[nws-changes] 20071206: North American Mesoscale model: ADMIN NOTICE NOUS41 KWBC]

[Linda Miller]

-------- Original Message --------

661 
NOUS41 KWBC 061512
PNSWSH

TECHNICAL IMPLEMENTATION NOTICE 07-96
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
1010 AM EST THU DEC 6 2007

TO:       FAMILY OF SERVICES /FOS/ SUBSCRIBERS...NOAA WEATHER     
          WIRE SERVICE /NWWS/SUBSCRIBERS...EMERGENCY MANAGERS 
          WEATHER INFORMATION NETWORK /EMWIN/ SUBSCRIBERS... 
          NOAAPORT SUBSCRIBERS...OTHER NATIONAL WEATHER SERVICE 
          /NWS/ PARTNERS AND USERS...NWS EMPLOYEES

FROM:     PAUL HIRSCHBERG
          SCIENCE PLANS BRANCH CHIEF
          OFFICE OF SCIENCE AND TECHNOLOGY /OST/ 

SUBJECT:  NORTH AMERICAN MESOSCALE MODEL CHANGES:     
          EFFECTIVE FEBRUARY 19 2008

EFFECTIVE TUESDAY 19 FEBRUARY 2008...BEGINNING WITH THE 1200 
COORDINATED UNIVERSAL TIME /UTC/ RUN...SEVERAL CHANGES WILL BE 
MADE TO:
- WEATHER RESEARCH FORECAST NON-HYDROSTATIC MESOSCALE MODEL
  /WRF-NMM/ RUNNING IN THE NORTH AMERICAN MESOSCALE MODEL /NAM/
- NAM DATA ASSIMILATION SYSTEM /NDAS/ 
- DOWNSCALED GLOBAL FORECAST SYSTEM /GFS/ WITH ETA EXTENSION
  /DGEX/. 
- GRIDPOINT STATISTICAL INTERPOLATION /GSI/ ANALYSIS WHICH
  PROVIDES INITIAL CONDITIONS TO THE NDAS AND NAM FORECASTS.
  
THESE CHANGES ARE BEING MADE TO IMPROVE MODEL PERFORMANCE.
THE MODEL CHANGES INCLUDE:

1. THE COMPUTATIONAL DOMAIN OF THE NAM WILL BE INCREASED BY  
18 PERCENT. TO SEE A COMPARISON OF THE CURRENT OPERATIONAL AND 
EXPANDED NAM DOMAINS, GO TO /USE LOWERCASE LETTERS/:  
          
HTTP://WWW.EMC.NCEP.NOAA.GOV/MMB/MMBPLL/PARALOG/OVERLAY_ETA12_
EXPANDED.JPG

BECAUSE THE NAM MODEL DOMAIN IS BEING ENLARGED BY 18 PERCENT 
...THE BIT DEFINITION SECTION /BIT-MAP/ OF NAM OUTPUT GRIDS... 
WHICH OVERLAP THE NAM INTEGRATION DOMAIN... WILL BE REDUCED OR 
ELIMINATED. THIS CHANGE IS OCCURRING BECAUSE VALID MODEL DATA 
WILL BE AVAILABLE OVER A LARGER AREA. WHEN NCEP CENTRAL 
OPERATIONS BEGINS RUNNING THE PARALLEL NAM.... SAMPLE NAM GRIB 
OUTPUT WITH THE MODIFIED BIT-MAP REPRESENTATION WILL BE AVAILABLE 
ON THE NCEP FTP SERVER. THIS NOTICE WILL BE UPDATED AT THAT TIME 
TO REFLECT THE LOCATION OF THE DATA.

2. TWO MINOR CHANGES WILL BE MADE TO THE WRF-NMM MODEL RADIATION 
PARAMETERIZATION. 

3. CHANGES WILL BE MADE TO THE WRF-NMM OROGRAPHY AND LAND-SEA 
MASK INCLUDING A MORE REALISTIC DEPICTION OF THE GREAT SALT LAKE 
AND THE CHANNEL ISLANDS OFF THE CALIFORNIA COAST...SMOOTHER NAM 
SURFACE HEIGHT AND REMOVAL OF SPURIOUS ELEVATED WATER POINTS. 

4. DURING THE NDAS FORECAST...THE 12-36 HOUR FORECAST 
PRECIPITATION FROM THE 00Z OPS NAM RUN WILL BE USED TO FILL IN 
FOR THE CONUS-BASED STAGE II/IV ANALYSIS AS A DRIVER FOR NDAS 
SOIL MOISTURE OUTSIDE OF THE CONUS /OCONUS/.

5. THE NEW /UNIFIED/ LAND-SURFACE PHYSICS MODULE WILL BE USED.

6. A MODIFIED HORIZONTAL ADVECTION ALGORITHM FOR CLOUD 
WATER...SPECIFIC HUMIDITY...AND TURBULENT KINETIC ENERGY WILL BE 
USED.

7. THE WRF-NMM MODEL DYNAMICS WILL BE MODIFIED TO INCLUDE THE 
EFFECTS OF GRAVITY-WAVE DRAG AND MOUNTAIN BLOCKING.

THE ANALYSIS CHANGES INCLUDE:

1. ASSIMILATION OF NEW OBSERVATION TYPES...INCLUDING AIRS AND 
GOES 1X1 RADIANCE DATA...ADDITIONAL SATELLITE WIND DATA...AND 
SURFACE MESONET WIND DATA.

2. REVISED BACKGROUND ERROR COVARIANCES TO IMPROVE THE ANALYSIS 
FIT TO THE OBSERVATIONS.

ALL WRF-NMM MODEL CHANGES WILL BE SIMULTANEOUSLY IMPLEMENTED INTO 
THE DGEX.

IN ADDITION TO THE CHANGES TO THE NAM OUTPUT GRIDS BIT-DEFINITION 
SECTION...OTHER OUTPUT CHANGES INCLUDE:

1. ADDING FIVE NEW FIELDS TO THE NAM 32KM OUTPUT GRID #221 
/AWIP32/ AND 12KM OUTPUT GRID #218 /AWIP12/: THE FIRST FOUR 
FIELDS ARE TOTAL COLUMN-INTEGRATED HEATING RATES: 
CONVECTIVE...GRID-SCALE... LONGWAVE...AND SHORTWAVE. THE FIFTH 
ADDED FIELD WILL BE TOTAL COLUMN-INTEGRATED MOISTURE DIVERGENCE.

2. THE NAM HOURLY PROFILE DATA IN BUFR FORMAT HAS GAINED 17 NEW 
STATIONS.

THE COMBINED IMPACT OF THESE CHANGES HAS LED TO:

1. IMPROVED NAM FORECAST PERFORMANCE BASED ON QUANTITATIVE SKILL 
SCORES FOR HEIGHTS AND TEMPERATURE /RMS ERROR AND BIAS/ OVER BOTH 
THE CONUS AND ALASKA...SPECIFICALLY IN REDUCING LOWER 
TROPOSPHERIC/850/700 MB/ COLD BIAS AND IMPROVED 10-M WIND 
FORECASTS.

2. IMPROVED NDAS/NAM SOIL MOISTURE STATES IN REGIONS OUTSIDE OF 
THE CONUS.

MORE DETAILS ABOUT THESE CHANGES CAN BE SEEN AT /USE LOWERCASE 
LETTERS/:

HTTP://WWWT.EMC.NCEP.NOAA.GOV/MMB/MMBPLL/PARALOG/PARALOG. 
NAMEXP.HTML

WHEN IT BECOMES AVAILABLE...A COPY OF THE BRIEFING PACKAGE FOR 
THE NCEP DIRECTOR CAN BE FOUND AT /USE LOWERCASE LETTERS/:

HTTP://WWW.EMC.NCEP.NOAA.GOV/MMB/NAMCHANGES_WINTER2008/ 
NAM_UPGRADES.2008.HTML

DATA DELIVERY TIMING WILL NOT BE IMPACTED BY THIS IMPLEMENTATION. 
THE NAM DELIVERY TIME WILL NOT CHANGE.

DATA VOLUMES ARE EXPECTED TO CHANGE FOR SOME NAM OUTPUT GRIDS DUE 
TO GRIB BIT-MAP CHANGES CAUSED BY THE 18% INCREASE IN DOMAIN 
SIZE...SPECIFICALLY:

1. OUTPUT FILES ON THE NAM NATIVE E-GRID WILL BE 18% BIGGER

2. OUTPUT GRIDS THAT NO LONGER HAVE A BITMAP FROM THE EXPANDED
   NAM WILL BE 8-10 PERCENT SMALLER

3. OUTPUT GRIDS WITH SMALLER BITMAPS FROM THE EXPANDED NAM WILL
   BE 1-8 PERCENT BIGGER

SIGNIFICANT DATA CONTENT CHANGES ARE EXPECTED AS MENTIONED 
EARLIER. THESE CONTENT CHANGES WILL IMPACT ALL DISSEMINATION 
ROUTES WHICH INCLUDE NOAAPORT...THE NWS PUBLIC FTP SERVER AND THE 
NCEP PUBLIC FTP SERVER. A CONSISTENT PARALLEL FEED OF DATA WILL 
BECOME AVAILABLE ON THE NCEP FTP SERVER ONCE THE MODEL IS RUNNING 
IN PARALLEL ON THE NCEP CENTRAL COMPUTING SYSTEM. NCEP WILL SEND 
ANOTHER NOTICE ALERTING USERS TO THE LOCATION OF THESE DATA SETS 
ONCE THEY BECOME AVAILABLE.

NCEP ENCOURAGES ALL USERS TO ENSURE THEIR DECODERS ARE FLEXIBLE 
AND ARE ABLE TO ADEQUATELY HANDLE CHANGES IN CONTENT ORDER... 
PARAMETER FIELDS CHANGING ORDER...CHANGES IN THE SCALING FACTOR 
COMPONENT WITHIN THE PDS OF THE GRIB FILES AND ALSO ANY VOLUME 
CHANGES WHICH MAY BE FORTHCOMING. THESE ELEMENTS MAY CHANGE WITH 
FUTURE NCEP MODEL IMPLEMENTATIONS. NCEP WILL MAKE EVERY ATTEMPT 
TO ALERT USERS TO THESE CHANGES BEFORE IMPLEMENTATION.

FOR QUESTIONS CONCERNING THESE CHANGES...PLEASE CONTACT: 

GEOFF DIMEGO
NCEP...MESOSCALE MODELING BRANCH
CAMP SPRINGS MARYLAND
PHONE: 301.763.8000 X7221
EMAIL: GEOFF.DIMEGO at NOAA.GOV
OR
ERIC ROGERS
NCEP...MESOSCALE MODELING BRANCH
CAMP SPRINGS MARYLAND
PHONE: 301.763.8000 X7227
EMAIL: ERIC.ROGERS at NOAA.GOV

THIS AND OTHER NWS TECHNICAL IMPLEMENTATION NOTICES ARE AVAILABLE 
ONLINE AT /USE LOWER CASE LETTERS/:

     HTTP://WWW.NWS.NOAA.GOV/OM/NOTIF.HTM

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