Weather supportfor terminal area icing weather information

The Federal Aviation Administration (FAA) recently published a Notice of Proposed Rulemaking on certification of aircraft for operation in supercooled large drop (SLD) icing conditions with a final rule expected in 2014. One likely consequence of the rule is new limitations on takeoff andlanding in freezing drizzle and/or freezing rain conditions for new aircraft that are not fully certified to operate in these conditions as described in the new regulation. This will impact terminal area operations for airports in icing weather conditions and will require that local, highly-resolved, real-time icing condition information be made available for aircraft take-off and landing guidance for all decision-makers: air traffic control, weather dispatchers, ground de-icing facilities, airline operators, and flight crews. To address these issues, the FAA has begun funding research under a new project known as the Terminal Area Icing Weather Information for NextGen (TAIWIN), the goal of which is to improve measurements of icing conditions within the airport terminal area both at the ground and aloft. The initial focus of this project has been on three different areas; feasibility of automated detection of freezing drizzle at the surface using the Automated Surface Observing System (ASOS), development of new data quality control procedures for liquid water equivalent (LWE) gauge measurements, and assessment of snowfall variability across the terminal area and. Initial results from all three areas are presented.