Overview of OCMW tools

OCWM is a library of tools that collates and consolidates our workflow for coastal model development, post-processing, and analysis. The modelling work was targeted at high-energy site characterisation for tidal energy developers, and ran across a number of research projects. The numerical simulations where carried out using the Open Telemac-Mascaret solver, so there is a focus on tools for interrogating output from this model. However, the concepts and methods can be transferred to the output from any numerical solver.

The library of tools has been developed in layers, with the core tools providing generic functions that are independent of any modelling system. From these core functions, modules related to each section of the workflow (domain definition, model design, Cal/Val, data processing, and data management ) have been constructed, providing functions specific to the workflow application. From these workflow modules a set of executable applications have been written to provide tools for automated processing of model data, and a set of example scripts created to show how the tools can be used to characterise a site based on model data, and to validate a model against in situ and remotely sensed data.

Internal Standardization

The are two levels of standardization used in the construction of the OCMW tools.

1. Model data directory structure

2. Standard internal OCMW data formats and structure

The use of a stardardized model directory structure simplifies the automation of OCMW processes by removing the requirement to identify all directories explicitly. Using a standardized directory structure means that only the model root directory needs to be explicitly defined. The use of a standardized internal data format simplifies the passing of information between the OCMW processes.

Model Directory Structure

The model directory structure used for Open Telemac-Mascaret simulations takes the form:

MODEL                  ( Simulation root directory )
│
├───DESIGN             ( Mesh generation scripts, project files and data )
│   ├───bathy
│   ├───bluekenue
│   ├───qgis
│   └───shapefiles
├───TIDEATLAS          ( Tidal atlas used to force the model )
├───GEO                ( OTM geometry and boundary conditons files )
├───RUNLOGS            ( Log files generated for individual model runs )
├───RESTART            ( Restart files used for sequential model runs )
│
├───RESULTS            ( Simulation output files )
│
├───EXTRACT            ( OCMW data extraction files )
├───ANALYSIS           ( OCMW data analysis results )
├───VELOCITY           ( OCMW extracted 2-D velocity field data )
└───IMAGES             ( OCMW generated graphics )

The essential sub-directory used by the OCMW tools to access simulation data is MODEL\RESULTS. This contains the simulation output files; if using another numerical solver the output must be placed in a \RESULTS sub-directory to be compatible with the OCMW tools. The OCMW processing tools automatically generate the \EXTRACT, \ANALYSIS, \VELOCITY and \IMAGES sub-directories in the same root directory as the \RESULTS sub-directory.

The other directories are specific to the construction and running of the Open Telemac-Mascaret simulations. The other main advantage of using a standardized directory structure is that it retains all the information related to the model in a suitable form for archiving.

OCMW Internal Data Format

To simplify the passing of data between OCMW processes, a standard internal data format has been used with a set of standard variable names for common parameters. For simplicity the internal data structure is currently a python data dictionary. This was intially chosen as it allowed the data to be save in Matlab format *.mat files simplifying the sharing of data with user not familiar with python. It became embedded as the tools were developed over a number of years. If needed the format can be changed as the code is structured so that data are loaded and saved using the functions load_comw_data and save_ocmw_data which can be replaced. The implementation is not yet completely generic, so there is ongoing work to refactor the code for consistencies.

Some of the standard internal variables are described in Table 1.

Table 1 : Standard OCMW internal variables.

Variable	Description
dataSrc	String stating where data are from
dataSet	String identifying specific dataset being used
dataLoc	Location coordinates
crs	Coordinate Reference System for location coordinates
times	Timestamps in days from a given epoch
epoch	Epoch string used for timestamps - format “yyyy-mm-dd hh:mm:ss”
depth	Water depth in metres
depAvg_U	Depth averaged U component of horizontal velocities
depAvg_V	Depth averaged V component of horizontal velocites
hab	Height above bed
zLoc	Vertical z location for data
vel_east	Eastward component of velocity in geospatial coordinates
vel_north	Northward component of velocity in geospatial coordinates
vel_up	Vertical component of velocity in geospatial coordinates