Freva and ClimXtreme: a software framework for the evaluation of climate extremes
Authors: Lucio-Eceiza Etor E. , Kadow Christopher , Bergemann Martin , Ramadoss Mahesh , Lewis Brian , Fast Andrej , Grieger Jens , Richling Andy , Kirchner Ingo , Ulbrich Uwe , Thiemann Hannes , Ludwig Thomas 
Published: December 2021

&lt;p&gt;The number of damaging events caused by natural disasters are increasing because of climate change. Projects of public interest such as ClimXtreme (Climate Change and Extreme Events [1, 2]), aim to improve our knowledge of extreme events, the influence of environmental changes and their societal impacts.&lt;/p&gt;
&lt;p&gt;ClimXtreme takes a holistic approach this problem through different knowledge areas. For that, projects like this need a coordinate effort from many interdisciplinary groups. On the other hand, the continuous improvement of numerical models and increase on observational data availability provides researchers with a growing amount of data to analyze, and the need for greater resources to host, access, and evaluate them efficiently through High Performance Computing (HPC) infrastructures is growing more than ever. Finally, the emphasis these last years on FAIR data principles [3] and the easy reproducibility of evaluation workflows also requires a framework that facilitates these tasks. Freva (Free Evaluation System Framework [4, 5]) is an efficient solution to handle customizable evaluation systems of large research projects, institutes or universities in the Earth system community [6-8] over the HPC environment and in a centralized manner.&lt;/p&gt;
&lt;p&gt;Freva is a scientific software infrastructure for standardized data and analysis tools (plugins) that provides all its available features both in a shell and web environment. Written in python, is equipped with a standardized model database, an application-programming interface (API) and a history of evaluations, among others:&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;An implemented metadata system in SOLR with its own search tool allows scientists and their plugins to retrieve the required information from a centralized database. The databrowser interface satisfies the international standards provided by the Earth System Grid Federation (ESGF, e.g. [9]).&lt;/li&gt;
&lt;li&gt;An API allows scientific developers to connect their plugins with the evaluation system independently of the programming language. The connected plugins are able to access from and integrate their results back to the database, allowing for a concatenation of plugins as well. This ecosystem increases the number of scientists involved in the studies, boosting the interchange of results and ideas. It also fosters an active collaboration between plugin developers.&lt;/li&gt;
&lt;li&gt;The history and configuration sub-system stores every analysis performed with Freva in a MySQL database. Analysis configurations and results can be searched and shared among the scientists, offering transparency and reproducibility, and saving CPU hours, I/O, disk space and time.&lt;/li&gt;
&lt;/ul&gt;
&lt;p&gt;The usage of Freva in the context of ongoing large projects like ClimXtreme will be discussed. Additionally, major updates of the software, system deployment, and core functionalities will be presented.&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;&amp;#160;&lt;/strong&gt;&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;References:&lt;/strong&gt;&lt;/p&gt;
&lt;p&gt;[1] https://www.fona.de/de/massnahmen/foerdermassnahmen/climxtreme.php&lt;/p&gt;
&lt;p&gt;[2] https://www.climxtreme.net/index.php/en/&lt;/p&gt;
&lt;p&gt;[3] https://www.go-fair.org/fair-principles/&lt;/p&gt;
&lt;p&gt;[4] Kadow, C. et al. , 2021. Introduction to Freva &amp;#8211; A Free Evaluation System Framework for Earth System Modeling. &lt;em&gt;JORS&lt;/em&gt;. http://doi.org/10.5334/jors.253&lt;/p&gt;
&lt;p&gt;[5] gitlab.dkrz.de/freva&lt;/p&gt;
&lt;p&gt;[6] freva.met.fu-berlin.de&lt;/p&gt;
&lt;p&gt;[7] https://www.xces.dkrz.de/&lt;/p&gt;
&lt;p&gt;[8] www-regiklim.dkrz.de&lt;/p&gt;
&lt;p&gt;[9] https://esgf-data.dkrz.de/projects/esgf-dkrz/&lt;/p&gt;