last modified Mar 05, 2018 03:09 PM
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CMIP-compliant processing

Motivation

Climate data to be published within CMIP6 must meet a quality standard that allows a systematic analysis of the data across models and experiments. The application of the CMOR library developed at PCMDI ensures that its output data complies with the project standard. The program rewrites model data in various model output formats in a compliant way and saves it in a NetCDF file, one variable per file. The dataset is provided with all necessary and suitable metadata.

Because the CMOR application involves invoking various program functions which require the provision of extensive information about the input data, inexperienced users need a long training period or processing time. In oder to support national CMIP6 participants in using the CMOR library, it will be integrated into the worldwide accepted and widely used CDO package. A new operator 'cmor' is developed that provides the experienced CDO user with a common look&feel, and the support infrastructure which is built around the CDO toolkit. By using the information obtained from the interface of CDO about the metadata of the input file, the information that has to be provided by the user can be reduced to a minimum.

Development and Objectives

Building on the experience and tools of previous CMIP phases, a CDO operator was developed that uses the CMOR2 software to create CMIP5 compliant data. This operator version has been further developed, so that current versions of the CMOR3 library can also be linked to the CDO toolkit enabling the production of CMIP6 compliant data. In the long term, the operator should be able to create the standard of further CMIP phases as well as other projects. The operator should accept as input data the raw output data of current Earth system models.

Another goal is to achieve that CDO operators process - as far as possible - in a CMIP6 compliant way. In order to reach this goal, the CDO (meta) data model is being adapted to the CMIP standard. The main focus is on the preservation of CMIP-compliant attributes and coordinate names. In addition, the data model of the CDOs will be extended so that it can recognize previously unknown data structures. A recent example is a 'character coordinate' whose coordinate values are of the data type 'CHRACTER'.