NOUS41 KWBC 252021
PNSWSH

PUBLIC INFO. STATEMENT...TECHNICAL IMPLEMENTATION NOTICE 02-30
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
420 PM EDT FRI OCT 25 2002

TO:       FAMILY OF SERVICES /FOS/ SUBSCRIBERS...NOAA WEATHER
          WIRE SERVICE /NWWS/ SUBSCRIBERS...EMERGENCY MANAGERS
          WEATHER INFORMATION NETWORK /EMWIN/ SUBSCRIBERS...
          OTHER NATIONAL WEATHER SERVICE /NWS/ CUSTOMERS OF
          AVIATION DATA AND FORECASTS...NWS EMPLOYEES

FROM:     RAINER DOMBROWSKY
          CHIEF...OBSERVING SERVICES DIVISION

SUBJECT:  AUTOMATED SURFACE OBSERVING SYSTEM WIND SENSOR
          REPLACEMENT

THE FOLLOWING CHANGES HAVE NO DIRECT IMPACT ON NOAA WEATHER WIRE
SERVICE SUBSCRIBERS

THE AUTOMATED SURFACE OBSERVING SYSTEM /ASOS/ PRODUCT IMPROVEMENT
PROGRAM WILL SOON DEPLOY A REPLACEMENT WIND SENSOR.  THE NEW
SENSOR WILL REPORT WIND INFORMATION USING THE 3-SECOND WORLD
METEOROLOGICAL ORGANIZATION /WMO/ GUST STANDARD.

THE CURRENT ASOS WIND SENSOR /BELFORT 2000 / USES ROTATING CUPS
TO MEASURE WIND SPEED AND A VANE TO MEASURE WIND DIRECTION.  OVER
A 2-MINUTE PERIOD...ASOS USES TWENTY-FOUR 5-SECOND AVERAGES TO
DETERMINE THE 2-MINUTE AVERAGE WIND SPEED AND DIRECTION.  EVERY
MINUTE ASOS STORES THE HIGHEST 5-SECOND AVERAGE SPEED FOR THE
PAST MINUTE... ALONG WITH ITS DIRECTION... IN THE 12-HOUR ARCHIVE
FOR ADDITIONAL PROCESSING.  THIS HIGHEST SPEED VALUE IS USED TO
DETERMINE IF A GUST AND/OR A PEAK WIND REMARK WILL BE REPORTED.

THE NEW ASOS WIND SENSOR /VAISALA 425NWS / IS A SONIC ANEMOMETER. 
IT HAS NO MOVING PARTS AND WILL OPERATE BETTER IN WINTER WEATHER
CONDITIONS.  AS WITH THE BELFORT SENSOR...OVER A 2-MINUTE
PERIOD...ASOS USES TWENTY-FOUR 5-SECOND AVERAGES TO DETERMINE THE
2-MINUTE AVERAGE WIND SPEED AND DIRECTION.  BUT THE HIGHEST
3-SECOND RUNNING AVERAGE SPEED IS STORED FOR GUST AND PEAK WIND
PROCESSING.

WHILE THERE WILL BE LITTLE DIFFERENCE IN 2-MINUTE AVERAGE WIND
SPEED AND DIRECTION REPORTING...THE CHANGES IN GUST AND PEAK WIND
REPORTING MAY BE SIGNIFICANT.  WE CAN EXPECT TO SEE MORE GUSTS
AND PEAK WINDS REPORTED WITH THE NEW SENSOR.  THE MASS OF THE
MOVING PARTS IN EXISTING SENSORS LIMITS RESPONSIVENESS.  THE NEW
SENSOR WILL BE MORE RESPONSIVE TO SHORT TERM GUSTS.

THE LAST ACTIVITY PRIOR TO IMPLEMENTATION AT 313 NWS AND 570 FAA
SPONSORED SITES IS A 20 SITE OPERATIONAL ACCEPTANCE TEST /OAT/. 
THE OAT WILL BEGIN IN EARLY NOVEMBER OF 2002.  EIGHTEEN /18/ OF
THE 20 OAT SITES WILL BE CONFIGURED WITH DUAL SENSORS...BOTH THE
EXISTING AND NEW SENSOR.  THE EXISTING SENSOR WILL BE USED FOR
THE OFFICIAL OBSERVATION AT LOCATIONS WHERE DUAL SENSORS ARE
INSTALLED.   INITIALLY THE NEW SENSOR OUTPUT WILL BE ARCHIVED FOR
ANALYSIS.  WHEN THE ANALYSIS VALIDATES THE NEW SENSOR
PERFORMANCE...THE PROCESSING WILL BE CHANGED TO USE THE NEW
SENSOR FOR THE OFFICIAL OBSERVATION AND THE NEW SENSORS WILL BE
INSTALLED AT THE REMAINING 2 SINGLE SENSOR OAT SITES.  BELFORT
SENSOR DATA WILL CONTINUE TO BE ARCHIVED AT THE DUAL SENSOR
SITES.  THIS CHANGE IN THE USE OF SENSORS IS EXPECTED TO OCCUR IN
DECEMBER 2002.  FOLLOWING A SUCCESSFUL OAT...FULL SCALE
DEPLOYMENT OF THE NEW SENSOR WILL BEGIN IN MARCH OF 2003 AND
EXTEND THROUGH SEPTEMBER 2006.

                         OAT LOCATIONS

     SID  STATION NAME        CONFIGURATION       DEPLOYMENT DATE
     
     BRW  BARROW AK           DUAL                NOVEMBER 2002
     TKA  TALKEETNA, AK       DUAL                NOVEMBER 2002
     KTN  KETCHICAN AK        DUAL                NOVEMBER 2002
     SIT  SITKA AK            DUAL                NOVEMBER 2002
     CMX  HANCOCK MI          DUAL                NOVEMBER 2002
     GFK  GRAND FORKS ND      DUAL                NOVEMBER 2002
     TOP  TOPEKA KS           DUAL                NOVEMBER 2002
     BFF  SCOTTSBLUFF NE      DUAL                NOVEMBER 2002
     HUF  TERRA HAUTE  IN     DUAL                NOVEMBER 2002
     OSH  OSHKOSH WI          DUAL                NOVEMBER 2002
     ARR  CHICAGO/AURORA IL   DUAL                NOVEMBER 2002
     FTW  FORT WORTH TX       DUAL                NOVEMBER 2002
     NEW  NEW ORLEANS  LA     DUAL                NOVEMBER 2002
     LLJ  CHALLIS ID          DUAL                NOVEMBER 2002
     UAO  AURORA OR           DUAL                NOVEMBER 2002
     BLU  BLUE CANYON CA      DUAL                NOVEMBER 2002
     BTV  BURLINGTON VT       DUAL                NOVEMBER 2002
     CAR  CARIBOU ME          DUAL                NOVEMBER 2002
     ITO  HILO HI             SINGLE              DECEMBER 2002
     SFO  SAN FRANCISCO CA    SINGLE              DECEMBER 2002

IF YOU HAVE ANY QUESTIONS ABOUT THIS CHANGE...PLEASE CONTACT ONE
OF THE FOLLOWING INDIVIDUALS AT NWS HEADQUARTERS:

	TIMOTHY ROSS
	SURFACE OBSERVATIONS PROGRAM MANAGER
	PHONE:  301-713-1792 X114
	E-MAIL: TIM.ROSS@NOAA.GOV 

		OR 

	RICHARD AHLBERG 
	ASOS PLANNED PRODUCT IMPROVEMENT PROGRAM MANAGER
	PHONE:  301-713-1975  X160
	E-MAIL: RICHARD.AHLBERG@NOAA.GOV.

THIS AND OTHER NWS TECHNICAL IMPLEMENTATION NOTICES ARE AVAILABLE
ON THE INTERNET AT /USE LOWER CASE/:

     http://www.nws.noaa.gov/om/notif.htm

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