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Journal of Southern Hemisphere Earth Systems Science Journal of Southern Hemisphere Earth Systems Science SocietyJournal of Southern Hemisphere Earth Systems Science Society
A journal for meteorology, climate, oceanography, hydrology and space weather focused on the southern hemisphere
RESEARCH ARTICLE (Open Access)

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

Greg Roff https://orcid.org/0000-0002-8428-3153 A * , Ilia Bermous A , Gary Dietachmayer https://orcid.org/0000-0001-8056-732X A , Joan Fernon A , Jim Fraser A , Wenming Lu A , Susan Rennie A , Peter Steinle https://orcid.org/0000-0002-0996-3386 A and Yi Xiao A
+ Author Affiliations
- Author Affiliations

A Australian Bureau of Meteorology, GPO Box 1289, Vic. 3001, Australia.

* Correspondence to: greg.roff@bom.gov.au

Journal of Southern Hemisphere Earth Systems Science 72(1) 1-18 https://doi.org/10.1071/ES21013
Submitted: 31 May 2021  Accepted: 8 December 2021  Published: 14 February 2022

© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of BoM. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

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 commissioning 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.

Keywords: ACCESS model, convection permitting model, Fractional Skill Score, high resolution NWP, verification metrics.