Tuesday, 24 January 2012: 4:00 PM
The Importance of Wind Shielding At the NOAA/FAA/NCAR Winter Precipitation Testbed
Room 239 (New Orleans Convention Center )
Although precipitation is an important fundamental meteorological variable, wintertime precipitation measurement is beset with significant errors. At the NOAA/FAA/NCAR winter precipitation testbed in Marshall, CO an intercomparison of methodologies used to measure winter precipitation is ongoing. As part of the research performed at the testbed, liquid equivalent snowfall measurements from weighing precipitation gauges within different windshields were compared. Measurements from the Geonor weighing precipitation gauge (T-200B) recorded simultaneously within 6 different types of windshield indicate that a new, Belfort double Alter shield shows significant improvement in catch efficiency over the traditional double Alter windshield due to a decrease in porosity from 50% to 30%. In most events the Belfort double Alter measurements compared well to double-fence intercomparison reference shield (DFIR) and small (2/3 size) DFIR (SDFIR) measurements. Using the (S)DFIR measurements as a standard, catch efficiencies from the traditional single and double Alter shields, the Belfort single Alter shield, and an unshielded gauge decreased significantly with wind speed.