Orogenic Propagating Precipitation Systems over the United States in a Global Climate Model with Embedded Explicit Convection

Intheleeofmajormountainchainsworldwide,diurnalphysicsoforganizedpropagatingconvection project onto seasonal and climate time scales of the hydrologic cycle, but this phenomenon is not represented in conventional global climate models (GCMs). Analysis of an experimental version of the superparameterized (SP) Community Atmosphere Model (CAM) demonstrates that propagating orogenic nocturnal convection in the central U.S. warm season is, however, representable in GCMs that use the embedded explicit convection model approach [i.e., multiscale modeling frameworks (MMFs)]. SP-CAM admits propagating organized convective systems in the lee of the Rockies during synoptic conditions similar to those that generate mesoscale convective systems in nature. The simulated convective systems exhibit spatial scales, phase speeds, and propagation speeds comparable to radar observations, and the genesis mechanism in the model agrees qualitatively with established conceptual models. Convective heating and condensate structures are examined on both resolvedscales in SP-CAM, and coherently propagating cloud ‘‘metastructures’’ are shown to transcend individual cloud-resolving model arrays. In reconciling how this new mode of diurnal convective variabilityis admittedin SP-CAMdespite thesevereidealizations in the cloud-resolvingmodel configuration, an updated discussion is presented of what physics may transcend the re-engineered scale interface in MMFs. The authors suggest that the improved diurnal propagation physics in SP-CAM are mediated by large-scale first-baroclinic gravity wave interactions with a prognostic organization life cycle, emphasizing the physical importance of preserving ‘‘memory’’ at the inner resolved scale.

[1]  Mitchell W. Moncrieff,et al.  The Multiscale Organization of Moist Convection and the Intersection of Weather and Climate , 2013 .

[2]  Richard Neale,et al.  Parameterizing Convective Organization to Escape the Entrainment Dilemma , 2011 .

[3]  Ronald B. Smith,et al.  The Detection and Significance of Diurnal Pressure and Potential Vorticity Anomalies East of the Rockies , 2010 .

[4]  R. Marchand,et al.  An analysis of cloud cover in multiscale modeling framework global climate model simulations using 4 and 1 km horizontal grids , 2010 .

[5]  Roger A. Pielke,et al.  Ten‐year climatology of summertime diurnal rainfall rate over the conterminous U.S. , 2010 .

[6]  Christopher A. Davis,et al.  Environmental Controls on the Simulated Diurnal Cycle of Warm-Season Precipitation in the Continental United States , 2010 .

[7]  David A. Randall,et al.  An ocean‐atmosphere climate simulation with an embedded cloud resolving model , 2010 .

[8]  Wei-Kuo Tao,et al.  Multiscale cloud system modeling , 2009 .

[9]  David A. Randall,et al.  Structure of the Madden-Julian Oscillation in the Superparameterized CAM , 2009 .

[10]  R. Marchand,et al.  A comparison of simulated cloud radar output from the multiscale modeling framework global climate model with CloudSat cloud radar observations , 2009 .

[11]  Richard C. J. Somerville,et al.  Assessing the Diurnal Cycle of Precipitation in a Multi‐Scale Climate Model , 2009 .

[12]  M. Pritchard,et al.  Empirical orthogonal function analysis of the diurnal cycle of precipitation in a multi‐scale climate model , 2009 .

[13]  S. Klein,et al.  On the diurnal cycle of deep convection, high-level cloud, and upper troposphere water vapor in the Multiscale Modeling Framework , 2008 .

[14]  Richard E. Carbone,et al.  Rainfall Occurrence in the U.S. Warm Season: The Diurnal Cycle* , 2008 .

[15]  R. Arritt,et al.  Idealized Mesoscale Convective System Structure and Propagation Using Convective Parameterization , 2008 .

[16]  David A. Randall,et al.  Evaluation of the Simulated Interannual and Subseasonal Variability in an AMIP-Style Simulation Using the CSU Multiscale Modeling Framework , 2008 .

[17]  S. Schubert,et al.  Role of convection triggers in the simulation of the diurnal cycle of precipitation over the United States Great Plains in a general circulation model , 2008 .

[18]  I. Jirak,et al.  Observational Analysis of the Predictability of Mesoscale Convective Systems , 2007 .

[19]  M. Moncrieff.  A theory of organized steady convection and its transport properties , 2007 .

[20]  Mitchell W. Moncrieff,et al.  Representing convective organization in prediction models by a hybrid strategy , 2006 .

[21]  S. Klein,et al.  Role of eastward propagating convection systems in the diurnal cycle and seasonal mean of summertime rainfall over the U.S. Great Plains , 2006 .

[22]  G. Bryan,et al.  Mechanisms supporting long-lived episodes of propagating nocturnal convection within a 7-day WRF model simulation , 2006 .

[23]  Christopher A. Davis,et al.  Corridors of Warm Season Precipitation in the Central United States , 2006 .

[24]  D. Randall,et al.  Simulations of the Atmospheric General Circulation Using a Cloud-Resolving Model as a Superparameterization of Physical Processes , 2005 .

[25]  R. Houze.  Mesoscale convective systems , 2004 .

[26]  D. Randall,et al.  Cloud resolving modeling of the ARM summer 1997 IOP: Model formulation, results, uncertainties, and sensitivities , 2003 .

[27]  D. Randall,et al.  A cloud resolving model as a cloud parameterization in the NCAR Community Climate System Model: Preliminary results , 2001 .

[28]  John D. Tuttle,et al.  Inferences of Predictability Associated with Warm Season Precipitation Episodes , 2001 .

[29]  J. Michael Fritsch,et al.  The Large-Scale Environments of the Global Populations of Mesoscale Convective Complexes , 2000 .

[30]  Piotr K. Smolarkiewicz,et al.  CRCP: a cloud resolving convection parameterization for modeling the tropical convecting atmosphere , 1999 .

[31]  R. Houze,et al.  Kinematic characteristics of air flowing into and out of precipitating convection over the west Pacific warm pool: An airborne Doppler radar survey , 1999 .

[32]  D. Durran,et al.  The Influence of Convectively Generated Thermal Forcing on the Mesoscale Circulation around Squall Lines , 1996 .

[33]  S. Ghan,et al.  Simulation of the Great Plains Low-Level Jet and Associated Clouds by General Circulation Models , 1996 .

[34]  Mitchell W. Moncrieff,et al.  Organized convective systems : archetypal dynamical models, mass and momentum flux theory, and parametrization , 1992 .

[35]  D. Raymond,et al.  A Theory for Long-Lived Mesoscale Convective Systems , 1990 .

[36]  W. Cotton,et al.  Numerical Study of an Observed Orogenic Mesoscale Convective System. Part 1: Simulated Genesis and Comparison with Observations , 1989 .

[37]  Mitchell W. Moncrieff,et al.  A Numerical Investigation of the Organization and Interaction of the Convective and Stratiform Regions of Tropical Squall Lines , 1988 .

[38]  R. Rotunno,et al.  A Theory for Strong, Long-Lived Squall Lines , 1988 .

[39]  R. Maddox.  Large-Scale Meteorological Conditions Associated with Midlatitude, Mesoscale Convective Complexes , 1983 .

[40]  M. Moncrieff,et al.  Dynamical models of two‐dimensional downdraughts , 1980 .

[41]  D. Randall,et al.  Convective Precipitation Variability as a Tool for General Circulation Model Analysis , 2007 .

[42]  W. Collins,et al.  Description of the NCAR Community Atmosphere Model (CAM 3.0) , 2004 .

[43]  W. Grabowski,et al.  Large‐scale organization of tropical convection in two‐dimensional explicit numerical simulations , 2001 .

[44]  J. Michael Fritsch,et al.  The global population of mesoscale convective complexes , 1997 .