# Presentation: 675982

## Model Evaluation Tools(MET): An Overview

## Slide 2

## Slide 3

## MET Verification Techniques 

- Standard verification methods
- gridded model data to point-based observations
- gridded model data to gridded observations
- Object-based verification method
- comparing gridded model data to gridded observations

## Slide 5

## Working Example:6-h precip forecast valid 00z 2 June 08

**Forecast**

**Observations**

## Stage IV Hourly Precip Files

- ST4.2008060119.01h
- ST4.2008060120.01h
- ST4.2008060121.01h
- ST4.2008060122.01h
- ST4.2008060123.01h
- ST4.2008060200.01h

##  4-km Stage IV grid Specification

- 1121 x 881 polar stereographic grid.
- LL point: 23.117N 119.023W.
- UL point: 53.509N 134.039W.
- LR point: 19.805N 80.750W.
- UR point: 45.619N 59.959W.
- True longitude: 105W.
- The resolution is 4.7625km at 60N.
- The pole point is (I,J) = (400.5,1600.5)
- This and numerous other standard grids defined at:
- http://www.nco.ncep.noaa.gov/pmb/docs/on388/tableb.html

## Slide 9

## PCP-Combine command options

- pcp_combine  init_time
-                 in_accum
-                 valid_time
-                 out_accum
-                 out_file
-                 [-pcpdir path]
-                 [-pcprx reg_exp]

## PCP-combine command options

- init_time:
- Initialization time of the input Grib files in YYYYMMDD_HHMMSS format (required).
- in_accum:
- Accumulation interval of the input Grib files in HH format (required).
- valid_time:
- Desired valid time in YYYYMMDD_HHMMSS format (required).
- out_accum:
- Desired accumulation interval for the output NetCDF file in HH format (required).
- out_file:
- Name of the output NetCDF file to be written consisting of the sum of the accumulation intervals (required).

## PCP_combine example: Summing individual Stage IV hourly precip

- pcp_combine -sum 00000000_000000 01 20080602_000000 6 obs_6hr.nc -pcpdir .
- Note: Set init_time to 00000000_000000 when summing observation files
- Above command yields 6-hour OBS precip valid at 00z 2 June 2008 in netcdf format
- Filename “obs_6hr.nc”

## Regrid forecasts with “copygb”

- STIV Obs Grid – 1121x881,polar stereo,Dx,Dy 4763
- WRF Data Grid
- 308 x 310; Lambert Proj with Dx,Dy = 4000
- Extract precip grid from WRF output GRIB file
- Needs to be projected onto OBS grid (i.e. Stage IV)
- wgrib –V filename: provides necessary details on each grid

## Regrid forecasts with “copygb”

- Output of wgrib –V on Stage IV file yields:polar stereo: Lat1 23.117000 Long1 -119.023000 Orient -105.000000, north pole (1121 x 881)  Dx 4763 Dy 4763 scan 64 mode 8
- set grid="255 5 1121 881 23117 -119023 8 -105000 4763 4763 0 64"

## WRF Forecast GRIB files: 03z 1 June initialization time

- copygb -xg "$grid" -i1 -X WRFPRS15.tm00.d01.grb WRFPRS15.tm00.d01.grb.new
- copygb -xg "$grid" -i1 -X WRFPRS21.tm00.d01.grb WRFPRS21.tm00.d01.grb.new

## PCP-Combine for WRF files:Subtract 15-h from 21-h precip

- pcp_combine -subtract WRFPRS21.tm00.d01.grb.new 21 WRFPRS15.tm00.d01.grb.new 15 WRFPRS_6hr.nc

## Slide 17

## Slide 18

## MODE command

- mode fcst_file obs_file Config_file [options]
- Configuration file: WrfModeConfig
- mode WRFPRS_6hr.nc obs_6hr.nc WrfModeConfig

## MODE output

- 3 output formats– ASCII,NetCDF,PS
- mode_APCP_06_SFC_vs_APCP_06_SFC_240000L_20080602_030000V_060000A_cts.txt
- mode_APCP_06_SFC_vs_APCP_06_SFC_240000L_20080602_030000V_060000A_obj.nc
- mode_APCP_06_SFC_vs_APCP_06_SFC_240000L_20080602_030000V_060000A_obj.txt
- mode_APCP_06_SFC_vs_APCP_06_SFC_240000L_20080602_030000V_060000A.ps

## No Mask 		  Masking Obs

## 0.1 mm thresh 		  5.0 mm thresh

## Centroid radius variations800/(delta-x)  		  200/(delta-x)