Shows radar echoes in any of several formats. Reflectivity is simply a measure of power returned to the radar in decibels (dBZ).
0.5 deg. Shows reflectivity from scan elevation 1, tilted 0.5 deg from the ground. This is exactly the same as "base reflectivity" shown in the radar main menu, so you should not have to select this item.
1.5 deg. Shows reflectivity from scan elevation 2, tilted 1.5 deg from the ground.
2.4 deg. Shows reflectivity from scan elevation 3, tilted 2.4 deg from the ground.
3.4 deg. Shows reflectivity from scan elevation 4, tilted 3.4 deg from the ground.
Extended (248 nm) 0.5 deg. This is similar to the 0.5 deg reflectivity scan, but shows it over a wider area (248 nm). This comes at the cost of degraded resolution (1.1 nm instead of 0.54 nm).
Composite. Composite reflectivity blends all available elevations, showing the highest reflectivity in all elevations above a given point on Earth. This is useful for showing all echoes returned by the radar, regardless of scan elevation. However this masks important features useful for severe weather forecasting, such as hook echoes and reflectivity gradients which are seen only on base slices. Composite reflectivity can give false impressions of precipitation at the surface from suspended precipitation, as in storm anvils.
Extended (248 nm) composite. This is similar to the composite product but reaches over a wider area: 248 nm instead of 124 nm.