Introduction to OpenDA
OpenDA is a generic environment for data-assimilation tasks like parameter calibration and measurement filtering. It provides a platform that allows an easy interchange of algorithms and models.
It is a modular framework, containing methods and tools that can be used for a wide range of applications. By offering the data-assimilation software as a separate component, the cost of applying data-assimilation methods in one’s project is reduced. At the same time, it allows new developments in the field of data assimilation to quickly spread to all applications that might benefit from it. A short introduction to data assimilation can be found here.
OpenDA is configured using XML
files (Extensible Markup Language
files), in which the information about the data-assimilation components
is specified. For instance, if you would like to use a different
calibration algorithm or stochastic observer, or if you would like to
couple your own model to OpenDA, you should provide all necessary
settings, file names, variable names, etc. to OpenDA in XML input files.
The format of the XML files is specified in XML schema
.xsd) that are
hosted on the OpenDA schemas
The diagrams describing the format of the XML schemas can be found using
an XML visualisation tool.
In general, the user needs to provide one main configuration file and several configuration files describing each data-assimilation component. The main configuration file contains references to the other components’ configuration files. Usually, there are three main data-assimilation components: stochastic model, stochastic observer, and algorithm. In addition, another component may be specified to configure how OpenDA output will be stored.
In OpenDA, the following configuration files are used:
Main configuration file (with XML schema
openDaApplication.xsd): In the main configuration file, the OpenDA java class names, working directories and configuration file names of all the used data-assimilation components are specified.
Stochastic observer: In this configuration file, the user specifies the observation data used in the application as well as the information about its uncertainty.
Stochastic model: In this configuration file, the user specifies the model-related information.
Algorithm: In this configuration file, the user specifies the input parameters required by the data-assimilation or parameter-calibration algorithm being used.