APS2-ACCESS-C2: the first Australian operational NWP convection-permitting model

The Australian Bureau of Meteorology’s ‘Australian Parallel Suite’ (APS) operational numerical weather prediction regional Australian Community Climate and Earth-System Simulator (ACCESS) city-based system (APS1 ACCESS-C1) was updated in August 2017 with the com-missioning of the APS2 ACCESS-C2. ACCESS-C2 runs over six regional domains. Significant upgrade changes included implementation of Unified Model 8.2 code; nesting in the 12 km resolution APS2 ACCESS-R2 regional model; and, importantly, an increased horizontal resolution from 4 to 1.5 km, enabling C2 to become the first Australian operational convection-permitting model (CPM). Traditional rainfall verification metrics and Fractions Skill Score show C2 forecast skill over ACCESS-C domains in summer and winter was generally, and in many cases, significantly better than C1. Case studies showed that C2 forecasts had better-detailed wind and precipitation fields, particularly at longer forecast ranges and higher rain rates. The improvements in C2 forecasts were principally due to its CPM ability to simulate high temporal and spatial resolution features, which continue to be of great interest to forecasters. C2 also laid the groundwork for the present day APS3 ACCESS-C forecast C3 and ensemble CE3 models and further development of higher resolution (down to 300 m) fire weather and urban models.

[1]  L. Rikus,et al.  Impact of Doppler Radar Wind Observations on Australian High-Resolution Numerical Weather Prediction , 2020 .

[2]  R. Smalley,et al.  An enhanced gridded rainfall analysis scheme for Australia , 2020 .

[3]  João Bosco Coura dos Reis,et al.  Validation of Satellite Rainfall Products over a Mountainous Watershed in a Humid Subtropical Climate Region of Brazil , 2017, Remote. Sens..

[4]  Richard Swinbank,et al.  The Met Office convective‐scale ensemble, MOGREPS‐UK , 2017 .

[5]  R. Laprise,et al.  Spatial spin-up of fine scales in a regional climate model simulation driven by low-resolution boundary conditions , 2017, Climate Dynamics.

[6]  Peter Clark,et al.  Convection‐permitting models: a step‐change in rainfall forecasting , 2016 .

[7]  W. Tennant.  Improving initial condition perturbations for MOGREPS‐UK , 2015 .

[8]  R. Leung,et al.  A review on regional convection‐permitting climate modeling: Demonstrations, prospects, and challenges , 2015, Reviews of geophysics.

[9]  G. Huffman,et al.  Integrated Multi-satellitE Retrievals for GPM (IMERG) Technical Documentation , 2015 .

[10]  T. Davies.  Lateral boundary conditions for limited area models , 2014 .

[11]  Richard G. Forbes,et al.  The evolution of an MCS over southern England. Part 2: Model simulations and sensitivity to microphysics , 2014 .

[12]  H. Lean,et al.  The benefits of the Met Office variable resolution NWP model for forecasting convection , 2013 .

[13]  Marion Mittermaier,et al.  A long‐term assessment of precipitation forecast skill using the Fractions Skill Score , 2013 .

[14]  Flora J. Logan-Klumpler,et al.  Implementation of the initial ACCESS numerical weather prediction system , 2013 .

[15]  P. Nolan,et al.  Reducing errors of wind speed forecasts by an optimal combination of post‐processing methods , 2013 .

[16]  P. Friederichs,et al.  Spatial kinetic energy spectra in the convection-permitting limited-area NWP model COSMO-DE , 2012 .

[17]  D. Karoly,et al.  Non-stationarity in daily and sub-daily intense rainfall – Part 2: Regional assessment for sites in south-east Australia , 2011 .

[18]  F. Mesinger.  Bias Adjusted Precipitation Threat Scores , 2008 .

[19]  N. Roberts,et al.  Scale-Selective Verification of Rainfall Accumulations from High-Resolution Forecasts of Convective Events , 2008 .

[20]  S. Chumchean,et al.  Rainfields: The Australian Bureau of Meteorology System for Quantitative Precipitation Estimation, and It's Use in Hydrological Modelling , 2007 .

[21]  W. Skamarock.  Evaluating Mesoscale NWP Models Using Kinetic Energy Spectra , 2004 .

[22]  J. Wyngaard,et al.  Resolution Requirements for the Simulation of Deep Moist Convection , 2003 .

[23]  J. McBride,et al.  Verification of Quantitative Precipitation Forecasts from Operational Numerical Weather Prediction Models over Australia , 2000 .