OSU Tidal Inversion Software

The OSU Tidal Inversion Software (OTIS) is a relocatable implementation of the tidal data inversion scheme described in [Egbert, Benett, Foreman, 1994], further developed in [Egbert and Erofeeva, 2002]

All our global/regional/local barotropic tidal models were developed using OTIS.


If you need tide predictions at some locations/times you probably do NOT need to create your own tidal model from scratch. You can use the existing models plus OTPS. You need OTIS only if you have high quality and high-resolution local bathymetry and/or substantial volume of data to assimilate for your desired domain. Then, perhaps you have a chance to utilize OTIS for obtaining a better quality local solution compared to already existing models and thus get better tidal predictions.


- Significant RAM for matrix factorization. The actual RAM size depends on your inverse problem dimensions; for relatively small sample Red Sea problem, included with OTIS, 11GB of RAM is required.

- Software: a Fortran compiler, LAPACK and BLAS libraries, MATLAB

- Significant additional disk space for storing intermediate results of computations, depending on your inverse problem dimensions.

- A barotropic tidal model, which includes your local domain, for open boundary conditions and as a correction model, i.e. global TPXO. It can be any barotropic tidal model, but it should be in OTIS binary multi-constituent (not-atlas) format.

- Bathymetry data, extracted for your domain from existing sources, such as SRTM15, GEBCO, etc.

- Tidal data for inversion: measurements coming from satellite altimetry, tide gauges, current meters etc.

All our models and software are under the same license:

COPYRIGHT Egbert & Erofeeva, OSU, 2010

OTIS is available for academic research and other non-commercial uses and requires registration. To register for OTIS, please send to Dr. Erofeeva and/or Prof. Egbert request including:

  1. Your name
  2. Your institution
  3. Detail explanation on intended OTIS use.

To refer to OTIS in your publications please use the citation:

Egbert, Gary D., and Svetlana Y. Erofeeva. "Efficient inverse modeling of barotropic ocean tides." Journal of Atmospheric and Oceanic Technology 19.2 (2002): 183-204.

We do not provide complimentary OTIS consulting/support. Please address OTIS manual.