here we review the scientific objectives of the experiment and present some preliminary results.
  • Article
    Slope water, Gulf Stream, and seasonal influences on southern Mid-Atlantic Bight circulation during the fall-winter transition
    (American Geophysical Union, 2005-02-16) Rasmussen, Linda L. ; Gawarkiewicz, Glen G. ; Owens, W. Brechner ; Lozier, M. Susan
    Observations from autumn, 2000, near the shelfbreak front in the Middle Atlantic Bight are used to describe the transition from stratified summer conditions to well-mixed winter conditions over the shelf. During the observational period, the front differed dramatically from climatological conditions, with buoyant Gulf Stream water found shoreward over the sub-surface shelfbreak front. Water mass analysis shows a large number of separate water masses with shelf, slope and Gulf Stream origins. The coolest shelf water was located at the shelfbreak and may be related to “cold pool” water masses observed to the north during summer. Shoreward of this shelfbreak water mass, a mid-shelf front was present which intersected the bottom at the 50 m isobath. High volume transports were associated with both the shelfbreak and mid-shelf fronts. Transport estimates from the cross-shelf sections were approximately 1 Sverdrup, which is large relative to previous estimates of shelf transport. The foot of the front was near the 130 m isobath, much deeper than the climatological position near the 75 m isobath, however this is consistent with a recent theory relating the magnitude of alongshelf transport to the depth at which the front intersects the bottom.
  • Article
    How does Labrador Sea Water enter the deep western boundary current?
    (American Meteorological Society, 2008-05) Palter, Jaime B. ; Lozier, M. Susan ; Law, Kara L.
    Labrador Sea Water (LSW), a dense water mass formed by convection in the subpolar North Atlantic, is an important constituent of the meridional overturning circulation. Understanding how the water mass enters the deep western boundary current (DWBC), one of the primary pathways by which it exits the subpolar gyre, can shed light on the continuity between climate conditions in the formation region and their downstream signal. Using the trajectories of (profiling) autonomous Lagrangian circulation explorer [(P)ALACE] floats, operating between 1996 and 2002, three processes are evaluated for their role in the entry of Labrador Sea Water in the DWBC: 1) LSW is formed directly in the DWBC, 2) eddies flux LSW laterally from the interior Labrador Sea to the DWBC, and 3) a horizontally divergent mean flow advects LSW from the interior to the DWBC. A comparison of the heat flux associated with each of these three mechanisms suggests that all three contribute to the transformation of the boundary current as it transits the Labrador Sea. The formation of LSW directly in the DWBC and the eddy heat flux between the interior Labrador Sea and the DWBC may play leading roles in setting the interannual variability of the exported water mass.