87th AMS Annual Meeting

Monday, 15 January 2007
Winter Test of All-Weather Precipitation Accumulation Gauge for ASOS 2005-2006
Exhibit Hall C (Henry B. Gonzalez Convention Center)
Christopher M. Greeney, SAIC, Sterling, VA; and J. V. Fiore Jr., J. M. Dover, and M. L. Salyards
Poster PDF (1.6 MB)
The heated tipping bucket is the standard liquid precipitation accumulation gauge used with the Automated Surface Observing System (ASOS). The sensor measures liquid accumulation, but is not specifically designed to accurately measure freezing or frozen precipitation. The accurate measurement of liquid equivalent accumulations in all types of liquid, solid, and mixed precipitation is an important part of weather observations.

The National Weather Service awarded a contract for design and development of an All Weather Precipitation Accumulation Gauge (AWPAG) on September 25, 2001, to C.C. Lynch and Associates (CCLA) of Pass Christian, Mississippi, in partnership with Ott Hydrometry of Kempten, Germany. Development testing from January 2002 to October 2003 demonstrated significant improvements in gauge catch, accuracy, and increased capacity. Full production AWPAGs were delivered in October 2003 and included hardware temperature compensation and revised internal sensor algorithm logic to improve gauge sensitivity.

Testing during the 2005-2006 winter season at Johnstown, Pennsylvania, applied various wind shield configurations to improve catch efficiency in wind-driven, light snow. The 2005-2006 test results showed that the best wind shield configuration was the addition of an outer 8-foot diameter Alter shield. In addition to an AWPAG comparison to the designated reference, the NWS standard 8-inch non-recording gauge with a 4-foot diameter Alter wind shield, AWPAG performance was also compared to a standard and small-scale Double Fence Intercomparison Reference (DFIR) wind shield both configured with a production AWPAG.

Statistical results from winter testing over the 2005-2006 season will be presented in the paper and at the conference.

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