ARA

Starting point / motivation

Reanalysis products have proven themselves as an important resource and have contributed positively to improving our understanding of Earth’s system. They have also been employed in various projects aimed at climate monitoring and assessment of climate change impacts.

Contents and goals

The ARA project aims at creating first of its kind high resolution (2.5 km) reanalysis ensemble dataset for Austria. Once completed it will provide a detailed (2D and 3D) information on the state of atmosphere in Austria from 2010 – 2020. Successful completion of this prototype has the potential to further develop into a viable operational / commercial product.

Methods

It will provide essential climate variables (ECVs) at spatial and temporal scales relevant for the NWP (numerical weather prediction)/ climate research community and can be further exploited by impact research to improve resilience in the community by strengthening mitigation and adaption efforts. This reanalysis can become a useful addition to national and international climate services, e.g. national OKS25 dataset and Copernicus Climate Change Service (C3S)

ARA is primarily based on dynamical downscaling of European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 dataset (with a spatial resolution of 31km) by applying "Application of Research to Operations at Mesoscale" (AROME) non-hydrostatic limited area model to a destination spatial resolution of 2.5km. With the aid of the three-dimensional variational assimilation (3DVAR) system in AROME and the Convection-permitting Limited Area Ensemble Forecasting system (C-LAEF), observations from multiple sources, such as, satellites, radiosondes, aircraft, wind profiler etc. will be assimilated to reconstruct a ten member ensemble with spatially, temporally, and physically consistent 3D and 2D atmospheric fields.

In addition to enhanced spatial resolution this reanalysis will provide ECVs that will be aggregated at hourly, sub-daily, daily, and monthly scale. It is also planned to provide an uncertainty estimate from the ensemble which will be made publicly available. The application potential for such a dataset is enormous.

Expected results

In order to limit the scope of this project we have proposed two use cases. That is, 

1. evaluation / validation of NWP and climate models at convection permitting scale and
2. calculation of extreme forecast index (EFI).

Moreover, there are additional benefits stemming from long term climate simulation as they can be used as a reference to validate operational forecast, creating extreme forecast index and to calibrate the AROME based forecasting systems. Similar activities at the European scale have shown great promise and have left a considerable impact in the research arena as these projects have proven to be useful beyond the scope of the project.

The idea of high resolution regional reanalysis ensemble for Austria has also been met with great enthusiasm and attached LOIs show that this project has the potential to leave its mark and ensure the leading role of applicant and project partner at national and international stage.

Coordinator

University of Graz

University of Graz
Dr. Heimo Truhetz
Brandhofgasse 5/1. Stock
A-8010 Graz