The Bureau of Meteorology Atmospheric high-resolution Regional Reanalysis for Australia (BARRA) is the first atmospheric regional reanalysis over a large region covering Australia, New Zealand and southeast Asia. The production of the reanalysis with approximately 12 km lateral resolution -BARRA-Ris well underway with completion expected in 2019. 15 This paper describes the numerical weather forecast model, the data assimilation methods, and the forcing and observational data used to produce BARRA-R, and analyses results from the 2007-2016 reanalysis. BARRA-R provides a realistic depiction of the meteorology at and near the surface over land as diagnosed by temperature, wind speed and precipitation. It shows closer agreement with point-scale observations and gridded analysis of observations, than leading global reanalyses. In particular, BARRA-R improves upon ERA-Interim global reanalysis in several areas at point-scale to 25 km resolution. BARRA-R shows 20 reduced negative biases in (point-scale) 10 m wind speed during strong wind periods, reduced biases in (5 km gridded) daily temperature maximum and minimum, and higher frequency of very heavy precipitation days at 5 km and 25 km resolution.Few issues with BARRA-R are also identified; some of which are common in reanalyses, such as biases in 10 m wind, and others that are more specific to BARRA such as grid point storms. Some of these issues could be improved through dynamical downscaling of BARRA-R fields using convective-scale (< 2 km) models. 25
IntroductionReanalyses are widely used for climate monitoring and studying climate change as they provide spatially complete records of the atmosphere for long periods that are a balance between physical consistency and observations. This is achieved by using data assimilation techniques that produce an observation-constrained model estimate of the atmosphere, by drawing short-term model states towards observations from multiple, disparate sources to form an atmospheric analysis. The use of a physically 30 realistic model enables the estimation of unobserved parameters from the limited and irregularly distributed collection of observed parameters.Geosci. Model Dev. Discuss., https://doi.Global-scale reanalyses using global atmospheric circulation models (GCMs) have advanced in quality and quantity during the past two decades (Dee et al., 2014;Hartmann et al., 2013). At present, the available global reanalyses established for the satellite era include the NCEP/NCAR reanalysis at 210 km horizontal resolution (Kalnay et al., 1996), the Japanese 55-year Reanalysis (JRA-55) at 60 km (Ebita et al., 2011), the Modern-Era Retrospective analysis for Research and Applications-2 (MERRA-2) at about 50 km (Gelaro et al., 2017) and the European Centre for Medium Range Weather Forecasts (ECMWF) 5 ReAnalysis Interim (ERA-Interim) at ~79 km (Dee et al., 2011). The latter will be replaced by the new ERA-5 ~31 km reanalysis (Hersbach and Dee, 2016). The global reanalyses have the advantages of providing globally consistent and homo...