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					GLFE Real-time TAMDAR Impact
Experiments with the 20km RUC


 Stan Benjamin,Tracy Lorraine Smith,
    Bill Moninger, Brian Jamison
   NOAA Forecast Systems Laboratory
             Boulder, CO
Outline of talk

Part 1:

General description of RUC 1h cycle
 - Data assimilated
 - Spatial effects of assimilated data
Recent enhancements to RUC assimilation

Previous results from RUC data impact experiments
Design of RUC parallel experiments – Dev / Dev2

Examples of Dev/Dev2 difference fields (Brian Jamison)

Part 2:
Actual statistical results
  Purpose for Rapid Update Cycle
  (RUC) model run operationally
             at NCEP
• Provide high-frequency mesoscale analyses,
  short-range model forecasts
• Use all available observations
• Users:
  – aviation/transportation
  – severe weather forecasting
  – general public forecasting

• Focus on 1-12 hour forecast range
• Accuracy of surface fields very important
Rapid Update Cycle Model Features
Vert Coord      Hybrid sigma-isentropic
Stable clouds, NCAR mixed-phase (cloud water,
precipitation rain water, snow, graupel, ice,
                ice particle number. concen.
Sub-grid        Grell-Devenyi ensemble scheme
precipitation   (144 members, mean to model)
Land-surface    RUC LSM - 6-level soil/veg model,
                2-layer snow model (Smirnova)

   Current operational RUC: 20-km
   Planned upgrade 2005:    13-km
        RUC Assimilation System
Updates         1-h cycle
Analysis        3DVAR on q/s surfaces (y/c/Zunb, q, lnQ)
Details         Balanced height (NMC method)
                Length-scales modified from OI
Sfc Obs/      Use surface obs through PBL
PBL Structure Lapse-rate checks

Noise           Adiabatic digital filter initialization

Clouds/         Cloud analysis (GOES cloudtop pres,
moisture        radar reflectivity, METAR clouds)

Cycling of cloud, hydrometeor, land-surface fields
     RUC Hourly Assimilation Cycle


  1-hr            1-hr         1-hr        1-hr        1-hr        1-hr
  fcst            fcst         fcst        fcst        fcst        fcst
Background    Analysis
  Fields        Fields

       3DVAR         3DVAR        3DVAR      3DVAR 3DVAR

        Obs              Obs          Obs     Obs         Obs

                                                                    Time
11           12           13          14          15          16    (UTC)
          RUC Hourly Assimilation Cycle


       3-hr            12-h        3-hr        3-hr        12-h        3-hr
       fcst            fcst        fcst        fcst        fcst        fcst
     Background    Analysis
       Fields        Fields

            3DVAR        3DVAR        3DVAR      3DVAR 3DVAR

             Obs          Obs             Obs     Obs         Obs

EC
                                                                        Time
     11           12          13          14          15          16    (UTC)
                                                 Cloud anx
      Observations used in RUC                   variables
Data Type                  ~Number       Freq.
--------------------------------------------------
Rawinsonde                    80         /12h




                                                     operational
NOAA profilers                30          / 1h
VAD winds                   110-130       / 1h




                                                       NCEP
Aircraft (V,temp)          1400-4500 / 1h
Surface/METAR              1500-1700 / 1h
Buoy/ship                   100-150      / 1h
GOES precip water          1500-3000 / 1h
GOES cloud winds           1000-2500 / 1h
GOES cloud-top pres ~10km res / 1h
SSM/I precip water         1000-4000 / 6h




                                                       experimental
--------------------------------------------------
GPS precip water            ~300         / 1h




                                                           FSL
Mesonet                     ~5000        / 1h
PBL – prof/RASS              ~20         / 1h
Radar refl / lightning         4 km res
--------------------------------------------------
Application of Digital Filter Initialization in RUC
• 45 min forward, 45 min backward – no physics
• Average over DFI period
RUC Analysis
3-d effect of
observations
dependent on
statistically
determined
forecast error
covariance
• vertical –
dependent on q
• horizontal –
smaller near
surface, larger
aloft,
                                                     RUC20
                                    6    9
                            1   3
                                               12    Wind forecast
                                                     Accuracy
        Analysis
        ~ ‘truth’
                                                     -Sept-Dec
                                                     2002




        6           8     10        12       (kts)

 Verification against rawinsonde data over RUC domain
 RMS vector difference (forecast vs. obs)

RUC is able to use recent obs to improve forecast skill
down to 1-h projection for winds
Results from fall 2002 – better moisture results in RUC13
Potential for more improvement from TAMDAR – V, T, RH
Use of surface obs information throughout
   boundary layer in the RUC analysis
Problem
• Information from surface
  observation not used through
  depth of PBL by RUC analysis
• Surface observation not
  retained in model forecast
                   Original
  Dewpoint
                   analysis

                Temperature



        *
  Surface
  Observation
Use of surface obs information throughout
   boundary layer in the RUC analysis
Problem                          Solution
• Information from surface       • Use METAR observation
  observation not used through   throughout PBL depth
  depth of PBL by RUC analysis   (from background field)
• Surface observation not        • Better model retention
  retained in model forecast     of surface observations
                   Original                        Analysis
  Dewpoint
                   analysis                        with use
                                                    of PBL
                                                    depth
                Temperature



        *
  Surface
  Observation
CAPE impact from two RUC enhancements
                       0000 UTC
                       21 Apr 2004




                  3h fcst                 3h fcst WITH
               OPERATIONAL               enhancements



RUC enhancements:
1. Use of METAR obs through
boundary-layer depth (Sept 04)

2. Assimilation of GPS precipitable    NWS SPC     Severe
water observations (May 2005)         Norman, OK   reports
             RUC Cloud Analysis
Use GOES CTP, radar reflectivity, lightning,
METAR (clouds,wx,vis) to modify moisture fields
• Construct 3-d logical arrays (YES/NO/UNKOWN)
   for clouds and precipitation from all info
• Clear/build (change qc, qi, qv) with logical arrays
• Safeguards for pressure-level assignment problems
   (marine stratus, convective clouds)
• Use nationwide mosaic radar data to modify water
   vapor, hydrometeor fields
• Lightning data used as a proxy for radar reflectivity
• Feedback to cumulus parameterization scheme
GOES cloud top pressure          Radar/lightning data
100                            100

200                            200
                                                        dBZ
300                            300            Qi
                          RH
400
                 Qv            400

500                            500
                                         Qs
600                            600

700                            700

800      Qc                    800

900                            900    Qr
999                            999
PRES                           PRES

Cloudwater, water vapor and    Rainwater, snow, cloud ice and
relative humidity before ( )   reflectivity before ( ) and after
and after (----) GOES Cloud-   (----) GOES radar/lightning
top pressure adjustment        adjustment
NESDIS GOES                 3h 20km fcst
Verification                WITH GOES
cloud-top prs               cloud assim




1200 UTC
9 Dec 2001      Cloud-top
                            3h 40km fcst
                pressure
                  (mb)      NO GOES
                            cloud assim
 Sample 20-km RUC
 forecast impact from
 GOES cloud-top pres.
 assimilation
Assimilation of METAR cloud/wx/vis
Better analysis, prediction of ceiling and visibility

  - Nearest station up to 100 km distance
  - Maps info to 3-d cloud, precip. Y/N/U arrays
  - Change qc, qi, qv as follows:
  Build for BKN / OVC / Vertical Visibility
   - 40 mb thick layer (2+ model levels)
   - 150 mb thick for precip + GOES clouds
   - Can build multiple broken layers
  Clear
   - Up to cloud base (if needed)
   - to 12 kft for CLR report
                           analysis – with   Cloud water
Sample modification        METAR cloud/      mixing ratio
                           visibility obs
of cloud water (qc)
from METAR
cloud/weather/
Visibility obs
             1700 UTC
             27 Jan 2004

 RH, q           Background – 1h fcst        Cloud water
                                             mixing ratio
       Sample ceiling
       analysis impact

                                                          Analysis
                                                           WITH
                                                          cld/wx/
                                                           vis obs
                                      Ceiling from RUC hydrometeors




                  Observations
1800 UTC
17 Nov 2003   Aviation Flight Rules
LIFR   IFR       MVFR     VFR   CLR                       Analysis
                                                             NO
                                                          cld/wx/
 cloud ceiling height (meters)                             vis obs
       Sample ceiling
       forecast impact

                                                            3h fcst
                                                            WITH
                                                           cld/wx/
                                                            vis obs
                                      Ceiling from RUC hydrometeors




                  Observations
2100 UTC
17 Nov 2003   Aviation Flight Rules
LIFR   IFR       MVFR     VFR   CLR                         3h fcst
                                                              NO
                                                           cld/wx/
 cloud ceiling height (meters)                              vis obs
Planned upgrades to RUC model
2005  13-km operational at NCEP
Assimilation of new observations
 - METAR cloud/vis/current weather
 - Mesonet
 - GPS precipitable water
 - Boundary layer profilers, RASS temperatures
 - Radar data (when available at NCEP)
Model improvements – new versions of:
 - Mixed-phase cloud microphysics (NCAR-FSL)
 - Grell-Devenyi convective parameterization

2007 Planned operational implementation
         of WRF-based rapid-refresh
3-d RUC        20km x 50 vertical levels
weather data   x 14 variables
updated hourly                               Turbulence




Convection -                                 Ceiling/visibility
2-12h forecast     Terminal / surface

                         Better weather       Icing
                 Winds   products require
                         improved high-
                         frequency
                         high-resolution
                         models
                         with high-refresh
                         data to feed them
Wind forecast ‘errors’
 - defined as rawinsonde
vs. forecast difference         Anx Fit
                                - ‘truth’


  Cntl = using all obs
  Exp = deny profiler obs




   Difference in errors
   between Cntl and Exp
   experiments w/ RUC
   - 4-17 Feb 2001

   Positive difference means
CNTL experiment with profiler
data had lower error than the
EXP-P no-profiler experiment
Wind forecast impact – US National domain
            3h
                                           6h

                                                6h


     3h


              Impact generally greatest for shorter forecast
             durations.
     12h      Decreases with projection except raobs
    12 h      Raob impact largest at 12h – raob frequency
             is 12h.
             Aircraft - largest overall impact at 3h, profiler
             next (much smaller)
             Modest VAD and METAR impact aloft;
             (METARs improve low-level height field, which
             helps zp mapping needed for VADs and
             profilers)
Real-time TAMDAR impact experiment design

• Parallel 20km RUC 1-h cycles
   • Dev cycle – all obs data but no TAMDAR
   • Dev2 cycle – dev + TAMDAR data
   • Lateral boundary conditions – same for Dev and Dev2

• Control design
   • Initialize Dev and Dev2 runs at exact same time
   • Reset dev and dev-2 background field at 1000z every 48
   h (even Julian dates)
       • Ensure against any computer logistics differences
• Evolution of dev vs. dev2 is different
   • Example – buddy check QC in each cycle may
   occasionally differ for non-TAMDAR data
   • Slight difference in gravity waves
       • Can propagate difference throughout domain
       • Shows up in sfc temps, convection, esp. 925, 850 mb
             0900z --------- 1200z


Sunday 10 April 2005

Reset of dev-dev2 difference at 1000z
• by copying Dev RUC 1-h forecast from 0900z as
background for Dev2 analysis at 1000z
• Reset is effective (although
Dev-Dev2 difference – 12h fcst
Init 1200z 10 April 2005 – 500 mb
Dev-Dev2 difference – 12h fcst
Init 1800z 10 April 2005 – 700 mb
Real-time TAMDAR impact experiment design

• Parallel 20km RUC 1-h cycles
   • Dev cycle – all obs data but no TAMDAR
   • Dev2 cycle – dev + TAMDAR data
   • Lateral boundary conditions – same for Dev and Dev2

• Control design
   • Initialize Dev and Dev2 runs at exact same time
   • Reset dev and dev-2 background field at 1000z every 48
   h (even Julian dates)
       • Ensure against any computer logistics differences
• Evolution of dev vs. dev2 is different
   • Example – buddy check QC in each cycle may
   occasionally differ for non-TAMDAR data
   • Slight difference in gravity waves
       • Can propagate difference throughout domain
       • Shows up in sfc temps, convection, esp. 925, 850 mb
Part 2 – Statistical results
Verification regions for FSL-RUC TAMDAR impact
Large region (eastern half of US) -- 38 RAOB sites
  Small region (Great Lakes) includes 14 RAOBs
Wind forecast ‘errors’
 - defined as rawinsonde
vs. forecast difference         Anx Fit
                                - ‘truth’


  Cntl = using all obs
  Exp = deny profiler obs




   Difference in errors
   between Cntl and Exp
   experiments w/ RUC
   - 4-17 Feb 2001

   Positive difference means
CNTL experiment with profiler
data had lower error than the
EXP-P no-profiler experiment
Temperature shows notable improvement for
850 mb, 3-h forecast in large (E.US) region
Even clearer improvement in the small (Gt Lakes) region
Temperature bias: small improvement for
         850 mb, 3-h forecast
Much improved temperature bias in small region
Temperature: some improvement for
      700 mb, 3-h forecast
Winds: not much difference
Relative Humidity: not much difference
  Results – wind – Great Lakes region only
  1 March – 12 April 2005

 Only 00z times
 --------------
 V          m/s

average diff by level

pres    0h-an     12h    3h      6h      9h                              1h
850     0.04     0.02   -0.07   -0.08    0.02    0.04    0.07   -0.01    0.09
700    -0.01     0.01    0.08    0.03   -0.05   -0.04   -0.02    0.03    0.06
500    -0.07     0.00    0.04   -0.04   -0.08   -0.04   -0.06    0.04   -0.08
400    -0.03     0.07    0.05   -0.06   -0.03   -0.02    0.03   -0.06   -0.04
300     0.00     0.06    0.04    0.09   -0.01    0.00    0.05   -0.02    0.00
250     0.00    -0.07    0.04    0.02   -0.05    0.03    0.02    0.00    0.05
200     0.01     0.07   -0.01   -0.04   -0.07    0.03    0.02   -0.01    0.04
150     0.02     0.01    0.07   -0.01    0.01    0.05   -0.01   -0.02    0.04
         Results – temperature – Gt Lakes region only
         1 March – 12 April 2005
 Only 00z times
 --------------
 T          deg C

average diff by level

pres    0h-anx 12h      3h      6h      9h       1h
850     0.13 -0.02     0.23    0.11   -0.02    0.36
700     0.05  0.00     0.06    0.04    0.01    0.03
500     0.01 -0.01     0.04    0.01   -0.01    0.05
400    -0.01 0.00     -0.02    0.00    0.00    0.01
300    -0.02   0.00   -0.03   -0.02   -0.01   -0.01
250    -0.05 -0.01    -0.03   -0.02    0.00   -0.01
200    -0.03   0.01   -0.02   -0.04   -0.01   -0.03
150     0.03  0.03    -0.01   -0.02    0.04    0.01
FSL-RUC TAMDAR impact experiment results
    (as of 12 April 2005)
• Impact experiments must be conducted such as to
show value added to other existing observations
    • RUC well-suited for this
• Real-time parallel cycles at FSL (Dev/Dev2) have
provided well-controlled experiments and results
    • Accelerated evaluation process
• Results are very preliminary and during TAMDAR
shakedown phase
    • Temperature impact strongest
        • ~20% reduction of 3h forecast error
    • RH impact less but positive
    • No impact for wind
    • Diurnal variations – more 3h impact at 00z than 12z
    • Results will improve with:
        • Improved TAMDAR data
        • Future use of reject lists (updated weekly?)

				
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