-------- Original Message --------
971
NOUS41 KWBC 281358
PNSWSH
TECHNICAL IMPLEMENTATION NOTICE 02-30A
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
1000 AM EDT THU SEP 28 2006
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: MIKE CAMPBELL
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 FOLLOWING ASOS LOCATIONS HAVE OR WILL TRANSITION TO THE IFW
CONFIGURATION ON THE INDICATED DATES:
HTL HOUGHTON LAKE ASOS SEPTEMBER 29, 2006
IF YOU HAVE ANY QUESTIONS ABOUT THIS CHANGE...PLEASE CONTACT ONE OF
THE FOLLOWING INDIVIDUALS AT NWS HEADQUARTERS:
JAMES HEIL
SURFACE OBSERVATIONS FOCAL POINT
PHONE: 301-713-1792 X140
E-MAIL: JAMES.HEIL@xxxxxxxx
OR
RICHARD AHLBERG
ASOS PLANNED PRODUCT IMPROVEMENT PROGRAM MANAGER
PHONE: 301-713-1975 X160
E-MAIL: RICHARD.AHLBERG@xxxxxxxx.
THIS AND OTHER NWS TECHNICAL IMPLEMENTATION NOTICES ARE AVAILABLE
ON THE INTERNET AT /USE LOWER CASE/:
HTTP://WWW.NWS.NOAA.GOV/OM/NOTIF.HTM
END
$$
NNNN
--
Linda Miller - lmiller@xxxxxxxxxxxxxxxx
Community Services, Unidata
University Corporation for Atmospheric Research
P.O. Box 3000
Boulder, CO 80307-3000
303-497-8646 fax: 303-497-8690
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