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OMP Analysis Package for MATLAB
Version 2.0

Johannes Karstensen
GEOMAR Helmholtz centre for Ocean Research Kiel
RD: Ocean Circulation and Climate Dynamics
Duesternbrooker Weg 20
24105 Kiel
email: jkarstensen(AT)
phone: +49 - 431 - 600 4156
fax: + 49 - 431 - 600 4102

Matthias Tomczak
FIAMS, Flinders University
GPO Box 2100
Adelaide SA 5001
phone: + 61 8 8201 2298

August 1999


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:

phone: + 49 431 600 4156
fax +61 8 8201 2976
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 (101418) 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. 101617184679).

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.


Johannes Karstensen
Matthias Tomczak
August 1999