Advancd Regional Prediction Advancd Regional Prediction System (ARPS) System (ARPS) Ming Xue Ming Xue [email protected][email protected]School of Meteorology School of Meteorology and and Center for Analysis and Prediction of Storms Center for Analysis and Prediction of Storms University of Oklahoma University of Oklahoma sf n
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Advancd Regional Prediction System (ARPS) Ming Xue [email protected] School of Meteorology and Center for Analysis and Prediction of Storms University of Oklahoma.
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Advancd Regional Prediction Advancd Regional Prediction System (ARPS)System (ARPS)
School of Meteorology School of Meteorology and and
Center for Analysis and Prediction of StormsCenter for Analysis and Prediction of StormsUniversity of OklahomaUniversity of Oklahoma
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Model Dynamics, Equations and Model Dynamics, Equations and Numerical FormualtionsNumerical Formualtions
See PDF fileSee PDF file
Initial ConditionInitial Condition
ARPS ComponentsARPS Components
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ARPS Data Analysis System (ADAS)
ARPS Numerical Model– Multi-scale non-hydrostatic prediction model with comprehensive physics
– Plots and images – Animations – Diagnostics and statistics – Forecast evaluation
– Ingest – Quality control – Objective analysis – Archival
Single-Doppler Velocity Retrieval (SDVR)
4-D Variational
Data Assimilation
Variational Vel -ocity Adjustment
& Thermo-dynamic Retrieval
ARPS Data Assimilation System (ARPSDAS)
ARPSPLT and ARPSVIEW
Inc
om
ing
d
ata
Oklahoma MesonetWSR-88D Wideband
ASOS/AWOS
SAO
ACARS
CLASS
Mobile Mesonet
Profilers
Rawinsondes
Satellite
Lateral boundary conditions from large-scale models
Gridded first guessData Acquisition
& AnalysisData Acquisition
& Analysis
Forecast GenerationForecast Generation
Parameter Retrieval and 4DDAParameter Retrieval and 4DDA
Product Generation and Data Support System
Product Generation and Data Support System
Ways to Initialize ARPSWays to Initialize ARPS
• Idealized, single soundingIdealized, single sounding
• Interpolation from GFS, Eta, RUC, etcInterpolation from GFS, Eta, RUC, etc
• ADASADAS
ARPS Data Analysis System (ADAS)ARPS Data Analysis System (ADAS)
• Manages the real time ingest, QC, objective analysis of observationsManages the real time ingest, QC, objective analysis of observations
Doppler radar data (NIDS, base Level II from n systems, VAD)Doppler radar data (NIDS, base Level II from n systems, VAD) MDCRS commercial aircraft wind and temperature reportsMDCRS commercial aircraft wind and temperature reports Wind profilersWind profilers RAOBS (conventional, CLASS, dropsondes)RAOBS (conventional, CLASS, dropsondes) Mobile and fixed mesonetsMobile and fixed mesonets SAO and METAR observationsSAO and METAR observations GOES satellite visible and IR data for cloud analysisGOES satellite visible and IR data for cloud analysis NCEP gridded model outputNCEP gridded model output
• Based on Bratseth successive correction methodBased on Bratseth successive correction method
• Handles retrieved radar data (from SDVR et al)Handles retrieved radar data (from SDVR et al)
• Had its root in FSL LAPS. Data format is about the only one left though.Had its root in FSL LAPS. Data format is about the only one left though.
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Braseth Analysis SchemeBraseth Analysis Scheme
• ADAS use the Bratseth analysis scheme which is a ADAS use the Bratseth analysis scheme which is a successive correction schemesuccessive correction scheme
• The scheme theoretically converges to optimal interpolation The scheme theoretically converges to optimal interpolation (O/I), but without explicit inversion of large matrices(O/I), but without explicit inversion of large matrices
• Multi-pass strategy used where more detailed data can be Multi-pass strategy used where more detailed data can be introduced after a few iterations using broad-scale data. introduced after a few iterations using broad-scale data.
• Like OI, the Bratseth method accounts for the relative error Like OI, the Bratseth method accounts for the relative error
between the background and each observation source, and is between the background and each observation source, and is relatively insensitive to large variations in data density. relatively insensitive to large variations in data density.
• Vertical correction in terms of z or Vertical correction in terms of z or
Formulation of Bratseth SchemeFormulation of Bratseth Scheme
ARPS Data Analysis System (ADAS)ARPS Data Analysis System (ADAS)
• User specifies background error covariances and structure functions. User specifies background error covariances and structure functions. Codes to calculate background error statistics being developed.Codes to calculate background error statistics being developed.
• Performed on ARPS native (terrain-following) gridPerformed on ARPS native (terrain-following) grid
• 3-D cloud analysis and diabatic initialization package using GOES, 3-D cloud analysis and diabatic initialization package using GOES, Doppler radar and surface data. Doppler radar and surface data.
• Water vapor, cloud, rain, ice and temperature fields are affected by the Water vapor, cloud, rain, ice and temperature fields are affected by the cloud analysiscloud analysis
• Used to initialize realtime high-res (~kms) forecasts at CAPS since Used to initialize realtime high-res (~kms) forecasts at CAPS since 19961996
• Linked closely with ARPS data assimilation system (via, e.g., Linked closely with ARPS data assimilation system (via, e.g., intermittent assimilation, incremental analysis update method)intermittent assimilation, incremental analysis update method)
Example of Initial Condition with cloud Example of Initial Condition with cloud analysis on a 3km Gridanalysis on a 3km Grid
Application to fine-scale analysis at Application to fine-scale analysis at Kennedy Space Center (Case et al 2002 Kennedy Space Center (Case et al 2002
Wea. Forecasting)Wea. Forecasting)
Boundary ConditionsBoundary Conditions
• Lateral Boundary ConditionsLateral Boundary Conditions Rigid, zero-gradient, periodic Rigid, zero-gradient, periodic Open/radiative LBC (only applied to normal velocity)Open/radiative LBC (only applied to normal velocity) Externally (can be from the same model) forcedExternally (can be from the same model) forced
o Davies-type relaxation zone, arbitrary widthDavies-type relaxation zone, arbitrary widtho w not forcedw not forcedo variables (e.g., water) not found in exbc are variables (e.g., water) not found in exbc are
excluded from relaxation – zero gradient is excluded from relaxation – zero gradient is usually appliedusually applied
o Ensure same terrain at nesting boundariesEnsure same terrain at nesting boundaries Carpenter (1982) – radiation BC with external
forcing(?)o Carpenter, K. M., 1982: Note on radiation conditions for the
lateral boundaries of limited-area numerical models. Quart. J. Roy. Meteor. Soc., 108, 717-719.
• Radiation top BC based on cosine Fourier Radiation top BC based on cosine Fourier transform (Klemp and Durran 1983) transform (Klemp and Durran 1983) periodicity requirement at the top relaxedperiodicity requirement at the top relaxed Still based on linearized equations – difficult to apply Still based on linearized equations – difficult to apply
to large domainto large domain
• Upper boundary sponge/absorbing layerUpper boundary sponge/absorbing layer relaxation to coarse grid/external model solution in the relaxation to coarse grid/external model solution in the
layerlayer or relaxation to the mean stateor relaxation to the mean state
• Rigid, zero-gradient and periodic top-bottom BCRigid, zero-gradient and periodic top-bottom BC• Semi-slip lower BCSemi-slip lower BC
Stratiform Clouds and PrecipitationStratiform Clouds and Precipitation
• Microphysics parameterization for grid-scale Microphysics parameterization for grid-scale precipitationprecipitation
• Can be used together with cumulus Can be used together with cumulus parameterization schemesparameterization schemes
• Option to allow condensation at subsatuation Option to allow condensation at subsatuation (<100% RH)(<100% RH) helps retaining clouds in IC for large grid spacinghelps retaining clouds in IC for large grid spacing improves surface temperature forecast at low-resolution improves surface temperature forecast at low-resolution
by introducing clouds earlierby introducing clouds earlier
• Sedimentation term treated implicitly or using Sedimentation term treated implicitly or using time splittingtime splitting
• SGS TurbulenceSGS Turbulence
Smagorinsky-Lilly, 1.5-order TKE, Germano dynamic closureSmagorinsky-Lilly, 1.5-order TKE, Germano dynamic closure Fully three dimensional formulation, including map factorFully three dimensional formulation, including map factor Simplified 1-D option available for efficiency purposeSimplified 1-D option available for efficiency purpose
• Cumulus ParameterizationCumulus Parameterization Kuo schemeKuo scheme Old and New versions of Kain-Fritsch cumulus parameterizationsOld and New versions of Kain-Fritsch cumulus parameterizations Eta Betts-Miller-Jancic schemeEta Betts-Miller-Jancic scheme
• MicrophysicsMicrophysics Kessler warm rainKessler warm rain Lin-Tao ice microphysicsLin-Tao ice microphysics Schultz NEM grid-scale microphysicsSchultz NEM grid-scale microphysics
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Model Physics Model Physics
• PBL scheme PBL scheme Convective PBL mixing parameterization based on 1.5-order TKE formulation (Xue et Convective PBL mixing parameterization based on 1.5-order TKE formulation (Xue et
al 1996)al 1996)
• Surface Physics (fluxes)Surface Physics (fluxes) Stability-dependent bulk aerodynamic drag for surface heat, momentum, and moisture Stability-dependent bulk aerodynamic drag for surface heat, momentum, and moisture
fluxesfluxes
• Soil ModelSoil Model 2-layer soil model (multiple soil types in 1 grid cell; API initialization)2-layer soil model (multiple soil types in 1 grid cell; API initialization) A new multi-layer soil modelA new multi-layer soil model High-resolution surface characteristics data base (consistency among surface fields High-resolution surface characteristics data base (consistency among surface fields
important)important)
• RadiationRadiation Full long- and short-wave radiation (NASA code) including cloud interactions, cloud Full long- and short-wave radiation (NASA code) including cloud interactions, cloud
shadowing, and terrain gradient effectsshadowing, and terrain gradient effects
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Model Physics (continued)Model Physics (continued)
ARPS Physical Processes
Subgrid Scale FluxesSubgrid Scale Fluxes(Land surface, surface layer, PBL and SGS (Land surface, surface layer, PBL and SGS
• ARPS radiation package came from NASA GSFC. ARPS radiation package came from NASA GSFC. Shortwave is based on Chou (1990; 1992)Shortwave is based on Chou (1990; 1992) Longwave based on Chou and Suarez (1994)Longwave based on Chou and Suarez (1994) Cloud-radiation interaction described in Tao et al (1996)Cloud-radiation interaction described in Tao et al (1996)
• Allows checkboard-type staggered calculations to save Allows checkboard-type staggered calculations to save computationcomputation
• Recently implemented terrain shading effectRecently implemented terrain shading effect• Terrain slope accounted forTerrain slope accounted for• Cloud fraction diagnosed from RH and q’sCloud fraction diagnosed from RH and q’s• Verifications against OK Mesonet radiation measurements Verifications against OK Mesonet radiation measurements
show good agreement, in clear sky conditions at leastshow good agreement, in clear sky conditions at least
Shortwave RadiationShortwave Radiation
• Solar spectrum is divided into the ultraviolet and visible Solar spectrum is divided into the ultraviolet and visible region (<0.69region (<0.69mm, and the near-infrared (IR) region , and the near-infrared (IR) region (>0.69(>0.69mm, ,
• UV and visible region includes ozone absorption, Rayleigh UV and visible region includes ozone absorption, Rayleigh and cloud scattering. It is further divided into 4 bands, with and cloud scattering. It is further divided into 4 bands, with effective ozone absorption and scattering coefficients effective ozone absorption and scattering coefficients given to each bandgiven to each band
• The IR region includes absorption due to water vapor, The IR region includes absorption due to water vapor, cloud, COcloud, CO22, O, O33 and scattering due to clouds. and scattering due to clouds. Further division into 7 water vapor absorption bands, with k-Further division into 7 water vapor absorption bands, with k-
distribution method used to calculate the absorption. distribution method used to calculate the absorption. Liou et al (1988) 4-stream discrete ordinate scattering algorithm Liou et al (1988) 4-stream discrete ordinate scattering algorithm
used for multiscattering in cloud layerused for multiscattering in cloud layer Single scattering albedo from King et al (1990)Single scattering albedo from King et al (1990)
Longwave RadiationLongwave Radiation
• IR spectrum divided into 8 bandsIR spectrum divided into 8 bands• Water vapor transmission function computed used k-Water vapor transmission function computed used k-
distribution methoddistribution method• COCO22 and O and O33 transmission functions computed using lookup transmission functions computed using lookup
tablestables• Includes aerosol effectsIncludes aerosol effects• Absorption due to cloud hydrometeors also included. Absorption due to cloud hydrometeors also included.
Clouds assumed to be gray and nonscatteringClouds assumed to be gray and nonscattering• Cloud optical propertiesCloud optical properties
Scheme 1: Broadband emissivity method of Stevens (1978, 1984)Scheme 1: Broadband emissivity method of Stevens (1978, 1984) Scheme 2 follows Fu and Liou (1993), Sui et al (1996)Scheme 2 follows Fu and Liou (1993), Sui et al (1996)
• Kessler warm rain microphysics (qc and qr)Kessler warm rain microphysics (qc and qr)• Lin et al (1983) ice microphysics Lin et al (1983) ice microphysics
includes rain, cloud water, cloud ice, snow, includes rain, cloud water, cloud ice, snow, graupel/hail,graupel/hail,
lookup tables for power and exponential functionslookup tables for power and exponential functions ice-water saturation adjustment procedure of Tao et al ice-water saturation adjustment procedure of Tao et al
(1989)(1989) modifications to hydrometeo fall speeds (Ferrier 1994 modifications to hydrometeo fall speeds (Ferrier 1994
and updated coefficients)and updated coefficients)
• Shultz (1995) simplified ice scheme (also include Shultz (1995) simplified ice scheme (also include 3 ice categories)3 ice categories)
ARPS Ice Microphysics Processes
~ 30 processes
Accumulated Accumulated Precipitation from Precipitation from
1977 Del City 1977 Del City Supercell Storms Supercell Storms
with warmrain and with warmrain and ice microphysicsice microphysics
Simulation of 1977 Del City Supercell Simulation of 1977 Del City Supercell Storms with warmrain and ice Storms with warmrain and ice
Convective Clouds and PrecipitationConvective Clouds and Precipitation
• At high resolutions (=< 3km), use ‘explicit’ At high resolutions (=< 3km), use ‘explicit’ microphysics, hopefully the model can microphysics, hopefully the model can resolve the convection wellresolve the convection well
• Cumulus parameterization schemesCumulus parameterization schemes Kuo schemeKuo scheme Old and new Kain-Fritch schemesOld and new Kain-Fritch schemes Betts-Miller-Janjic schemeBetts-Miller-Janjic scheme New K-F scheme used mostNew K-F scheme used most
Use of Cumulus SchemeUse of Cumulus Scheme
• K-F scheme used mostK-F scheme used most• New K-F scheme using at 27 and 9km New K-F scheme using at 27 and 9km
during IHOP realtime forecastduring IHOP realtime forecast• BMJ scheme tends to produce much BMJ scheme tends to produce much
smoother precipitation fieldsmoother precipitation field• Cold pool important for propagation of Cold pool important for propagation of
convective systems over the plainsconvective systems over the plains• Triggering of spurious propagating Triggering of spurious propagating
precipitation pattern observed during IHOPprecipitation pattern observed during IHOP
CAPS Real Time Forecast CAPS Real Time Forecast Domain during IHOP_2002Domain during IHOP_2002
273×195
183×163
213×131
June 15, 2002, 9km GridJune 15, 2002, 9km Grid
NCEP Hourly Precip 9 km Forecast Precip Hourly Rate.
24 hour forecast
June 15, 2002 – 3km gridJune 15, 2002 – 3km grid
NCEP Hourly Precip Analysis 3 km Forecast Hourly Precip Rate
11 hour forecast
00-12UTC, June 13, 2002, Hourly Precip00-12UTC, June 13, 2002, Hourly Precip