On the Definition of Precipitation Efficiency

A modified definition of precipitation efficiency (PE) is proposed based on either cloud microphysics precipitation efficiency (CMPE) or water cycling processes including water vapor and hydrometeor species [large-scale precipitation efficiency (LSPE)]. These PEs are examined based on a two-dimensional cloudresolving simulation. The model is integrated for 21 days with the imposed large-scale vertical velocity, zonal wind, and horizontal advections obtained from the Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE). It is found that the properly defined PEs include all moisture and hydrometeor sources associated with surface rainfall processes so that they range from 0% to 100%. Furthermore, the modified LSPE and CMPE are highly correlated. Their linear correlation coefficient and root-mean-squared difference are insensitive to the spatial scales of averaged data and are moderately sensitive to the time period of averaged data.

[1]  Wojciech W. Grabowski,et al.  Cloud-Resolving Modeling of Tropical Cloud Systems during Phase III of GATE. Part I: Two-Dimensional Experiments. , 1996 .

[2]  C. Doswell,et al.  Flash Flood Forecasting: An Ingredients-Based Methodology , 1996 .

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

[4]  Xiaoqing Wu,et al.  Long-Term Behavior of Cloud Systems in TOGA COARE and Their Interactions with Radiative and Surface Processes. Part I: Two-Dimensional Modeling Study , 1998 .

[5]  J. Fritsch,et al.  Numerical Prediction of Convectively Driven Mesoscale Pressure Systems. Part I: Convective Parameterization , 1980 .

[6]  Ka-Ming Lau,et al.  Dominant Cloud Microphysical Processes in a Tropical Oceanic Convective System: A 2D Cloud Resolving Modeling Study , 2002 .

[7]  Ming-Jen Yang,et al.  Estimation of Oceanic Precipitation Efficiency in Cloud Models , 2005 .

[8]  M. Chong,et al.  A Tropical Squall Line Observed during the COPT 81 Experiment in West Africa. Part II: Water Budget , 1989 .

[9]  K. Lau,et al.  Large-Scale Forcing and Cloud–Radiation Interaction in the Tropical Deep Convective Regime , 1999 .

[10]  K. Lau,et al.  Precipitation Efficiency in the Tropical Deep Convective Regime : A 2-D Cloud Resolving Modeling Study , 2001 .

[11]  S. P. Anderson,et al.  Surface meteorology and air-sea fluxes in the western equatorial Pacific warm pool during the TOGA c , 1996 .

[12]  W. Tao,et al.  Response of Deep Tropical Cumulus Clouds to Mesoscale Processes , 1980 .

[13]  K. Lau,et al.  Radiative–Convective Processes in Simulated Diurnal Variations ofTropical Oceanic Convection , 1998 .

[14]  Robert F. Adler,et al.  A Proposed Tropical Rainfall Measuring Mission (TRMM) Satellite , 1988 .

[15]  Roscoe R. Braham,et al.  THE WATER AND ENERGY BUDGETS OF THE THUNDERSTORM AND THEIR RELATION TO THUNDERSTORM DEVELOPMENT , 1952 .

[16]  John S. Kain,et al.  Convective parameterization for mesoscale models : The Kain-Fritsch Scheme , 1993 .

[17]  Ka-Ming Lau,et al.  The Tropical Water and Energy Cycles in a Cumulus Ensemble Model. Part I: Equilibrium Climate , 1994 .

[18]  Minghua Zhang,et al.  Constrained Variational Analysis of Sounding Data Based on Column-Integrated Budgets of Mass, Heat, Moisture, and Momentum: Approach and Application to ARM Measurements. , 1997 .

[19]  Joanne Simpson,et al.  Goddard Cumulus Ensemble Model. Part I: Model Description , 1993 .

[20]  J. Simpson,et al.  The Atmospheric Energy Budget and Large-Scale Precipitation Efficiency of Convective Systems during TOGA COARE, GATE, SCSMEX, and ARM: Cloud-Resolving Model Simulations , 2004 .

[21]  Y. Ogura,et al.  Response of Tradewind Cumuli to Large-Scale Processes , 1980 .

[22]  G. Scialom,et al.  A Tropical Squall Line Observed during the COPT 81 Experiment in West Africa. Part 1: Kinematic Structure Inferred from Dual-Doppler Radar Data , 1987 .

[23]  R. Hemler,et al.  Numerical simulation of deep tropical convection associated with large-scale convergence , 1986 .

[24]  Ka-Ming Lau,et al.  Warm rain processes over tropical oceans and climate implications , 2003 .

[25]  A. H. Auer,et al.  Estimates of Air and Moisture Flux into Hailstorms on the High Plains , 1968 .

[26]  H. Kuo.  On Formation and Intensification of Tropical Cyclones Through Latent Heat Release by Cumulus Convection , 1965 .

[27]  H. Kuo.  Further Studies of the Parameterization of the Influence of Cumulus Convection on Large-Scale Flow , 1974 .

[28]  W. Tao,et al.  Factors Responsible for Precipitation Efficiencies in Midlatitude and Tropical Squall Simulations , 1996 .

[29]  G. Heymsfield,et al.  Structure and evolution of a severe squall line over Oklahoma , 1985 .

[30]  G. Grell.  Prognostic evaluation of assumptions used by cumulus parameterizations , 1993 .

[31]  David A. Randall,et al.  Explicit Simulation of Cumulus Ensembles with the GATE Phase III Data: Comparison with Observations , 1996 .

[32]  Xiaofan Li,et al.  Surface rainfall processes as simulated in a cloud-resolving model , 2005 .