Operational Use of the Rapid Update Cycle

COMAP Symposium 99-1

20 May 1999

Stan Benjamin - NOAA/FSLbenjamin@fsl.noaa.govhttp://maps.fsl.noaa.gov - RUC web page

What Runs Where

• Rapid Update Cycle (RUC)– Operational Version at NCEP

• Mesoscale Analysis and Prediction System (MAPS)– Experimental Version at NOAA/ERL/FSL

(Essentially the same software.

New capabilities tested first in MAPS at FSL)

RUC/MAPS Purpose

• Provide high-frequency mesoscale analyses and short-range forecasts for:– aviation– severe weather forecasting– forecasts for public– other transportation– agriculture

The 1-h Version of the RUC

Data cutoff - +20 min, 2nd run at +55 min at 0000, 1200 UTC

NCEP Operational ModelsModel Name of

RunDuration Freq. Domain Where Develop.

RUC RUC 12 hr 1 hr CONUS FSL/U. of Miami

Eta Eta 36/48 hr 6/9 hr N.Amer.+ NCEP/U. ofBelgrade

Global Spectral AVN 72 hr 6 hr Global NCEP

Global Spectral MRF 240 hr 24 hr Global NCEP

Coupled Seasons Global NCEP

Key Personnel -- RUC-2 Development/Implementation

Stan Benjamin Analysis/model dev, mgmt John Brown Model dev, parameterizationsKevin Brundage NCEP impl., WWW, graphicsDezso Devenyi 3-d VAR developmentGeorg Grell Model dev., parameterizationsBarry Schwartz Obs ingest, obs sensitivity studiesTanya Smirnova Land-sfc processesTracy Lorraine Smith Obs ingest, obs sensitivity studiesTom Schlatter Interaction w/ NCEP

Geoff Manikin NCEP liaison for RUC, impl.Geoff DiMego Interaction w/ NCEP/NCO, NWS

Uses of the RUC• Explicit Use of Short-Range Forecasts

– Aviation Weather Center - airmets, sigmets– Storm Prediction Center - severe weather watches– FAA– Dept. of Transportation - air traffic management– National Weather Service Forecast Offices– Airline Forecasting Offices– NASA Space Flight Centers

• Monitoring Current Conditions with Hourly Analyses

• Evaluating Trends of Longer-Range Models

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RUC1 vs RUC2 Characteristics

RUC-1 RUC-2Assimiliation 3 hr 1 hr, unified 3-d /surface cycle

Analysis OI - hybrid-b OI with new data, cycled cloudvariables, soil moisture, temp.,and snow cover

Model Hybrid-b, 60 km, 25levels

Hybrid-b/MM5, 40 km, 40levels, larger domain

MoistPhysics

Supersaturationremoval

Cloud microphysics (MM5) -explicit fcsts of cloud water, rainwater, snow, ice, graupel, numberconcentration - ice particles

RUC-1 versus RUC-2, cont.

RUC-1 RUC-2SurfaceProcesses

SFC fluxes (Pan) Sfc fluxes with multi-levelsoil/vegetation model with snowaccumulation/melting

Radiation Sfc energy budget,clouds = f(RH)

Full atmos. radiation - influencedby hydrometeors (MM5)

Turbulence Mellor - Yamadalevel 2.0

Level 3.0 (Burk-Thompson) withexplicit TKE forecast

Initialization Adiabatic digitalfilter

Digital filter with optimal filter

SurfaceConditions

Land use, SST -Clima. no snow cover

Improved land use, vegetationclass, daily SST/LST snow,cycled soil moisture/temp./snow

Hourly Data for 40 km MAPS/RUC-2

Data Type ~Number Freq. UseRawinsonde (inc. special obs) 80 / 12 h NCEP and FSL

WPDN/NPN profilers -405 MHz 31 / 1 h NCEP and FSLBoundary layer profilers -915 MHz 15 / 1 h FSL onlyRASS (WPDN + Bound.Layer 15 / 1 h FSL only

VAD (velocity azimuthdisplay) winds (WSR-88D) 110-130 / 1h NCEP and FSLAircraft (ACARS)(wind,temp) 700-2800 / 1 h NCEP and FSLSurface - land (wind,psfc,T,Td) 1500-1700 / 1 h NCEP and FSLBuoy 100-200 / 1 h NCEP and FSL

Yellow items new for RUC-2

**

**not used since 1/99pending QC issues

Hourly Data for 40 km MAPS/RUC-2, cont.

Data Type ~Number Freq. UseGOES precipitable water 1000-2500 / 1 h NCEP and FSLGOES high-density clouddrift winds (IR, VIS, WV cloud top) 1000-2500 / 3 h NCEP and FSLSSM/I precipitable water 1000-4000 / 2-6 h NCEP onlyShip reports 10s / 3 h NCEP onlyReconnaissancedropwinsonde a few / variable NCEP only

Yellow items new for RUC-2

Real-time observation counts at http://maps.fsl.noaa.gov for RUC-2 and 40-km MAPS

15

Advantages of Coords for Data Assimilation

Analysis- adaptive 3-d correlation structures and

analysis increments, esp. nearbaroclinic zones- improved coherence of obs near fronts for QCForecast Model- reduced vertical flux thru coordinate surfaces, leading to reduced vertical dispersion -- much of vertical motion implicit in 2-d horiz. Advection- conservation of potential vorticity- reduced spin-up problems (Johnson et al. 93 MWR)

Improvements due to the 1-hr cycle and earlier data cut-off time

RUC-2 Time Availability vs. RUC-1

RUC-2 Analysis

• QC - buddy check, removal of VADs w/ possible bird contamination problems

• 3-part analysis (all using optimal interpolation)1) univariate precipitable water (PW) analysis - using

satellite PW obs - update mixing ratio field

2) z/u/v 3-d multivariate analysis - update v based on height/thickness analysis increment, update psfc from

height increment at sfc, update u/v at all levels

RUC-2 Analysis, cont.

3) univariate analysis of condensation pressure at all levels, v at all levels. Also update u/v near sfc and psfc with univariate analysis with smaller correlation lengths

• Update soil temp at top 2 levels to maintain (Tskin - T1-

atmos)

• Pass through soil moisture, cloud mixing ratios, snow cover/temperature (will alter these fields at future time)

RUC-2 Analysis, cont.

• Vertical spreading (correlation of forecast error) based on potential temperature separation (not pressure separation as w/ other models)

• Analysis in generalized vertical coordinate (code applicable to pressure, sigma, or eta analysis) except for adjustment at end to reference potential temperatures and new psfc

• Background is usually previous 1 hr RUC forecast

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Raob sounding RUC2 sounding

Close fit to observations in RUC2 analysis

21

Raob RUC after fix RUC before fix

7 April 99 significant-level fix in RUC-2

RUCS 60 km Hourly Surface Analyses

• Draws fairly closely to data

• Persistence background field (1 hr previous analysis– some QC problems– no consistency with terrain

• MAPS sea-level pressure, (Benjamin & Miller, 1990 MWR)

• Blending to data-void region from NGM

Surface Analyses/Forecasts in RUC-2

• integrated with 3-d 40 km 1 hr cycle

• dynamic consistency with model forecast => accounts for:– land/water, mtn circulations, sea/lake breezes,

snow cover, vegetation…

• improved quality control - model forecast background prevents runaway bullseyes

• forecasts out to 12 hr in addition to hourly analyses

Surface Analyses/Forecasts in RUC-2, cont.

• Same fields as in 60 km RUCS, plus all fields available in 3-d system

RUC-2 sfc files (GRIB)

0.3 MB / output time

all variables from RUCS plus

precip

precip type

stability indices

RUC-2 use of surface dataAll winds, sfc pressure obs usedT/Td used if abs (Pstation - Pmodel) < 70 mb

- about 90% west of 105ºW, 99% east of 105ºWID Eta-48 Eta-29 RUC-40

FGZ 0* 18 10 (FLG)TUS 60 13* 44SLC 59* 68 59*MFR 109 48* 67OAK 18* 15* 25SAN 12 5* 23DRA 42 29* 34*GJT 98 105 65*RIW 104 27 16*GEG 4* 11 1*GTF 26 4* 14UIL 14* 9* 11*SLE 50 15* 22BOI 55 21* 24*

GGW 29 13 5*VBG 5* 32 3*

** w/I 5 mb of closest fit

|pmodel - pstn|

RUC-2 Model

• Prognostic variables– Dynamic - (Bleck and Benjamin, 93 MWR)

v, p between levels, u, v

– Moisture - (MM5 cloud microphysics)• q v, qc, qr, qi, qs, qg, Ni (no. conc. ice particles)

– Turbulence - (Burk-Thompson, US Navy, 89 JAS)– Soil - temperature, moisture - 6 levels (down to 3 m)– Snow - water equivalent depth, temperature

(soil/snow/veg model - Smirnova et al., 1997 MWR)

RUC-2 Model, cont.

• Numerics– Continuity equation

• flux-corrected transport (positive definite)

– Advection of v, all q (moisture) variables• Smolarkiewicz (1984) positive definite scheme

– Horizontal grid• Arakawa C

– Vertical grid• Non-staggered, generalized vertical coordinate currently set

as isentropic-sigma hybrid

RUC-2 Model, cont.

• Cumulus parameterization– Grell (Mon.Wea.Rev., 1993)– simplified (1-cloud) Arakawa-Schubert– includes effects of downdrafts

• Digital filter initialization (Lynch and Huang, 93 MWR)– +/- 40 min adiabatic run before each forecast

MM5 Level 4 Microphysics• Predicts mixing ratios of water vapor, cloud water, rain

water, cloud ice, snow, graupel and number concentration of cloud ice

• Ongoing improvements in collaboration with NCAR/RAP

• Continuous cycling of liquid and solid hydrometeors

• NCEP C-90 CPU usage (12 hr forecast):– 10% microphysics

– 15% advection of hydrometeors

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Montreal ice storm - 9h RUC2 forecast valid 2100 9 Jan 98.N-S cross sections of RUC2 microphysics

| YUL

31

RUCLand-surfaceProcessParameterization

(Smirnova et al.1997, MWR)

Ongoing cycleof soil moisture,soil temp, snowcover/depth/temp)

Fields From Soil/Snow Model• Soil temperature at 6 levels• Soil moisture at 6 levels• Surface runoff• Sub-surface runoff

• Direct evaporation from bare soil• Evapotranspiration• Evaporation of canopy water• Condensation of water• Canopy water• Water dripping from the canopy

Fields From Soil/Snow Model, cont.

• Snow depth• Snow temperature• Accumulation of snow• Amount of melted snow• Flux of snow phase change heat

– Predicted soil variables cycled since April 1996– Predicted snow variables cycled since March 1997

RUC - 2 Output Files

• Isobaric main (25 mb, 212 grid)– 6 3-d variables (ht, temp, RH, u/v, vv)– 80 2-d variables (prec, indices, spec. level, …)– ~7 MB / output time

• Surface fields (212 grid)– 25 2-d variables (p, T, TD, u/v, 3-h dp, precip,

indices…)– ~0.3 MB / output time

RUC - 2 Output Files, cont.

• 211 isobaric/sfc grids (will add vert. Vel.)

• BUFR hourly soundings - same format as Eta– ~290 stations– ~1.5 MB for 12-h fcst, all stations (week of 12/8/97)

• Native - – ~10 MB / output time

40 km MAPS versus 32 km Eta

Apr-Jul1998

40 km MAPS versus 32 km Eta, cont.

38

RUC vs. Eta - 12h fcsts - 7 April - 10 May 1999

Improvements in 40-km RUC-2over RUC-1

• Wind analyses/forecasts - improved skill at all times• Temperature - improved skill, much

reduced bias• RH - improved skill, much

reduced bias• Turbulence -

– sharp, coherent structures near frontal zones

Improvements in 40-km RUC-2

• Icing -– explicit microphysics with cloud water/rain/snow/ice/graupel

• Surface forecasts -– substantial improvement from addition of surface physics

(multi-level soil/vegetation model, snow physics), clouds, improved radiation

• Precipitation -– much better especially in orographic precip and heavy precip

events

Directions for Future RUC-2 Improvements

(suggested by precipitation verification)

• Improve cloud/moisture analysis. – Use of advanced microphysics in RUC-2 means that initial

cloud errors can lead to underforecasting. Work is underway to add satellite, radar and surface data to forecast cloud fields.

• Introduce fractional cloudiness into the model– Allow supersaturation at <100% RH within 40 km grid boxes

• Convective parameterization (Grell, includes effect of downdrafts)– Gives reasonable performance but still needs

tuning/improvement

Dec 98 change bundle for RUC-2

• Y2K fixes

• Analysis changes

– smaller horiz. error correlation near sfc for T/Td, slightly less dependence on stability => improved sfc T/Td fit in mtns

– fix to use of cloud drift winds => will have much more effect (over water only)

– better fit to sfc obs

• Model changes

– fixes to sfc physics - reduction of cool bias in daytime

– fixes to radiation - more cooling at night, slightly more heating in daytime

– less convective precip over warm water

Dec 98 change bundle for RUC-2, cont.

• Diagnostic fixes– CAPE/CIN - mix lowest 30-40 mb - less

jumpiness from analysis to 1h fcst– tropopause level fix

• GRIB table fixes– Allow soil cycling with adequate precision

• Boundary condition fix to account for Eta change in RH as of 11/3/98

Apr 99 emergency change for RUC2

• Correctly uses raob sig-level temp/dewpoint data now.

• Previously, missed sig-level T/Td data (TTBB) and forced in linearly interpolated structures between mandatory levels.

• Significant improvement in RUC grid sounding structures and in overall RUC performance

May 99 post-proc fixes for RUC2

• Bug/consistency fixes for diagnosis of sfc T/Td in RUC2. (fix to lapse rate range)

– Biases in west US for T/Td reduced, 2 °C 0

– s.d. temps over US from 2.0 1.4 °C

(verification against METAR obs)

• CAPE- searches lowest 300 mb, not 180 mb

• More smoothing of isobaric winds in lower troposphere, near tropopause

• Use of NESDIS ice field

• Much faster running of RUC - 10 procs for all runs

RUC-2 Weaknesses

• Still some precip spin-up problem, despite cycling of cloud/precip variables, esp. for light precip/overrunning (1-3 hr late)

• Fix: Add cloud analysis - 1999 - 1st version, allow for cloud at RH < 100%

• Too much precip over warm oceans, too little near SE coast in cold season

• Dec 98 fix package helped some - work underway on fixing tendencies input to Grell convective parameterization

• Daytime convective precip in summer too widespread

• Upcoming fix on tendencies input to Grell scheme

RUC-2 Weaknesses, cont.• Convective precip forecasts miss many small areas, underforecast peak amounts.

– Lower equitable threat score than Eta

– more detailed than Eta

• Too much graupel near 0ºC

• Fix: with 20-km RUC, collaboration with FSL and NCAR on microphysics fixes

• Diurnal cycle of surface temperature a little too weak

– a little too warm at night

• Dec 98 fix package - sfc flux change, radiation fix, GRIB precision to allow proper soil moisture cycling

• May 99 fix - improve diagnosis of sfc temp/Td diagnosis -- significant reduction in bias

RUC-2 Weaknesses, cont.

• Detailed (noisy?) output compared to other models, especially vertical velocity

– Detail is probably realistic over terrain

• Analysis near coastlines

– does not account for land/sea contrast

– analysis increments over coast extrapolated over sea

Fix: Account for lower horizontal correlation in analysis when crossing coastline

Fixed RUC-2 Weaknesses• Analysis sounding structure

– irregular near ground if only sfc data assimilated

Fix: analysis tuning (Dec 98)

Fix: sig-level bug fix (Apr 99) *****************

• CAPE/CIN

– analysis values previously too high in high CAPE areas

– jump between analysis and 1-h forecasts

Fix: CAPE software (Dec 98)

(May 99 - parcel search now in lowest 300 mb, not 180 mb layer)

RUC-2 Strengths• Surface fields, esp. surface winds

– sfc files• analysis and forecast

• small

• standard sfc fields plus precip, stability, precip type

• Topographically induced circulations– sea/lake breezes (scale too large but they’re there)– mtn/valley circulations– differential friction effects

RUC-2 Strengths, cont.• Precipitation fields

– more detailed than Eta (lower FAR but lower POD)

• Snow accumulation– explicit, not diagnosed (from MM5 microphysics)

• Precip. type– uses explicit hydrometeor mixing ratios/fall rates

• Upper-level features– hybrid / coordinate– winds, PV, temps, fronts, more coherent vorticity

structures on isobaric surfaces

RUC-2 Strengths, cont.• Lower tropospheric temp/RH

– good fcst sounding structure (esp. after 4/99 fix)

– hybrid coordinate

• Soil/hydro fields

– soil moisture - cycled in 6-level soil model

– surface runoff, canopy water, dew formation, etc.

• Vertical velocity

– available in RUC-2

– good mtn wave depiction, frontal features

• Hourly analyses

– available much sooner than RUC-1 grids

– (4/99 speed-up in RUC processing at NCEP, 12h fcsts available 30 min sooner, analyses available 8-10 min sooner)

RUC/MAPS Web Resources

• Main RUC/MAPS home page– http://maps.fsl.noaa.gov

• RUC2 discussion forum– maps.fsl.noaa.gov/forum/eval

• RUC2 real-time data inventory– maps.fsl.noaa.gov/final.ruc_data.html

• RUC2 Tech. Proc. Bulletin– maps.fsl.noaa.gov/ruc2.tpb.html

RUC/MAPS Web Resources, cont.

• RUC-2 diagnosed variables - explanation of each

– maps.fsl.noaa.gov/vartxt.cgi

• RUC-2 evaluation from Nov 97 - Jan 98 field test

– maps.fsl.noaa.gov/ruc2.evalsum.html

• Experimental 36h fcsts run at FSL

• Parallel cycle w/ latest experiments (e.g., cloud analysis)

• AFDs/SFDs using RUC (http://maps.fsl.noaa.gov/sfd)– used to monitor NWS use of RUC

The Future of the RUC

• Transfer of current 40km RUC2 to IBM SP-2 - July 1999– faster, distributed post-processing

• 20 km 1 hr version on IBM SP-2– Probably in early 2000– 3-d variational analysis– Cloud/hydrometeor analysis using satellite, radar, surface,

aircraft combined with explicit cloud fcsts in RUC-2• Later, assimilation of new data sets: sat. cloudy/clear

radiances (GOES/POES), hourly precipitation analyses, WSR-88D radial winds, lightning, GPS precipitable water, sat water vapor winds

The Future of the RUC, cont.

– Improved physical parameterizations, including cloud microphysics (freezing drizzle), surface physics (frozen soil, high-resolution soil and surface data sets), and turbulence physics

• Higher resolution versions

– 15-20 km/60 level - expanded domain - early 2001

– trade-off between resolution and domain?

57

20km RUCtopography

- early 2000

58

The Future of the RUC, cont.• Non-hydrostatic -z model under development

– Generalized vertical coordinate– Nudging of coordinate surfaces toward “grid generator”

• can be set as smoothed quasi-isentropic hybrid coordinate – treats sub~20km variations (convective clouds, breaking mountain waves)

w/ quasi-horizontal coordinates

– treats >20km variations w/ -z coordinates

– Collaboration between University of Miami (Rainer Bleck, Zuwen He), FSL (John Brown, Stan Benjamin), and NCAR (Bill Skamarock)

– Part of WRF model (Weather Research and Forecast - NCAR/FSL/NCEP/CAPS) effort - a generalized vertical coordinate option.

– WRF-based RUC probably by 2005-6 at 5-10km scale– 30-min cycle or finer?

Feedback

• Send feedback/questions on RUC performance to the RUC discussion forum.

• Invite us to workshops.

http://maps.fsl.noaa.gov/forum/eval

303-497-6387

benjamin@fsl.noaa.gov