Assimilation of Doppler Radar Observations with a Regional 3DVAR System: Impact of Doppler Velocities on Forecasts of a Heavy Rainfall Case

Abstract In this paper, the impact of Doppler radar radial velocity on the prediction of a heavy rainfall event is examined. The three-dimensional variational data assimilation (3DVAR) system for use with the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) is further developed to enable the assimilation of radial velocity observations. Doppler velocities from the Korean Jindo radar are assimilated into MM5 using the 3DVAR system for a heavy rainfall case that occurred on 10 June 2002. The results show that the assimilation of Doppler velocities has a positive impact on the short-range prediction of heavy rainfall. The dynamic balance between atmospheric wind and thermodynamic fields, based on the Richardson equation, is introduced to the 3DVAR system. Vertical velocity (w) increments are included in the 3DVAR system to enable the assimilation of the vertical velocity component of the Doppler radial velocity observation. The forecast of the hydrometeor variables of cloud water (qc...

[1]  Heikki Järvinen,et al.  Doppler Radar Wind Data Assimilation with HIRLAM 3DVAR , 2004 .

[2]  Barry E. Schwartz,et al.  An Hourly Assimilation–Forecast Cycle: The RUC , 2004 .

[3]  Lewis F. Richardson,et al.  Weather Prediction by Numerical Process , 1922 .

[4]  Wei Huang,et al.  A Three-Dimensional Variational Data Assimilation System for MM5: Implementation and Initial Results , 2004 .

[5]  N. B. Ingleby,et al.  The Met. Office global three‐dimensional variational data assimilation scheme , 2000 .

[6]  Jorge Nocedal,et al.  On the limited memory BFGS method for large scale optimization , 1989, Math. Program..

[7]  Robert B. Wilhelmson,et al.  The Morphology of Several Tornadic Storms on 20 May 1977 , 1981 .

[8]  H. Pan,et al.  Nonlocal Boundary Layer Vertical Diffusion in a Medium-Range Forecast Model , 1996 .

[9]  Juanzhen Sun,et al.  Dynamical and Microphysical Retrieval from Doppler Radar Observations Using a Cloud Model and Its Adjoint. Part II: Retrieval Experiments of an Observed Florida Convective Storm , 1998 .

[10]  G. Foote,et al.  Determination of the Boundary Layer Airflow from a Single Doppler Radar , 1990 .

[11]  R. L. Vaughan,et al.  An Economical Procedure for Cartesian Interpolation and Display of Reflectivity Factor Data in Three-Dimensional Space , 1979 .

[12]  Yasushi Fujiyoshi,et al.  Determination of a Z-R Relationship for Snowfall Using a Radar and High Sensitivity Snow Gauges , 1990 .

[13]  Alan Shapiro,et al.  Retrieval of model initial fields from single-Doppler observations of a supercell thunderstorm , 2002 .

[14]  A. A. White,et al.  Large-Scale Atmosphere–Ocean Dynamics: A view of the equations of meteorological dynamics and various approximations , 2002 .

[15]  John Derber,et al.  The National Meteorological Center's spectral-statistical interpolation analysis system , 1992 .

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

[17]  Juanzhen Sun,et al.  Real-Time Low-Level Wind and Temperature Analysis Using Single WSR-88D Data , 2001 .

[18]  J. Derber,et al.  Variational Data Assimilation with an Adiabatic Version of the NMC Spectral Model , 1992 .

[19]  Alan Shapiro,et al.  Retrieval of Model Initial Fields from Single-Doppler Observations of a Supercell Thunderstorm. Part I: Single-Doppler Velocity Retrieval , 2002 .

[20]  R. Rasmussen,et al.  Explicit forecasting of supercooled liquid water in winter storms using the MM5 mesoscale model , 1998 .

[21]  David P. Jorgensen,et al.  A Z-R Relationship for Hurricanes , 1982 .

[22]  Yong-Run Guo,et al.  A Three-demiensional Variational (3DVAR) Data Assimilation System for Use With MM5 , 2003 .

[23]  Jidong Gao,et al.  A Variational Method for the Analysis of Three-Dimensional Wind Fields from Two Doppler Radars , 1999 .

[24]  P. Courtier,et al.  A strategy for operational implementation of 4D‐Var, using an incremental approach , 1994 .

[25]  Juanzhen Sun,et al.  Dynamical and Microphysical Retrieval from Doppler Radar Observations Using a Cloud Model and Its Adjoint. Part I: Model Development and Simulated Data Experiments. , 1997 .

[26]  Conrad L. Ziegler,et al.  Single- and Multiple-Doppler Radar Observations of Tornadic Storms , 1980 .