Domain Configuration

    • CONUS domain with roughly 13-km grid spacing (selected such        that it fits within the RUC13 domain)
Click thumbnail for larger image.
Figure above shows the boundaries of the computational domain used for the ARW (dashed line), the NMM (dotted line) and the post-processed domain (solid line).

    • Grid dimensions:
       • NMM: 280 x 435 gridpoints, for a total of 121,800 horizontal        gridpoints
       • ARW: 400 x 304 gridpoints, for a total of 121,600 horizontal        gridpoints
       • Post-processed: 451 x 337 gridpoints, for a total of 151,987        horizontal gridpoints

    • 58 vertical levels - (Note: An exact match in vertical levels is not        possible because the ARW uses a sigma-pressure vertical        coordinate, while the NMM uses a hybrid system, with sigma-        pressure levels below 300 hPa and isobaric levels aloft)

    • Projections:
       • NMM: Rotated Latitude-Longitude projection
       • ARW: Lambert-Conformal map projection

Sample Namelists

     ARW configuration:
        namelist.wps
        namelist.input

     NMM configuration:
         namelist.wps
         namelist.input

Physics Suite

Microphysics:	Ferrier
Radiation (LW/SW):	GFDL
Surface Layer:	Janic
Land Surface:	Noah
PBL:	Mellor-Yamada-Janjic
Convection:	Betts-Miller-Janjic

Other run-time settings

    • Timestep:
       • ARW: Long timestep = 72 s; Acoustic timestep = 18 s
       • NMM: Long timestep = 30 s

    • Calls to the boundary layer, microphysics and cumulus        parameterization were made every time step for the ARW        (every 72 s) and every other time step for the NMM (every 60 s)

    • Calls to radiation were made every 30 minutes

    • Sample namelist.input for ARW and NMM

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): North American Mesoscale Model (NAM212)
       (Note: For the retrospective period used, the forecast
       component of the NAM was the Eta model.)

    • Sea Surface Temperature (SST) Initialization: NCEPs daily,        real-time SST product

Cases Run

The ARW and NMM dynamic cores were used to forecast 120 cases divided into the four seasons. The runs were initialized every 36 h, therefore, alternating 00 and 12 hr cycles, and run out to 60 hours.

Summer:	09 July - 24 August 2005
Fall:	10 October - 23 November 2005
Winter:	10 January - 22 February 2006
Spring:	10 April - 23 May 2006

The table below lists the forecast cases that were not verified due to the reasons described in the table.

Missing Verification:

Forecast cycle	Affected Case	Missing Data	Reason
Winter	2006011300	Incomplete 24-hr and 3-hr QPF verification	Missing RFC and ST2 analysis
	2006011412	Incomplete 24-hr and 3-hr QPF verification	Missing RFC and ST2 analysis
	2006011712	Incomplete sfc/ua verification	Missing RUC Prepbufr
	2006011900	Incomplete sfc/ua verification	Missing RUC Prepbufr
	2006021312	Incomplete 3-hr QPF verification	Corrupt ST2 analysis
	2006021500	Incomplete 3-hr QPF verification	Corrupt ST2 analysis
	2006021612	Incomplete sfc/ua verification	Missing RUC Prepbufr
	2006021800	Incomplete sfc/ua verification	Missing RUC Prepbufr
Fall	2005101212	Incomplete 3-hr QPF verification	Corrupt ST2 analysis
	2005103012	Incomplete sfc/ua verification	Missing RUC Prepbufr
	2005110100	Incomplete sfc/ua verification	Missing RUC Prepbufr
	2005110812	Incomplete sfc/ua verification	Missing RUC Prepbufr
	2005111000	Incomplete sfc/ua verification	Missing RUC Prepbufr
Summer	2005070912 (NMM only)	Incomplete 3-hr QPF verification (at 60-hr)	Unknown
	2005072812 (NMM only)	Incomplete 3-hr QPF verification (at 60-hr)	Unknown
Spring	2006042200	Incomplete 24-hr QPF and sfc/ua verification	Missing RFC analysis and RUC Prepbufr
	2006042312	Incomplete 24-hr QPF and sfc/ua verification	Missing RFC analysis and RUC Prepbufr
	2006050100	Incomplete 3-hr QPF verification	Missing ST2 analysis
	2006051300	Incomplete sfc/ua verification	Missing RUC Prepbufr
	2006051412	Incomplete sfc/ua verification	Missing RUC Prepbufr
	2006052312	Incomplete sfc/ua verification	Missing RUC Prepbufr

Verification

The NCEP Verification System is comprised of:
    • Surface and Upper Air Verification System (grid-to-point        comparison)
    • Quantitative Precipitation Forecast (QPF) Verification
       System (grid-to-grid comparison)

From these, model verification partial sums (aggregated by geographical region using the mean) were generated and objective model verification statistics were then computed using the statistical programming language, R. Confidence intervals (CIs), at the 99% level, were applied to each of the variables using the appropriate statistical method.

Objective verification statistics generated included:
    • Bias-corrected Root Mean Square Error (BCRMSE) and Mean
       Error (Bias) for:
        • Surface Temperature (2 m), Relative Humidity (2 m) and            Winds (10 m)
        • Upper Air Temperature, Relative Humidity and Winds

    • Equitable Threat Score (ETS) and Frequency Bias (FBias) for:
        • 3-hr and 24-hr Precipiation Accumulation intervals

Verification statistics were only computed for cases that ran to completion for both configurations. This allowed for a pair-wise difference technique, which takes advantage of the fact that both configurations faced the same forecast challenge for all cases, to be employed in the determination of statistically significant differences between the two configurations. The CIs on the pair-wise differences between statistics for the two configurations objectively determines whether the differences are statistically significant (SS).

Verification results were computed for select spatial aggregations, including the entire CONUS (G164), CONUS-West (G165), and CONUS-East (G166) domains (shown here).