Vertical Velocity in the Gray Zone

We describe how convective vertical velocities wc vary in the “gray zone” of horizontal resolution, using both hydrostatic and nonhydrostatic versions of GFDL's FV3 dynamical core, as well as analytical solutions to the equations of motion. We derive a simple criterion (based on parcel geometries) for a model to resolve convection, and find that O(100 m) resolution can be required for convergence of wc . We also find, both numerically and analytically, that hydrostatic systems overestimate wc , by a factor of 2–3 in the convection‐resolving regime. This overestimation is simply understood in terms of the “effective buoyancy pressure” of Jeevanjee and Romps (2015, 2016).

[1]  Adcroft Alistair,et al.  MITgcm User Manual , 2018 .

[2]  P. Hassanzadeh,et al.  A perspective on climate model hierarchies , 2017 .

[3]  B. Vogel,et al.  Are atmospheric updrafts a key to unlocking climate forcing and sensitivity , 2016 .

[4]  Steven C. Sherwood,et al.  A Numerical Investigation of Cumulus Thermals , 2016 .

[5]  H. Morrison.  Impacts of Updraft Size and Dimensionality on the Perturbation Pressure and Vertical Velocity in Cumulus Convection. Part I: Simple, Generalized Analytic Solutions , 2016 .

[6]  H. Morrison.  Impacts of Updraft Size and Dimensionality on the Perturbation Pressure and Vertical Velocity in Cumulus Convection. Part II: Comparison of Theoretical and Numerical Solutions and Fully Dynamical Simulations , 2016 .

[7]  D. Romps,et al.  Effective buoyancy at the surface and aloft , 2016 .

[8]  H. Morrison,et al.  Effects of Horizontal and Vertical Grid Spacing on Mixing in Simulated Squall Lines and Implications for Convective Strength and Structure , 2015 .

[9]  D. Romps,et al.  Sticky Thermals: Evidence for a Dominant Balance between Buoyancy and Drag in Cloud Updrafts , 2015 .

[10]  D. Romps,et al.  Effective Buoyancy, Inertial Pressure, and the Mechanical Generation of Boundary Layer Mass Flux by Cold Pools , 2015 .

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

[12]  Prabhat,et al.  The effect of horizontal resolution on simulation quality in the Community Atmospheric Model, CAM5.1 , 2014 .

[13]  Masaki Satoh,et al.  Responses of Tropical and Subtropical High-Cloud Statistics to Global Warming , 2014 .

[14]  A. Clark,et al.  Comparison of Next-Day Convection-Allowing Forecasts of Storm motion on 1- and 4-km Grids , 2014 .

[15]  Steven C. Sherwood,et al.  Slippery Thermals and the Cumulus Entrainment Paradox , 2013 .

[16]  Shian-Jiann Lin,et al.  Seasonal Predictions of Tropical Cyclones Using a 25-km-Resolution General Circulation Model , 2013 .

[17]  Shian-Jiann Lin,et al.  A Two-Way Nested Global-Regional Dynamical Core on the Cubed-Sphere Grid , 2013 .

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

[19]  G. Bryan,et al.  Sensitivity of a Simulated Squall Line to Horizontal Resolution and Parameterization of Microphysics , 2012 .

[20]  William M. Putman,et al.  Cloud‐system resolving simulations with the NASA Goddard Earth Observing System global atmospheric model (GEOS‐5) , 2011 .

[21]  P. Markowski,et al.  Mesoscale Meteorology in Midlatitudes , 2010 .

[22]  David M. Romps,et al.  The Dry-Entropy Budget of a Moist Atmosphere , 2008 .

[23]  S. J. Weiss,et al.  Some Practical Considerations Regarding Horizontal Resolution in the First Generation of Operational Convection-Allowing NWP , 2008 .

[24]  Nigel Roberts,et al.  Characteristics of high-resolution versions of the Met Office unified model for forecasting convection over the United Kingdom , 2008 .

[25]  S. Garner,et al.  Sensitivity of Radiative–Convective Equilibrium Simulations to Horizontal Resolution , 2006 .

[26]  Shian‐Jiann Lin.  A “Vertically Lagrangian” Finite-Volume Dynamical Core for Global Models , 2004 .

[27]  J. Wyngaard.  Toward Numerical Modeling in the “Terra Incognita” , 2004 .

[28]  R. Davies-Jones.  An Expression for Effective Buoyancy in Surroundings with Horizontal Density Gradients , 2003 .

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

[30]  W. Skamarock,et al.  The resolution dependence of explicitly modeled convective systems , 1997 .

[31]  Kazuo Saito,et al.  Hydrostatic and Non-Hydrostatic Simulations of Moist Convection: Applicability of the Hydrostatic Ap , 1995 .

[32]  I. Orlanski.  The Quasi-Hydrostatic Approximation , 1981 .

[33]  P. Das.  A Non-Archimedean Approach to the Equations of Convection Dynamics , 1979 .

[34]  A. Arakawa,et al.  Interaction of a Cumulus Cloud Ensemble with the Large-Scale Environment, Part I , 1974 .

[35]  Betsy Woodward,et al.  The motion in and around isolated thermals , 1959 .

[36]  R. S. Scorer,et al.  Experiments on convection of isolated masses of buoyant fluid , 1957, Journal of Fluid Mechanics.