Exponential leap-forward gradient scheme for determining the isothermal layer depth from profile data
MetadataShow full item record
Two distinct layers usually exist in the upper ocean. The rst has a near-zero vertical gradient in temperature (or density) from the surface and is called the iso-thermal layer (or mixed layer). Beneath that is a layer with a strong vertical gradient in temperature (or density), called the thermocline (or pycnocline). The isothermal layer depth (ILD) or mixed layer depth (MLD) for the same pro le var- ies depending on the method used to determine it. Also, whether they are subjective or objective, existing methods of determining the ILD do not estimate the thermocline (pycnocline) gradient. Here, we propose a new exponen- tial leap-forward gradient (ELG) method of determining the ILD that retains the strengths of subjective (simplicity) and objective (gradient change) methods and avoids their weaknesses (subjective methods are threshold-sensitive and objective methods are computationally intensive). This new method involves two steps: (1) the estimation of the ther- mocline gradient Gth for an individual temperature pro le, and (2) the computation of the vertical gradient by averag- ing over gradients using exponential leap-forward steps. Such averaging can lter out noise in the pro le data. Five existing methods of determining the ILD (difference, gra- dient, maximum curvature, maximum angle, and optimal linear tting methods) as well as the proposed ELG method were veri ed using global expendable bathythermograph (XBT) temperature and conductivity–temperature–depth (CTD) datasets. Among all the methods considered, the ELG method yielded the highest skill score and the lowest Shannon information entropy (i.e., the lowest uncertainty).
The article of record as published may be found at http://dx.doi.org/10.1007/s10872-017-0418-0.
RightsThis publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
Showing items related by title, author, creator and subject.
Evaluation of daytime boundary layer heights from a mesoscale model using profilers/RASS measurements Bloch, Lindsay A. (Monterey, California. Naval Postgraduate School, 2008-03);This thesis study focuses on the evaluation of the boundary layer height (BLH) diagnosed from a mesoscale model in comparison to wind profiler/Radio Acoustic Sounding System (RASS) measurements from the profiler site at ...
Sadagic, Amela; Darken, Rudolph P. (North Atlantic Treaty Organization, 2006-06-01);It is clear that the way the military prepares for combat is rapidly changing. Doctrine and mission objectives are changing at a faster rate than ever before. The operational tempo is faster than it has been in the past. ...
Scorgie, Mark A.; Sanders, Richard D. (Monterey, California. Naval Postgraduate School, 2002-03);The purpose behind this thesis was two-fold. First, the effect of sound delivery on a user's sense of presence in a virtual environment was investigated. Second, the physiological responses of electrodermal activity, heart ...