Second Response to Reviewer #2 of gmd-2018-156

This paper describes the splitting supercell idealized test case used in the 2016 Dynamical Core Model Intercomparison Project (DCMIP2016). These storms are useful testbeds for global atmospheric models because the horizontal scale of convective plumes is O(1km), emphasizing non-hydrostatic dynamics. The test case simulates a supercell on a reduced radius sphere with nominal resolutions ranging from 4km to 0.5km and is based on the work of Klemp et al. (2015). Models are initialized with an atmospheric environment conducive to supercell formation and forced with a small thermal perturbation. 5 A simplified Kessler microphysics scheme is coupled to the dynamical core to represent moist processes. Reference solutions for DCMIP2016 models are presented. Storm evolution is broadly similar between models, although differences in final solution exist. These differences are hypothesized to result from different numerical discretizations, physics-dynamics coupling, and numerical diffusion. Intramodel solutions generally converge as models approach 0.5km resolution, :::::::: although :::::::::: exploratory ::::::::: simulations :: at ::::::: 0.25km ::::: imply ::::: some ::::::::: dynamical :::: cores ::::::: require :::: more ::::::::: refinement :: to ::::: fully :::::::: converge. These results can be used as a 10

[1]  Hui Wan,et al.  Physics–Dynamics Coupling in Weather, Climate, and Earth System Models: Challenges and Recent Progress , 2016, Monthly Weather Review.

[2]  R. Heikes,et al.  DCMIP2016: A Review of Non-hydrostatic Dynamical Core Design and Intercomparison of Participating Models , 2017 .

[3]  Christian Kühnlein,et al.  A finite-volume module for cloud-resolving simulations of global atmospheric flows , 2017, J. Comput. Phys..

[4]  Craig S. Schwartz,et al.  Toward 1-km Ensemble Forecasts over Large Domains , 2017 .

[5]  F. Giraldo,et al.  The Impacts of Dry Dynamic Cores on Asymmetric Hurricane Intensification , 2016 .

[6]  F. Toepfer,et al.  Dynamical Core Evaluation Test Report for NOAA’s Next Generation Global Prediction System (NGGPS) , 2016 .

[7]  C. Jablonowski,et al.  A moist aquaplanet variant of the Held–Suarez test for atmospheric model dynamical cores , 2015 .

[8]  Sang Hun Park,et al.  Idealized global nonhydrostatic atmospheric test cases on a reduced‐radius sphere , 2015 .

[9]  C. Hannay,et al.  Impact of the dynamical core on the direct simulation of tropical cyclones in a high‐resolution global model , 2015 .

[10]  Charles A. Doswell,et al.  Tornadoes and Toraadic Storms: a Review of Conceptual Models , 2013 .

[11]  Ming Zhao,et al.  Some counterintuitive dependencies of tropical cyclone frequency on parameters in a GCM , 2012 .

[12]  Christiane Jablonowski,et al.  The pros and cons of diffusion, filters and fixers in Atmospheric General Circulation Models , 2011 .

[13]  Nils Wedi,et al.  A framework for testing global non‐hydrostatic models , 2009 .

[14]  W. Gallus,et al.  NOTES AND CORRESPONDENCE Comparison of Impacts of WRF Dynamic Core, Physics Package, and Initial Conditions on Warm Season Rainfall Forecasts , 2006 .

[15]  Christopher S. Bretherton,et al.  A new approach for 3D cloud‐resolving simulations of large‐scale atmospheric circulation , 2005 .

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

[17]  Nigel Wood,et al.  Analysis of the numerics of physics–dynamics coupling , 2002 .

[18]  Charles A. Doswell,et al.  The Tornado : its structure, dynamics, prediction, and hazards , 1993 .

[19]  Joseph B. Klemp,et al.  On the Rotation and Propagation of Simulated Supercell Thunderstorms , 1985 .

[20]  Joseph B. Klemp,et al.  The Dependence of Numerically Simulated Convective Storms on Vertical Wind Shear and Buoyancy , 1982 .

[21]  Joseph B. Klemp,et al.  The Influence of the Shear-Induced Pressure Gradient on Thunderstorm Motion , 1982 .

[22]  C. Doswell,et al.  Severe Thunderstorm Evolution and Mesocyclone Structure as Related to Tornadogenesis , 1979 .

[23]  J. Klemp,et al.  The Simulation of Three-Dimensional Convective Storm Dynamics , 1978 .

[24]  E. Kessler.  On the distribution and continuity of water substance in atmospheric circulations , 1969 .

[25]  K. Browning.  Airflow and Precipitation Trajectories Within Severe Local Storms Which Travel to the Right of the Winds , 1964 .