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Operational Use of the Rapid Update Cycle

Operational Use of the Rapid Update Cycle. Stan Benjamin - NOAA/FSL benjamin@fsl.noaa.gov http://maps.fsl.noaa.gov - RUC/MAPS web page. COMAP Symposium 16 December 1999. The 1-h Version of the RUC. Data cutoff - +20 min, 2nd run at +55 min at 0000, 1200 UTC. RUC/MAPS Purpose.

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Operational Use of the Rapid Update Cycle

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  1. Operational Use of the Rapid Update Cycle Stan Benjamin - NOAA/FSL benjamin@fsl.noaa.gov http://maps.fsl.noaa.gov - RUC/MAPS web page COMAP Symposium 16 December 1999

  2. The 1-h Version of the RUC Data cutoff - +20 min, 2nd run at +55 min at 0000, 1200 UTC

  3. RUC/MAPS Purpose • Provide high-frequency mesoscale analyses and short-range numerical forecasts for users including: • aviation • severe weather forecasting • general public forecasting • other transportation • agriculture

  4. 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)

  5. Uses of the RUC • Explicit Use of Short-Range Forecasts • Monitoring Current Conditions with Hourly Analyses • Evaluating Trends of Longer-Range Models Some places where the RUC is used • Aviation Weather Center - airmets, sigmets • Storm Prediction Center - severe weather watches • FAA – CWSUs, WARP, air traffic management (CTAS), ITWS.. • National Weather Service Forecast Offices • Airline Forecasting Offices • NASA Space Flight Centers • Private vendors

  6. NWS Forecast Discussion Use of RUC - Feb-Nov 1999 100-400 40-99 20-39 10-19

  7. http://maps.fsl.noaa.gov

  8. Hourly Data for 40 km MAPS/RUC-2 Data Type ~Number Freq. Use Rawinsonde (inc. special obs) 80 /12h NCEP and FSL WPDN/NPN profilers 31 / 1h NCEP and FSL - 405 MHz Boundary layer profilers 15 / 1h FSL only RASS (WPDN and PBL) 15 / 1h FSL only VAD winds (WSR-88D) 110-130 / 1h **NCEP & FSL Aircraft (ACARS)(V,temp) 700-3000 / 1h NCEP and FSL Surface - land (V,psfc,T,Td) 1500-1700 / 1h NCEP and FSL Buoy 100-200 / 1h NCEP and FSL **not used since 1/99 in RUC or EDAS pending QC issues Yellow items new for RUC-2

  9. Hourly Data for 40 km MAPS/RUC-2 (cont). Data Type ~Number Freq. Use GOES precipitable water 1000-2500 / 1h NCEP and FSL GOES high-density cloud drift winds (IR, VIS, WV cloud top) 1000-2500 / 3h NCEP and FSL SSM/I precipitable water 1000-4000 /2-6h NCEP only Ship reports 10s / 3h NCEP only Reconnaissance dropwinsonde 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

  10. Advantages of q Coords for Data Assimilation Analysis - adaptive 3-d correlation structures and analysis increments, esp. nearbaroclinic zones - improved coherence of observations near fronts for QC Forecast Model - reduced vertical flux through 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)

  11. RUC hybrid-b levels - cross-section Hybrid-b levels - solid q levels (every 6 K) - dashed No discontinuities at q/stransitions

  12. Effect of vertical coordinate on frontal features Turbulence diagnostic at FL200 (20,000 ft) - calculated from native grid from both MesoEta and RUC (matched forecast times) Sharper frontal resolution with RUC despite coarser horizontal resolution and fewer vertical levels

  13. Rapid Update Cycle – Present and Next Version 1999 Operations 2000-01 Operations Resolution 40 km, 40 q/s levels 2015 km, 40  50-60 q/s levels Analysis Optimal interpolation on 3-d variational technique on generalized on generalized q/s surfaces q/s surfaces, hydrometeor analysis w/ GOES…, use raw instead of interp. obs Assimilation Intermittent 1-h cycle Intermittent 1-h cycle Stable clouds Mixed-phase cloud microphysics MM5), Improved microphysics, /precipitation explicit fcst of cloud water, rain water, addition of drizzle snow, ice, graupel, no. concentration of ice particles Sub-grid-scale Grell (1993) Modified Grell, scale dependence, precipitation shallow convection, interaction w/ cloud microphysics Turbulence Burk-Thompson explicit TKE scheme Refined Burk-Thompson or e- Radiation MM5 LW/SW scheme, f(hydrometeors) Refined MM5 scheme Land-sfc processes 6-level soil/veg model (Smirnova, Add vertical soil type variability, 1997, 1999) w/ frozen soil, 2-layer snow improved cold season processes Sfc conditions Daily 50km SST/14 km LST, Combine sat Tskin, use 3-d soil type 0.14 monthly NDVI veg frac, cycled soil moisture/temp, snow depth/temp

  14. RUC-2 Analysis • Background (1-h fcst usually) subtracted from all obs • Analysis is of forecast error • 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 analysis increment at sfc • update u/v at all levels • Partial geostrophic balance – vertically dependent, weakest at surface

  15. RUC-2 Analysis, cont. - 3) univariate analyses • condensation pressure at all levels • v at all levels • update u/v near sfc and psfc (univariate analysis) with smaller correlation lengths • Pass through soil moisture, cloud mixing ratios, snow cover/temperature (will alter these fields in future, cloud analysis parallel cycle now running)

  16. 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

  17. Raob sounding RUC2 grid sounding Close fit to observations in RUC2 analysis

  18. Raob RUC after fix RUC before fix 7 April 99 significant-level fix in RUC-2

  19. Use of ‘minimum topography’for 2m T/Td fields from RUC2 RUC2 2m T/Td fields are not valid at model terrain surface Instead, they are derived from model surface fields and lapse rates in lowest 25 mb to estimate new values using a different topography field that more closely matches actual METAR elevations “Minimum topography” – minimum 10km value inside each 40km grid box, then updated with high-resolution analysis using actual METAR elevations.

  20. RUC2 topography fields Minimum topo for 2m T/Td Model topo

  21. RUCS 60 km Hourly Surface Analyses (same as AWIPS MSAS) • Draws fairly closely to data • Persistence background field (1 hr previous analysis • QC vulnerable to consistent data problems • no consistency with terrain effects except as reflected in observations • MAPS sea-level pressure, (Benjamin & Miller, 1990 MWR) • Blending to data-void region from NGM

  22. 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

  23. Divergence - 0900 UTC 20 Jan 98 (blue - conv, green/yellow - div) RUC2 Surface Analysis Topographical features more evident with model background RUCS 60km surface analysis Little consistency with nighttime drainage

  24. Divergence - RUC2 Surface Analysis - 0600Z 19 April 96 Consistency with topographical features in model (land/water roughness length variations in this case)

  25. 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

  26. RUC-2 use of surface data All winds, sfc pressure obs used T/Td used if abs (Pstation - Pmodel) < 70 mb - about 90% west of 105ºW, 99% east of 105ºW Eta48 Eta29 RUC40 FGZ 0 18 10 TUS 60 13 44 SLC 59 68 59 MFR 109 48 67 OAK 1815 25 SAN 12 5 23 DRA 42 29 34 GJT 98 105 65 RIW 104 27 16 GEG 4 11 1 GTF 26 4 14 UIL 14 9 11 SLE 50 15 22 BOI 55 21 24 GGW 29 13 5 VBG 5 32 3 |pmodel - pstn| ** within 5 mb of closest fit

  27. RUC surface temperature forecasts - verification against all METARs in RUC domain Excellent analysis fit to surface obs (also wind, Td) 3-h forecast better than 3-h persistence RMS error Bias (obs - forecast) persistence Validation time Validation time

  28. Effect of 6 May 1999 Fix to surface temperature diagnosis in RUC2 Improved lapse rates in extrapolation from RUC2 model terrain to different terrain file (“minimum topography”) used for sfc T/Td diagnosis.

  29. -3 -2 -1 0 1 2 3 4 5 g/kg Sfc virtual pot temp Sfc water vapor mix ratio Analysis increment fields (1h forecast error correction) RUC analysis 2200 UTC 29 Oct 1999

  30. Wind analysis increment fields (forecast error correction) - RUC analysis 2200 UTC 29 Oct 1999

  31. SLC CYS Vertical cross-section – 2200 UTC 29 Oct 99 RUC 3-d analysis Need for 3-d consistency to initialize model, other diagnostics

  32. 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)

  33. 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

  34. RUC-2 Model, cont. • Cumulus parameterization • Grell (Mon.Wea.Rev., 1993) • simplified (1-cloud) version of Arakawa-Schubert • includes effects of downdrafts • Digital filter initialization (Lynch and Huang, 93 MWR) • +/- 40 min adiabatic run before each forecast

  35. RUC Digital Filter Initialization 40 Dt forward 40 Dt backward - digital filter avg of model values Produces much smoother 1-h fcst Mean absolute sfc pres tendency each Dt in successive RUC runs

  36. Processes in RUC2/MM5 microphysics (Reisner, Rasmusssen, Bruintjes, 1998, QJRMS)

  37. RUC2 case study - Quebec/New England ice storm - 9 Jan 1998 500 mb height/vorticity - 9h RUC2 fcst valid 2100 UTC

  38. RUC2 9h fcst - Surface temp (image), MSLP (beige isobars)

  39. N-S cross-section - temperature (isopleths, int = 2 deg C, solid for > 0) RH (image), 9h RUC2 forecast YUL

  40. Montreal ice storm - 9h RUC2 forecast valid 2100 9 Jan 98. N-S cross sections of RUC2 microphysics Water vapor mixing ratio / q Cloud water mixing ratio | YUL/Montreal Graupel mixing ratio Rain water mixing ratio

  41. 40 km RUC versus 32 km Eta June-July 1999

  42. 40 km RUC versus 32 km Eta June-July 1999

  43. RUC vs. Eta 12-h fcsts 250mb RMS vector error 12 11 10 9 8 7 6 5 From 80km grids for both models RUC uses 24h Eta for lateral boundary conditions Comparable skill, potential for ensembles

  44. RUC 1, 3, 6, 12h forecasts valid at same time (against 0000 and 1200 UTC rawinsonde data) Better wind and temperature forecasts with use of more recent asynoptic data

  45. RUC/MAPS Land-surface Process Parameterization (Smirnova et al. 1997, MWR; 1999, JGR) Ongoing cycle of soil moisture, soil temp, snow cover/depth/temp) 2-layer snow model

  46. Previous MAPS vegetation New vegetation – BATS classes Addition of high-resolution EOS vegetation-type data to current 40km MAPS - September 1999

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