Research Article The Sensitivity of Heavy Precipitation to Horizontal Resolution, Domain Size, and Rain Rate Assimilation: Case Studies with a Convection-Permitting Model Xingbao Wang, Peter Steinle, Alan Seed, and Yi Xiao Research and Development Branch, Bureau of Meteorology, Melbourne, VIC 3008, Australia Correspondence should be addressed to Xingbao Wang; xingbao.wang@bom.gov.au Received 5 October 2015; Revised 16 November 2015; Accepted 17 November 2015 Academic Editor: Hann-Ming H. Juang Copyright © 2016 Xingbao Wang et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Te Australian Community Climate and Earth-System Simulator (ACCESS) is used to test the sensitivity of heavy precipitation to various model confgurations: horizontal resolution, domain size, rain rate assimilation, perturbed physics, and initial condition uncertainties, through a series of convection-permitting simulations of three heavy precipitation (greater than 200 mm day −1 ) cases in diferent synoptic backgrounds. Te larger disparity of intensity histograms and rainfall fuctuation caused by diferent model confgurations from their mean and/or control run indicates that heavier precipitation forecasts have larger uncertainty. A cross- verifcation exercise is used to quantify the impacts of diferent model parameters on heavy precipitation. Te dispersion of skill scores with control run used as “truth” shows that the impacts of the model resolution and domain size on the quantitative precipitation forecast are not less than those of perturbed physics and initial feld uncertainties in these not intentionally selected heavy precipitation cases. Te result indicates that model resolution and domain size should be considered as part of probabilistic precipitation forecasts and ensemble prediction system design besides the model initial feld uncertainty. 1. Introduction Many studies show the importance of higher resolution in improving the forecast skill. Te increased resolution has the beneft of reducing numerical truncation, of explicitly resolving dynamical interactions for wider range of spatial scales, and permits the simulation of fne-scale details and hence of relying less strongly on parameterization of sub- grid scale processes. Weisman et al. [1], Done et al. [2], Lean et al. [3], Schwartz et al. [4], and many others have shown that convection-permitting models yield qualitatively more realistic precipitation felds and are quantitatively more skillful than lower-resolution simulations with parameterized convection. Te results from short-range weather forecasting [5–7] also indicate that such convection-permitting models outperform those coarser resolution models that require a convective parameterization. However, due to the high computational cost of integration of high resolution model, a necessary price for higher resolution is using limited horizon- tal domain. Te limited domains models need artifcial lateral boundaries, which introduce additional uncertainties and errors into the weather forecast. Te emphasis on horizontal resolution in most mesoscale simulation is based on the implicit assumption that errors from artifcial lateral bound- aries and the efects of limited domain size may not play a signifcant role in the dynamics of the mesoscale system. Teoretically, one would like to suppose that grid spacing is fne enough to resolve the phenomena of interest and domain size is large enough that the placement of the boundaries would not unduly contaminate the solution, at least for the time scales of interest. However, studies have shown that both of the domain size and horizontal resolution of limited area model infuence the spectrum of resolved scale and the nature of scale interaction in the model dynamics [8, 9]. Stevens et al. [10] used a cloud model studying the sensitivity of shallow cumulus convection to model domain and resolution and found that domain size and resolution have big impacts on the cloud structure and their statistical characteristics. Laprise et al. [11] discussed many limitations and sources of error associated with limited area models, such as the resolution Hindawi Publishing Corporation Advances in Meteorology Volume 2016, Article ID 7943845, 20 pages http://dx.doi.org/10.1155/2016/7943845