The aim of NSSL's work in support of WARP has recently changed to provide the National Air Traffic Controllers Association (NATCA) with guidance on the accuracy of composite reflectivity products. It has been decided that ORPG product 96 (0-70,000 ft composite reflectivity with AP mitigation) will replace product 36 (0-70,000 composite reflectivity without AP mitigation) in the Spring of 2003. NSSL will provide guidance on the accuracy of the AP mitigation scheme used in a variety of meteorological environments. The accuracy of the AP mitigation scheme will be tested in AP events such as nocturnal inversions, convective outflow regions, or events when AP is embedded within convection. But also, the AP mitigation scheme will be examined for cases where no AP is present to determine if it removes precipitation or reduces the magnitude of reflectivity within convective events.

Several test cases have been truthed to identify separate regions of precipitation and AP and will be used to determine AP mitigation accuracy in the composite reflectivity products. Test cases that have been truthed include:

• nocturnal AP
• AP co-existent with but not embedded within convection
• AP embedded within a mesoscale convective system
• sea clutter
• multicellular convection with no AP