Reflectivity At Lowest Altitude (RALA) - Reflectivity At Lowest Altitude (RALA) - Warning Decision Training Division (WDTD)
Reflectivity At Lowest Altitude (RALA)
Short DescriptionReflectivity at the lowest sampled vertical level that contains data.
Low-Resolution (5 km) RALA
Raw RALA, un-quality-controlled RALA
NWS: WFO, CWSU, RFC, AWC, SPC, WPC
FAA: Tower, AFSS
Other: EM, Red Cross
Input Sources3D Reflectivity Cube
Spatial Resolution: 0.01o Latitude (~1.11 km) x 0.01o Longitude (~1.01 km at 25oN and 0.73 km at 49oN)
Temporal Resolution: 2 minutes
As a result of the radar horizon and terrain blockage, each radar can only sense down to a certain altitude above Earth’s surface. The RALA product uses the lowest altitude from all of the available radars at each horizontal grid point. This ensures that the reflectivity at the lowest altitude is depicted.
At each horizontal 2D grid point, the reflectivity value is checked in the vertical grid from the bottom up. Once an “available” data value is found, that reflectivity value is assigned to the RALA value for that horizontal grid point. Data below radar beam heights or blocked by terrain are considered “unavailable”.