The pressure-invariant neutral density variable (Lang et al., 2020) which uses SCV (submesoscle coherent vortices) methods to connect the observation bottle with the reference data.
Neutral density based on Jackett and McDougall (1997), which uses the NTP (Neutral Tangent Plane) to connect the observation bottle with the reference data.
In the absence of irreversible mixing, fluid parcels in the ocean move such that they are always at their level of neutral buoyancy with their environment. This constrains the flow such that infinitesimal displacements lie in a plane, called the neutral tangent plane. This plane is well-defined at every point in the ocean. A neutral surface is an extensive 2D surface that is everywhere aligned with the neutral tangent plane (McDougall 1987). However, neutral surfaces are not well-defined 2D surfaces -- a consequence of the non-linear equation of state for the density of seawater, and the resulting non-zero neutral helicity in the ocean (McDougall and Jackett 1988). Hence, physical oceanographers craft approximately neutral surfaces (ANSs), which are well-defined extensive 2D surfaces that are everywhere approximately aligned with the neutral tangent plane. The following approximately neutral surfaces may be calculated with this software package.
Omega surfaces (Klocker et al., 2009; Stanley et al. 2021) are highly accurate approximately neutral surfaces, formed from an iterative procedure that solves a global least squares problem to minimize the neutrality error.
The ANS that minimizes the slope error.
The ANS that minimizes the fictitious diapyncal diffusivity.
The ANS that minimizes the spurious diasurface velocity.
The ANS that minimizes the spurious diasurface velocity times the veritial gradient of the temperature.
The ANS that minimizes the spurious diasurface velocity times the veritial gradient of the salinity.
The ANS that minimizes a combination of those quantities minimized by Omega_u.s and Omega_s^2.
./gamma/- create gamma^SCV neutral density variables./lib_add/- libraries./run/- example scripts./omega-surface/- create omega series of surfaces./README.md- this fileneutral-surfaces. In MATLAB, check that which omega_surface succeeds.addpath(genpath(<<The path to this repository>>)), modifying the path as necessary.Klocker, A., McDougall, T.J., Jackett, D.R., 2009. A new method for forming approximately neutral surfaces. Ocean Science 5, 155–172. https://doi.org/10.5194/os-5-155-2009
Lang, Y., Stanley, G. J., McDougall, T. J., & Barker, P. M. (2020). A pressure-invariant neutral density variable for the world's oceans. Journal of Physical Oceanography, 50(12), 3585-3604.
Lang, Y., Stanley, G. J., & McDougall, T. J., (2023). Spurious dianeutral advection and methods for its minimization. Journal of Physical Oceanography.
McDougall, T.J., 1987. Neutral Surfaces. Journal of Physical Oceanography. https://doi.org/10.1175/1520-0485(1987)017<1950:NS>2.0.CO;2
McDougall, T.J., Jackett, D.R., 1988. On the helical nature of neutral trajectories in the ocean. Progress in Oceanography 20, 153–183. https://doi.org/10.1016/0079-6611(88)90001-8
Montgomery, R., 1937. A suggested method for representing gradient flow in isentropic surfaces. Bull. Amer. Meteor. Soc 18, 210–212.
Stanley, G.J., 2019a. Neutral surface topology. Ocean Modelling 138, 88–106. https://doi.org/10.1016/j.ocemod.2019.01.008
Stanley, G. J., McDougall, T. J., & Barker, P. M. (2021). Algorithmic improvements to finding approximately neutral surfaces. Journal of Advances in Modeling Earth Systems, 13, e2020MS002436. https://doi.org/10.1029/2020MS002436
Wüst, G., 1935. The stratosphere of the Atlantic ocean. Scientific Results of the German Atlantic Expedition of the Research Vessel “Meteor” 1925–27 6.
MIT License
Copyright (c) 2023 Yandong Lang, Geoff Stanley, and Trevor McDougall
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Author(s) : Yandong Lang and Geoff Stanley
Email : yandong.lang@unsw.edu.au; gstanley@uvic.ca
Email : aaronlangyandong@gmail.com; geoffstanley@gmail.com