5-km WRF BMJ NWS-NCSU CSTAR VISITVIEW PRESENTATION 12 November 2004

An Operational Introduction to the Weather Research & Forecasting (WRF) Modeling System
5-km WRF BMJ NWS-NCSU CSTAR VISITVIEW PRESENTATION 12 November 2004 (updated) RFC 10-km analysis 5-km WRF explicit Gary Lackmann, NCSU With contributions from Michael Brennan, Stephen Jascourt, Jeff Waldstreicher, Kelly Mahoney, David Novak, Steven Koch, Wei Wang, WRF Tutorial Class & others 1

Outline A. WRF Overview B. DTC WRF Winter Forecast Experiment (DWFE)
1.) WRF implementation plans 2.) WRF modeling system overview 3.) What is different? What is better? B. DTC WRF Winter Forecast Experiment (DWFE) 1.) Objectives of experiment 2.) Domain and design 3.) Differences C. Examples and Implications: What to Look For 1.) Convection and resolution 2.) Cold-air damming case study 2

Objectives: Provide a basic understanding of the WRF modeling system and what distinguishes it from existing models Outline the basic configuration of the DTC WRF Winter Forecast Experiment (DWFE) for this winter Discuss implications of high-resolution model runs in which a convective parameterization (CP) scheme is not used Examples of 5-km QPF for convective case Comparison of CP-scheme runs to explicit runs at 5 km Discuss model representation of a familiar cold-air damming event (5-km WRF with various physics options) 3

1.) WRF implementation Plans Courtesy of Stephen Jascourt, COMET, updated information 11/2004
Feb(?) 2005: final Eta upgrade package Some changes (high-res veg, soil data) already in NMM-WRF Other changes (radiation?, physics, use radar & surface temps) Early 2006 (?): WRF-NMM replaces Eta Eta look-alike grids, substitutes for Eta in “Eta” MOS 10-km grid spacing AWIPS labels to still say “Eta” & “Meso” until OB6 Implementation date not “set in stone”, evidently WRF-NMM to be implemented early 2006 will be configured somewhat consistently with Eta it will replace: NOAH LSM NCEP microphysics BMJ CP scheme The version of WRF to replace the Eta model is called the North American Mesoscale WRF. In preparation for its launch, a WRF ensemble will be run using initial and boundary conditions from the Eta model. You are strongly urged to gain familiarity with the model by watching its forecast on the web page cited here. The computer upgrade referred to is expected to be completed in January 2005. The Eta model will undergo one last set of changes, in early Some of these changes are already in the NMM-WRF. Some are not but will be put in by the time the WRF replaces Eta. Changes to the land surface physics being tested presently show a pronounced wet bias, in contrast to the current Eta model dry bias. Other changes included in the package may compensate somewhat. The overall result may be large changes in the characteristics of precipitation and other sensible weather, more obvious than the changes from the transition to WRF. The North American Mesoscale WRF, with a domain similar to the Eta model domain and a grid spacing of 10 km, will replaces the Eta in fall Its assimilation cycle will use analyses produced by a new 3d-var presently being tested in the GFS. The new analysis, the Grid-point Statistical Interpolation, will first replace the Spectral Statistical Interpolation now used in the GFS. Beware that some products may still have legacy labels. If the label refers to the Eta model, the product will actually come from WRF. As a rough gauge on what the future holds, by around 2010 give or take a year or two, the model will be running at 5 km grid spacing, probably still using a convective parameterization, and the principal advances will likely have come from assimilating observations from the next generation of satellite instruments and from related radiative and microphysical use of aerosol data. Information on this slide and the next slide was vetted by Geoff DiMego, Chief, Mesoscale Modeling Branch, Environmental Modeling Center, NCEP on August 17, 2004. A1

1.) WRF implementation Plans at NCEP Slide courtesy of Stephen Jascourt, COMET
Rapid Refresh WRF (replaces RUC) 2007 likely. 10-km grid spacing 2010?: 8-km grid spacing Hurricane WRF 2006 likely 2010?: 7-km grid spacing and coupled ocean model Ensemble WRF 2007: replace SREF 2010?: 25 members at 12-km grid spacing WRF Hi-Res Window (nested, regional domain) 2010?: 3- or 4-km grid spacing with explicit convection Other WRF models planned for NCEP implementation are shown here. Projections for 2010 are estimates, not hard targets. A2

2.) WRF Modeling System Overview
WRF isn’t “just a model”; it is a versatile modeling system, including: A graphical interface for grid configuration and initialization (Standard Initialization, WRFSI) A highly organized, layered model architecture with highly accurate numerics (less diffusion needed) Data assimilation system (WRF 3DVAR) Idealized modeling capabilities A unique set of graphical tools Image from Shu-Hua Chen’s Tutorial presentation A3

GEMPAK A4

Terminology: WRF is not a single model… it can be configured in a multitude of different ways WRF has two different “dynamical cores”… but what the heck is a “dynamical core”? “Dynamical core”: nuts & bolts of a model Finite differencing schemes (a.k.a. “numerics”) Vertical coordinate, grid geometry A5

2 “dynamical cores”: Nonhydrostatic Mesoscale Model (NMM) core was developed at NCEP (WRF-NMM) NCAR developed another core, known as Advanced Research WRF (ARW) This was previously referred to as the “Eulerian mass (EM) core”, or sometimes as the “NCAR” core A6

The Development Testbed Center (DTC) WRF experiment will include both dynamical cores; results may vary substantially WRF-EM WRF-NMM A7

Hypothetical conversation among forecasters: A: “Did you see what the 12Z Eta is doing with that coastal system? Much different than the GFS result.” A8

Hypothetical conversation among forecasters: A: “Did you see what the 12Z Eta is doing with that coastal system? Much different than the GFS result.” B: “How does the WRF model do with this kind of system?” A9

Hypothetical conversation among forecasters: A: “Did you see what the 12Z Eta is doing with that coastal system? Much different than the GFS result.” B: “How does the WRF model do with this kind of system?” The latter comment is not meaningful, because “WRF” comes in many flavors, and can be many different things! A10

3.) What is Different? What is Better?
WRF designed so that model configurations can be changed and interchanged easily WRF makes it easy to: create new model components share parameterizations efficiently transfer research findings to operations NCEP mixed KF CP Kessler MP NMM core BMJ Purdue-Lin PBL, etc Grell EM core This slide is weird… Ferrier MP Explicit Etc… A11

3.) What is Different? What is Better?
By bringing everyone into same modeling environment, WRF will bridge gap between research and operations WRF both promotes and facilitates ensemble forecasts Experimental WRF run This slide has issues too… Ensemble forecast A12

B. THE DTC WRF FORECAST EXPERIMENT
With contributions from Jeff Waldstreicher, Steven Koch, and others (updated 11/2004) B1

DTC Winter Forecast Experiment (DWFE)
Two primary operational objectives: Compare Eta-12 to WRF run at 5 km grid spacing with explicit convection (no CP scheme) over CONUS Expose forecasters to future WRF capabilities Two primary research objectives: Determine if encouraging 4-km BAMEX WRF runs (summer 03, 04) provide forecast value during winter, longer lead times (~48h) Determine extent to which gravity waves, lake-effect snow, CAD, coastal fronts, etc. can be skillfully forecast B2

DTC Winter Forecast Experiment
Run 2 different versions of WRF in real time 2 Different Dynamical Cores (NMM & ARW) 2 Different Physics Packages (NCEP & NCAR) Explicit Convection (run without CP scheme) Initial conditions – 00Z EDAS for both runs Boundary conditions – 00Z Operational Eta Run at 00Z, out to 48 hours Runs complete with data to field offices by ~1400Z B3

Run 1: ARW, NCAR Physics Suite NOAH 5-layer land-surface model (LSM) WSM 5-class microphysics No cumulus parameterization Yong-Sei University (YSU) PBL Dudhia shortwave RRTM longwave Run 2: WRF-NMM, NCEP Physics Suite Ferrier microphysics (as in Eta) Mellor-Yamada-Janjic 2.5 PBL (as in Eta) Eta (Lacis-Hansen shortwave) Eta (Fels-Schwartzkopf longwave) B4

Real-Time Verification Web Page Forecaster Feedback – Web Form Jump-start WRF Training Activities For SE CSTAR group: phenomenological evaluations: CAD, coastal fronts winter weather, etc. QPF events handling of upstream convection B5

Domain map Sufficient coverage of Gulf of Mexico, Gulf Stream
5-km grid spacing, 38 vertical levels B6

Vertical Level Distribution
Higher lower-tropospheric resolution to handle CAD B7

DWFE WRF Data Dissemination Plans
FX-NET Used successfully by IMETs Servers at FSL – Java Clients on WFO/RFC PCs Gives Nearly Full D2D Functionality (OB3.3) Can utilize full 3-D data set Cross-sections and Time-Height displays Soundings Access to both WRF runs (as well as other models) Can set up color tables and procedures 3-hour data time intervals minimum (possibly 1-hour) B8

FX-NET Screen Capture B10

AWIPS GRIDS Only WRF-NMM Limited set of fields to support GFE Use e.g., 2-m T/Td, 10-m Wind, QPF etc… Grid List not Finalized University Partners (& HPC?) receive more complete data Data Archive at NCAR Web Graphics BUFR Soundings (Hopefully, not confirmed) B9

Operational Usage of DTC WRF:
How should NWS forecasters use DTC WRF information this winter? It is experimental… no certainty regarding performance (although we have our hopes :-) Will be there so forecasters "can use" it - at their discretion of course If it emerges as a reliable tool, then it is another potential useful tool/resource The (A) purpose of experiment is to assess it - is it/could it be useful? B11

AWIPS GRIDS Only WRF-NMM Limited set of fields to support GFE Use 5 km / 3-hourly Resolution Sub-sector “tiles” to be sent via LDM University Partners (and likely HPC) to receive more complete set of grids (Ligia Bernardet) Data Archive at NCAR PROPOSED AWIPS GRIDS Surface Grids Sea Level Pressure & Model Surface Pressure 2 meter T and RH 10 meter Winds QPF (3 hour accumulation) Post-Processed Grids Total Instantaneous Cloud Cover Surface-based Lifted Index Precip type Constant Pressure Level Grids Height – 1000/850/700/500/250 mb Temp – 850/700/500 mb RH – 850/700/500 mb Wind – 850/700/500/250 mb Omega – 700 mb

C. Examples and Implications: What to Look For
Big contributions here from Mike Brennan (NCSU), and Wendy Sellers (NWS MRY, formerly NCSU) C1

Biggest differences between current Eta and WRF Experiment: 1.) [EXPLICIT convection]!! 2.) higher resolution (5-km grid spacing) 3.) non-hydrostatic C2

Perhaps the biggest change will be that these runs will have *explicit convection* C3

Explicit vs. Implicit Convection Issues
Some have shown for model grid spacing ~4 km or less, explicit gridscale motions adequately represent convective systems (e.g., Weisman et al. 1997) However, more work needed, including studies of a wide variety of convective systems, in order to establish the adequacy of this approach at 4-5 km. To provide a feel for what this change will mean in terms of model output during convective situations, we present model comparisons for a randomly selected warm-season convective case C4

C. 1.) WRF 5-km Forecast (NCSU)
Random “convective day”: 17 July 2004 WRF initialized with Eta analysis at 00 UTC Run out to 24 hours 5-km horizontal grid spacing with domain covering eastern CONUS Model physics Lin et al. bulk microphysics YSU boundary layer scheme Tested sensitivity to CP scheme choice (3 runs) BMJ cumulus scheme KF cumulus scheme Explicit (no cumulus scheme) C5

C. 1.) WRF 5-km Forecast (NCSU)
Two purposes here: 1.) Provide example of hi-res (5-km) model output, level of detail with convection 2.) Compare differences between BMJ & KF CP scheme and against no-CP (explicit) runs at same grid spacing as DWFE CAVEAT: This was a summer convective case, with organized winter convection we can hopefully expect better results C7

Synoptic Pattern 17 July 12Z

Synoptic Pattern 18 July 00Z

Eta 24-h Precipitation Forecast ending 00 UTC 18 July
Eta Total C10

WRF run, 5-km grid, BMJ CP scheme, Total Precipitation (
WRF run, 5-km grid, BMJ CP scheme, Total Precipitation (.in), same 24-h forecast WRF BMJ 5-km 24-h Total C11

WRF run, 5-km grid, Kain-Fritsch (KF) CP scheme, Total Precipitation (
WRF run, 5-km grid, Kain-Fritsch (KF) CP scheme, Total Precipitation (.in) WRF KF 5-km 24-h Total C12

Summary: BMJ vs KF Both KF and BMJ runs: most precipitation comes from CP schemes in this event, even with 5 km grid spacing More detailed structure in KF convective scheme precipitation relative to BMJ, different breakdown (typical) BMJ KF C13

Summary: BMJ vs KF Some significant differences in location of maxima, minima (e.g., western TN) How will the character of these fields compare to an explicit run (without CP scheme)? BMJ KF C14

WRF run, 5-km grid, EXPLICIT (no CP scheme) Total Precipitation (.in)
WRF EXPLICIT 5-km 24-h (grid-scale only) C15

24-h Total Precipitation Comparison
BMJ KF Note similarity of Eta, WRF-BMJ EXP Eta 211 C16

But what *really* happened?
Next, compare 6-h totals (18 Z – 00 Z), observations C17

6-h Precipitation Comparison (18Z 17th – 00Z 18th )
BMJ KF EXP RFC 10-km analysis C18

6-h Precipitation Comparison (18Z 17th – 00Z 18th )
BMJ Eta 218 EXP RFC 10-km analysis C19

NPVU - RFC Data Archive - Quantitative Precipitation Estimates C20

Comparison: 5-km KF, BMJ, EXP
Major differences in total precipitation between runs Heaviest precipitation in explicit run KF and BMJ schemes very active, even at 5-km grid spacing All 3 runs place precipitation maxima in different locations None of runs captured heavy showers over N. NC… C21

C. 2.) CAD Sensitivity Tests
5-km domain centered on Carolinas Run with BMJ, KF, and no CP scheme YSU PBL scheme Initialized at 12 Z 29 October 2002 Same CSTAR event shown previously (Wendy Sellers’ thesis case) Image: CAD erosion happening, photo: GL C22

Case Study: October 00 UTC 30 Oct 2002 C23

12 UTC 30 Oct 2002 C24

00 UTC 31 Oct 2002 C25

Premature CAD Erosion in Eta Forecast
GSO winds: Lighter, left Eta forecast winds: Bold, right Eta Model 36-h forecast sounding (dashed) GSO RAOB (solid) 00Z 31 Oct 2002 C26 2

Could BMJ Shallow Mixing Scheme be CAD Killing Culprit?
Hypothesis: Shallow mixing in model CP scheme is responsible To test, conducted workstation Eta simulations: 1.) Control run, similar to operational Eta 2.) Experimental run with shallow convective portion of BMJ scheme turned off, all else identical C27

Control vs. No-Shallow Eta
Shallow convection “smoking gun” footprint Instructor notes There is a lot of information in the left portion of the graphic related to how the BMJ scheme acts on the initial model profile. The original model sounding lines are dashed, the final sounding lines are shown in bright solid green and red. The right panel shows what the profile looks like at that point an hour later while the scheme has continued to be active. It may be worthwhile to discuss how often this sounding profile is observed in precipitating areas in the Eta model. Without shallow mixing scheme, stratus deck holds! C28

Eta run killed stratus… Will WRF 5-km run do the same?
Visible Satellite and Surface Observations Eta run killed stratus… Will WRF 5-km run do the same? 18 UTC 30 Oct 2002 C29

WRF Experiments Questions: How will WRF handle this event?
How does new YSU PBL scheme handle CAD? [Will WRF BMJ shallow mixing do the same thing at 5 km as operational Eta does at 12? (not relevant to DWFE though, but perhaps for WRF-NMM implementation)] C30

36-h forecast valid 00 UTC 31 October 2002 Red/Green GSO raob Blue (5-km WRF, EXP, MY PBL scheme)

Explicit Run 11Z 30 October 36-h forecast valid 00 UTC 31 October 2002 Red/Green GSO raob Blue (5-km WRF, EXP, YSU PBL scheme) C32

Explicit Run 11Z 30 October 36-h forecast valid 00 UTC 31 October 2002 Red/Green GSO raob Blue (5-km WRF, EXP, YSU PBL scheme) Yellow (5-km WRF, EXP, MY PBL scheme) C33

WRF 10-m wind and 2-m Temp, 36-h forecast valid 00 UTC 31 October 2002: MY PBL RUN

WRF 10-m wind and 2-m Temp, 36-h forecast valid 00 UTC 31 October 2002: YSU PBL RUN

Comparison of 5-km WRF runs
There is a moist shallow mixing component in the new YSU scheme This scheme is based on the MRF scheme, which was aggressive with CAD erosion previously Expect earlier CAD erosion in runs with YSU PBL scheme MY PBL Scheme YSU PBL Scheme C36

Interestingly, MM5 with Blackadar PBL scheme performed very well for this event…
33-h forecasts, valid 21 UTC 30 Oct 2002 MM5 Control Run: Red/Green Low Albedo Run: Blue Eta Operational Run: Yellow C37

Summary of CAD handling w/ WRF
Results are sensitive to choice of PBL scheme YSU mixes more aggressively… wipes out CAD too soon for this case and this model configuration In EXP runs of WRF in DWFE, no BMJ shallow mixing problems, but will YSU scheme be consistently more aggressive with CAD erosion? Need to study relative differences between BMJ shallow mixing and PBL issues in WRF at high-resolution Need to look at more cases! C38

Squall line placement, 31 Dec. 2002
12Z Radar MM5 3h precip ending 18Z 18Z Radar WRF 3h precip ending 18Z Even at same grid spacing (20km), WRF resolves structure of convection more accurately than MM5, still slow

Overall Summary WRF is an extremely versatile modeling system and there is no single “WRF” The DTC WRF Winter Forecast Experiment (DWFE) will provide a set of WRF runs once a day and will allow forecasters to gain an appreciation for WRF capabilities This experiment will be run without a CP scheme, which implies more structured and possibly heavier precipitation in some situations For CAD, we still need to learn more about the character of the new PBL schemes, but BMJ shallow mixing won’t be a problem for the winter experiment runs C39

Overall Summary Examples shown here are not intended to be representative or comprehensive summaries of WRF performance Prolonged scrutiny of WRF output for variety of cases and model configurations will be required for forecasters to gain a feel for reliability, capability, optimum configurations Much additional research will be required to establish optimum configurations for different phenomena C40

Acknowledgements Michael Brennan (NCSU grad student contributed model runs and graphics… if I were you I would hire him when he graduates, supported on CSTAR grant) Stephen Jascourt (Utilized some graphics from other talk, info on implementation) Jeff Waldstreicher, David Novak, NWS ER HQ (for info slides on implementation and DWFE) Wei Wang, and others at WRF Tutorial Class Kelly Mahoney (NCSU grad student, contributed several slides, supported on CSTAR grant) NWS Jonathan Blaes (RAH), Kermit Keeter (RAH) Matt Pyle (NCEP) for initial, BC data for CAD case NCEP – Brad Ferrier, Geoff Manikin, Geoff DiMego Steve Koch and others at DWFE for inviting us to participate in this experiment NOAA CSTAR grant NA03NWS468007 C41

Thank you!

WRF system includes graphical interface for model grid configuration and initialization (WRF Standard Initialization, WRFSI) Set up model domain with click of a mouse, pull-down menus, and more Initialize with a wide variety of data Much easier than with MM5! Implications for local NWS modeling efforts A6

Total (48h) precip Dec 31 2002 -Jan 1 2003 20-km grid spacing
Cold Season Convective Representation: WRF vs. MM5 for 31 December 2002 WRF (20km) Eta Analysis (onshore) Total (48h) precip Dec Jan 20-km grid spacing Heavy rain over FL (southern end of squall line) better handled in WRF run, but still too heavy to North

5-km WRF BMJ NWS-NCSU CSTAR VISITVIEW PRESENTATION 12 November 2004

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