NTDA-detected turbulence severity (eddy dissipation rate) is depicted. The data shown are from KINX, the NEXRAD radar near Tulsa, OK, on April 29, 2006. The range ring labels are in nautical miles.
The top frame shows radar reflectivity in dBZ. The bottom frame shows an example of winter weather hydrometeor classification using dual-polarimetric variables. Both frames are RHI (vertical) scans. Along the top of the cloud supercooled liquid drops, which can be an aviation hazard, are visible.
Priority 2: Developing New Instrumentation
Radar Development and Enhancement
Background
NCAR's Research Applications Laboratory (RAL) is working under the sponsorship of the FAA's Aviation Weather Research Program to develop radar products that use current and future capabilities of weather radars to detect and predict hazards specific to the aviation community. Two very different tasks are involved: deployment of new radar algorithms in a real-time environment, and research and development of radar products that will utilize future capabilities of weather radars.
Progress
The NEXRAD Turbulence Detection Algorithm (NTDA), developed by the FAA's Turbulence Product Development Team, has been implemented and tested in the Open Radar Products Generator (ORPG)?see Figure 1. By directly measuring the in-cloud turbulence intensity, the NTDA will give airline dispatchers, air traffic managers, and pilots an important new source of information for tactical turbulence avoidance. The performance of the prototype NTDA has been compared with research aircraft data and automated in situ turbulence reports from commercial aircraft, and it has been shown to have good skill. RAL is currently seeking approval for its deployment on the nation's NEXRAD radars.
Work also focused on determining the statistical properties of polarimetric radar measurements in known icing and nonicing conditions and on refining a wintertime Hydrometeor Classification Algorithm (HCA) for designating icing conditions. The winter HCA has demonstrated potential for making designations of freezing rain, discriminating between rain and snow in the terminal area, and specifying in-cloud icing conditions when the precipitation is dominated by supercooled liquid. The algorithm can also be used to identify storm regions where icing is unlikely.
Plans
NTDA will be delivered to the NEXRAD Radar Operation Center for integration into the ORPG system that is to be deployed in the spring of 2008. NCAR will also continue to work closely with the In Flight Icing product development team to determine how four dual-polarimetric radar fields can improve their products. NEXRAD radars are slated to have dual-polarimetric capabilities by 2012. RAL researchers are working to develop capabilities on these new radars for designating icing conditions both in the terminal area (freezing drizzle and rain) and in clouds, and for quantifying winter precipitation in support of airport deicing operations.
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