NOUS41 KWBC 021229
PNSWSH
Technical
Implementation Notice 11-54
National Weather
Service Headquarters Washington DC
830 AM EDT Fri
Nov 2 2011
To: Subscribers
-Family of Services
-NOAA Weather Wire Service
-NOAAPORT
-Emergency Managers Weather
Information Network
Other NWS Partners, Users and
Employees
From: Jay Lawrimore
Chief, Climate Analysis Branch
National Climatic Data Center
SUBJECT: Rounding Algorithm Revision for the Hourly02
and
Daily01 Products
Effective December 1, 2012
Effective
Tuesday, December 1, 2012, at approximately 1500
Coordinated
Universal Time (UTC), The National Climatic Data
Center will
change the rounding algorithm used for the hourly02
(CRNH02)
and daily01 (CRND01) products.
These revisions will
affect some of the reported negative values for
stations of the
U.S. Climate
Reference Network (USCRN) and the U.S. Historical
Climatology
Network-Modernization (USHCN-M).
Prior to
September 2012, USCRN used symmetric half-up (away from
zero) rounding for processing and publishing
data; however, to
align with the World Meteorological Organization’s
requirement to
use asymmetric half-up rounding in important meteorological
summaries and the recommendations of the National Data
Stewardship Team
(NDST), USCRN has switched to using asymmetric
half-up rounding for internal data processing. To
finalize the
transition to asymmetric half-up rounding, USCRN’s data
product
software will also switch to using the new rounding
algorithm.
Users of the
hourly02 or daily01 products should expect to see
some of the previously reported negative values
change by 0.1 in
the positive direction (towards zero). This
change of rounding
algorithm will not affect the file formats of the two
products.
Prior versions of
both products will remain available through the
snapshot zip files that are produced weekly.
More details on
the rounding practices recommended by the
National Data
Stewardship Team can be found at
http://www1.ncdc.noaa.gov/pub/data/uscrn/documentation/program/NDST_Rounding_Advice.pdf
If you have
questions or feedback, please contact:
Scott Embler
National Climatic Data Center
151 Patton Ave
Asheville, NC
28803
828-350-2027
NWS Technical
Implementation Notices are online at:
http://www.weather.gov/os/notif.htm
$$