OMP Analysis Package for MATLAB
Institut fuer Meereskunde
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The knowledge of exact mixing fractions of water masses in the ocean
is necessary for various applications, especially in the analysis of transient
tracer fields or biogeochemical cycling. The distribution of tracers is
controlled by a combination of transport processes associated with the
oceanic circulation and mixing and by reactive processes associated with
the major biogeochemical cycles (3).
To evaluate the distribution of nutrients and tracers in the sea one
has to resolve effects of mixing and of biogeochemical cycling. OMP analysis
is a tool to analyse the water mass mixture in a water sample by calculating the contributions from the original water masses (so called source water masses) to the sample.
The program package described in this manual is version 2.0 of an easy-to-use suite of Matlab routines to perform OMP analysis. Because the package is under constant development we ask you to inform us if you are using it and to join the OMP User Group for receiving update and bug reports:
Water mass analysis was introduced by Jacobsen (5) in 1927 as a graphical method to determine mixing coefficients in a temperature-salinity (T/S) diagram and extended in 1935 by Wüst (19), who developed his "core-layer"
method as a tool for studying the oceanic circulation. An extension
of T/S diagram techniques followed in the 1980s when Tomczak (15) introduced Multiparameter Analysis by adding oxygen and nutrients as additional quasi-conservative parameters, assuming that biogeochemical changes of these parameters are neglibible. Several investigators
(10; 14; 18) developed this idea further into an overdetermined problem now known as Optimum Multiparameter (OMP) analysis.
OMP analysis is capable of resolving water mass mixing on regional scales and has become a standard
tool in oceanography. Several applications have successfully analysed
water mass structures with OMP analysis (e.g. 10; 16; 17; 18; 4; 6; 7; 9).
This manual is structured as follows: After a short excursion into OMP
analysis theory, the Matlab routines and their use are described. This is followed by a detailed description of the format required for data input. To assist with the first use of OMP analysis, the package comes with a
test dataset from the Indian Ocean and a step-by-step description of its use in running the programs.