Codes Employed

The components of the end-to-end forecast system used include the most recent versions of the following system components:

    • WRF Preprocessing System (WPS)

    • WRF-ARW model

    • Unified Post Processor (UPP)

    • Model Evaluation Tools (MET) *Includes PB2NC bug fix

    • NCAR Command Language (NCL) for graphics generation

    • Statistical programming language, R, to compute confidence        intervals

Domain Configuration

    • Near-North American domain with 15-km grid spacing

Click thumbnail for larger image.

    • Coarse domain: 656 x 464 gridpoints, for a total of 304,384 horizontal gridpoints
    • 36 vertical levels (37 sigma entries); model top at 50 hPa

    • Lambert-Conformal map projection

Sample Namelists

    • namelist.wps

    • namelist.input (v3.4)

    • namelist.input (v3.4.1)

    • namelist.input (v3.5)

    • namelist.input (v3.5.1)

    • namelist.input (v3.6)

AFWA Reference Configuration

Microphysics:	WRF Single-Moment 5 Simple Ice Scheme
Radiation (LW/SW):	RRTM/Dudhia
Surface Layer:	Monin-Obukhov Similarity Theory
Land Surface:	Noah
PBL:	Yonsei University Scheme
Convection:	Kain-Fritsch Scheme

    • Sample namelist.input

Other run-time settings

    • Long timestep = 90 s; Acoustic step = 4
    • Calls to the boundary layer and microphysics parameterization        were made every time step
    • Calls to the cumulus parameterization were made every 5        minutes
    • Calls to radiation were made every 30 minutes

The end-to-end system for this test did not include a data assimilation component.

Initial and Boundary Conditions

    • Initial conditions (ICs) and Lateral Boundary Conditions
       (LBCs): 0.5 x 0.5 degree Global Forecast System (GFS) model

    • SST Initialization: Fleet Numerical Meteorology and        Oceanography Center (FNMOC) daily, real-time sea surface        temperature (SST) product

Preprocessing Component

The time-invariant component of the lower boundary conditions (topography, soil and vegetation type etc.), using United States Geological Survey (USGS) input data, was generated through the geogrid program of WPS.

Cases Run

• Forecast Dates: Summer:1 July 2011 - 30 September 2011
                              Winter: 1 January 2012 - 31 March 2012
• Initializations: Every 36 hours, including both 00 and 12 UTC

• Forecast Length: 48 hours; output files generated every 3 hours

00 UTC Initializations
July 2011: 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31
August 2011: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30
September 2011: 2, 5, 8, 11, 14, 17, 20, 23, 26, 29
January 2012: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30
February 2012: 2, 5, 8, 11, 14, 17, 20, 23, 26, 29
March 2012: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30

12 UTC Initializations
July 2011: 2, 5, 8, 11, 14, 17, 20, 23, 26, 29
August 2011: 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31
September 2011: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30
January 2012: 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31
February 2012: 3, 6, 9, 12, 15, 18, 21, 24, 27
March 2012: 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31

The tables below list the forecast initializations that failed to complete the end-to-end process due to the reasons described in the table. All incomplete forecasts were due to missing or bad input data sets, not model crashes.

Missing Forecasts:

Affected Case	Missing Data	Reason
2011071712	WRF Output	Missing SST Input Data
2011080112	WRF Output	Missing SST Input Data
2011082400	WRF Output	Missing SST Input Data
2012011012	WRF Output	Missing GFS input data
2012011612	WRF Output	Missing GFS input data
2012012212	WRF Output	Missing GFS input data

Missing Verification:

Affected Case	Missing Data	Reason
2011072500	Missing 3-h QPF verification for 18 21-h Missing 24-h QPF verification for 36-h	Missing ST2 analysis

Verification

The Model Evaluation Tools (MET) package, comprised of:

    • grid-to-point comparisons - utilized for surface and upper air        model data
    • grid-to-grid comparisons - utilized for QPF

was used to generate objective verification statistics, including:

    • Bias-corrected Root Mean Square Error (BCRMSE) and Mean
       Error (Bias) for:
        • Surface: Temperature (2 m), Dew Point Temperature (2 m)            and Winds (10 m)
        • Upper Air: Temperature, Dew Point Temperature and Winds

    • Gilbert Skill Score (GSS) and Frequency Bias (FBias) for:
        • 3-hr and 24-hr Precipiation Accumulation intervals

Each type of verification metric is accompanied by confidence intervals (CIs), at the 99% level, computed using a parametric method for the surface and upper air variables and a boostrapping method for precipitation.

Both configurations were run for the same cases allowing for a pair-wise difference methodology to be applied, as appropriate. The CIs on the pair-wise differences between statistics for the two configurations objectively determines whether the differences are statistically significant (SS).

To establish practical significance (PS) in order to examine SS pair-wise differences that are potentially more meaningful, the data was censored to only look at differences that were greater than the operational measurement uncertainty requirements as defined by the World Meteorological Organization (WMO). The following criteria were applied to determine PS pair-wise differences between the configurations and versions for select variables: i) temperature and dew point temperature differences greater than 0.1K and ii) wind speed differences greater than 0.5 ms^-1.

Area-averaged verification results were computed for the full and CONUS domains, East and West domains, and 14 sub-domains.