Advancd Regional Prediction Advancd Regional Prediction System (ARPS)System (ARPS)

Ming Xue Ming Xue mxue@ou.edumxue@ou.edu

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

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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

Formulation (Continued …)Formulation (Continued …)

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)

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Incremental Analysis Update CyclesIncremental Analysis Update Cycles

(from Brewster 2003)

ADAS analysis – ADAS analysis – Total uTotal u

ADASBackground

73x73x43 grid, dx=12km

ADAS AnalysisADAS Analysis– Total – Total

Background ADAS

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.

Vertical Boundary ConditionVertical Boundary Condition

• 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

turbulence)turbulence)

See PDF fileSee PDF file

RadiationRadiation

Radiation ParameterizationRadiation Parameterization

• 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)

Radiation Fluxes VerificationRadiation Fluxes Verification

Microphysics SchemesMicrophysics Schemes

• 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

microphysicsmicrophysics

Convective ParameterizationConvective Parameterization

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